Friday, February 22, 2008

2. Manual Transaxle
2.1 General
M5/6GF2 The manual transaxle installed on the NF has been developed newly to get a better shift feeling, durability. Some problems that occurred on the current transaxle such as gear jump out, noise and early worn out or broken parts may be settled designing and adopting new concept, structure. To produce commonly for both five speed (M5GF2) and six speed manual transaxle (M6GF2), the structure of transaxle cases are same each other. Also the clutch control system had been drastically enhanced for the reliability and durability, new concept and device has been applied.
5th / 6th
Max. Gear
SAE 75W/85
Clutch size (mm)
Distance between shaft (mm)
Overall length (mm)
Max. Torque (kgfㆍm)
Vehicle affected
Three shafts
Two shaft
Shaft layout
Triple: 1,2,3 / Double: 4,R
Triple: 1, 2
Shift fork
Shift rail
55.8 / 56.4
Weight (Dry, kg)
SAE75W/85 (1.9ℓ)
SAE75W/90 (2.1ℓ)

1) Shaft layout: Three-shaft structure has been adopted, two for output shafts and one for input shaft. Three-axis type has a merit,
- Possible to reduce the transaxle overall length (Easier to install on the vehicle and as the shaft is long, the shaft deflection may occur).
- Higher capacity of torque with lower noise and better durability.
- Modern design concept in worldwide manufacturers.
- Possible to use or produce commonly the transaxle case and all parts for five speed and six speed transaxle without changing the structure and re-design (6th speed transaxle can be produced just by adding 6th speed gear in the 5th speed transaxle).
EF: M5GF1 (2-axis type with one output shaft)
NF: M5/6GF2 (3-axis type with two output shafts)
Due to the double output shafts on the M5/6GF2, the final gear ratio (F.G.R) can be classified into two ones; FGR #1 and FGR #2. You may confuse the rotating direction of wheel (differential gear) will be opposite to the input shaft but this 3-axis type is a quite different concept comparing with the old 3-axis type FF (front engine, front driving) transaxle. Two output shafts are charge of different gear (speed) for power transmission.
2) Clutch system:
CSC (Concentric Slave Cylinder) system has been applied on the NF.
EF: M5GF1 (Conventional CRC system with push type dry single plate with diaphragm spring)
CSC assembly
CRC, release bearing and fork
NF: M5/6GF2 (New CSC system with push type SAC) --> SAC: Self Adjusting Clutch
Quick connector
The clutch release bearing and fork were removed to enhance the efficiency for clutch control system. CSC system can make possible to reduce the number of consisting parts.
- NF2.4L, D2.0VGT
- JM D2.0VGT
- CM δ-2.7L
- CSC Operation
As depress the clutch pedal, the hydraulic pressure is applied with the direction of the arrow as shown in the picture and then CSC (release bearing & release cylinder portion) will push the diaphragm on the clutch cover. Removing a clutch release control parts including of release bearing and release cylinder from the manual
transaxle vehicle, it built in a module to reduce the parts weight, usage and improve the operating efficiency. The overall system efficiency may increase by 5∼10% comparing with the conventional release bearing and fork type. The total number of system component may decrease from fifteen to one and the weight reduces about 0.8kg comparing the current M5GF1 model.
Additionally applying the quick connector, the labor time for assembly or repairing also will decrease.
Quick connector
Air bleeding port
· 유럽/북미에서 확대 적용중
- FORD, GM, OPEL, Benz, Audi, FIAT, Renault, L/Rover,
Peugeot, Saab, Volvo, Daewoo, Nissan, Ssangyong등
3) Section view (M5/6GF2)
6th speed gear (M6GF2)
1st speed gear
2nd speed gear
Reverse gear
5th speed gear
3rd speed gear
4th speed gear
Input shaft
Output shaft #1
Output shaft #2
2.3 Specification
2.0 I4
2.7 V6
Gear ratio








For 1st /2nd /R
For 3rd /4th /5th /6th

- F.G.R #1 and F.G.R #2
Due to the double output shafts on the M5/6GF2, the final gear ratio (F.G.R) can be classified into two ones; FGR #1 and FGR #2.

Output shaft#1 (0.05T~0.10T)
Output shaft#2 (0.05T~0.10T)
Input shaft (0~0.05T)
2nd speed gear
Differential (0.15T~0.20T)
2.4 Comparison
2.4.1 Three-shaft transaxles
Model: M5/6GF2
- Application: NF
- Max. Torque: 31kgf.m
- Length: 379.6mm
- Clutch control: C.S.C (Concentric Slave)
Model: MQ350
- Application: Golf, Bora, Transporter
- Max. Torque: 27.5kgf.m
- Length: 364mm
- Clutch control: C.S.C (Concentric Slave)
& Kia
Model: GQ35-6
- Application: Under developing
- Max. Torque: 35kgf.m
- Length: 344.5mm
- Clutch control: TBD
Model: PK5, 6
- Application: Safrane, Laguna, Espace,Master, Clio
- Max. Torque: 27kgf.m
- Length: 375mm
- Clutch control: C.S.C (Concentric Slave)
2.4.2 Comparison with the current models
NF M5/6GF2
Two shafts
Three shafts
Output shaft for 1st/2nd/R
Output shaft for 3rd/4th/5th/6th

2.5 Components
2.5.1 Control module assembly
Shift lever
Control lever
Control module
To prevent the gear jump-out problem and smoother shift feeling, the newly designed control module has been applied as shown on the picture. Also lower shift effort and the enhanced durability have been considered.
.5.2 Shift rail & fork
Two shift rails are used to move four shift forks as shown on the picture. No additional shift rail is added for six-speed transaxle mechanism.
1st-2nd fork
Reverse fork
3rd-4th fork
5th-6th fork
2.5.3 Synchronizer
The purpose of these systems is to improve the shift quality, especially for the 1st and 2nd gear shifting that most drivers feel the shift shock. In addition to the more enhanced shift feeling while driving, the shift effort, 2nd resistance feeling can be reduced and the durability also will be improved. It prevents malfunctioned shifting due to overheat or burning.
Three friction faces
4th, R: Double cone synchronizer
1st, 2nd, 3rd: Triple cone synchronizer
Two friction faces
Key spring & ballThe synchronizer key gives the secure engagement or disengagement of synchronizer sleeve when the shift rail is moved. The ‘key with ball and coil spring’ had been most widely adopted in the passenger vehicles and the NF has also same type.
.5.4 Poppet ball with linear bearing
Poppet ball
The main purpose of the poppet ball is to prevent the gear from jump out and it provides the shifting with stable detent feeling.
No bearing
→ Rough shift feeling
Rolling bearing
→ Medium level shift feeling
Rolling/Sliding bearing
→ Best shift feeling
X-3, RD, MX
VW Golf, Audi A6, Benz A190, Toyoda Camry
M5/6GF2(NF, CM)
2.5.5 Transaxle lubricant
The newly developed oil is applied on the M5/6GF2 model; the viscosity of new oil is lower than current one. The low viscosity oil is for,
- Improving the shift quality at low speed gear.
☞ The balking feeling can be removed and the shifting effort will be reduced while N→1st gear, N→R shifting under the cold condition.
- 40℃
- 20℃
API grade
SAE grade
Synthesized oil
Mineral Synthesize oil
Main ingredient
New oil (NF)
Current oil (EF)*
*; Not only the oil for M5/6GF2 but also the oil for M5GF1 (EF, FO…), Alpha/Beta and FR M/T will adopt the newly developed low viscosity permanent use oil from August, ‘04MY.
Quantity (L)
HP, H-1, SR
SAE 75W/90
SAE 75W/85







2.6 CSC (Concentric Slave Cylinder) clutch system
2.6.1 Layout
Pressure Pipe
Concentric Slave Cylinder
Master Cylinder
Brake-Fluid Reservoir
Quick Connector
The pipe shape shown on this figure is just to explain the layout, different from the actual one.
2.6.2 Installation
CSC tightening torque (Three positions)
1.2~1.5 Kgf.m
Front view
Side view
Connected to pressure pipe
For air bleeding
2.6.3 Pipe disconnection
Correctly assembled
Remove the clip on the groove using proper tool.
Pull out the pipe after removing the clip and the removed clip can be reused.
2.6.4 Pipe connection
‘Click’ sounds: Correct connection
Insert a clip to the groove
Push the pipe to the arrow direction
Wrong way:
Make caution the direction
Correct way
2.6.5 Air bleeding
Air bleeder
Air bleeder cap
Plug: Tightening torque: 2.5∼2.9kgf.m
Fix the air bleeder body
- Procedure:
1) Open the air bleeder cap and connect the vinyl hose.
2) Loosen the plug and do pumping the clutch pedal 15 times or more.
3) While depressing the clutch pedal, tighten the plug. Pump the clutch pedal about 5 times and loosen the plug again.
4) Repeat the above procedure ‘3)’ until the air bubble disappears.
2.6.6 Cautions for handling
- When install the engine & transaxle assembly on the vehicle:
Before assemble the transaxle with the engine, connect the vinyl hose at the pressure pipe for CSC as shown in the figure. Because the remained oil inside of CSC may be injected due to the depressed diaphragm of CSC while docking the engine with transaxle.
Vinyl hose to prevent the contamination caused by the injected oil from CSC
- While handling the CSC module:
Do not grasp the pipe or don’t apply too strong load on the CSC pipe as shown in the figure. It may cause the deflection of pipe.
- Seal ring inspection:
While overhauling to repair the engine or transaxle, be careful not to make damage in the O-ring indicated on the figure. It may cause the oil-leaking problem.
2.7 SAC (Self Adjusting Clutch)
Clutch cover (SAC) Generally as the mileage increases on the manual transaxle vehicle, the disc facing may wear out and the cover load will be higher. This will cause the higher effort force for clutch pedal. To prevent this demerit of the conventional clutch system, the self-adjusting clutch system has been developed. Adopting SAC, the clutch pedal depressing effort may increase as the vehicle mileage increases but it is possible to minimize the rising amount of effort force and also the clutch replacement period can reduce.
- Application: NF 2.4L, D2.0VGT, HP, SM (VGT)
Diaphragm Spring
Coil spring
Sensor Spring
Diaphragm Spring
Adjusting ring
Conventional Clutch cover Assembly
SAC cover Assembly
· Proportioning to the amount of worn out disc facing, the clamping load may increase as the position of diaphragm spring moves toward transaxle side in the conventional clutch system.
· In spite of worn out disc facing, the diaphragm spring will not move toward transaxle side because the adjusting ring also moves.- Structure:
- Assembly direction:
S.A.C Cover Assembly
Conventional Cover Assembly
The face marked with ‘T/M side’ as shown on the figure must face toward the transaxle direction when assemble the clutch disc. Otherwise, there may be an interference with the engine. This marking (‘T/M side’) is applied not only on the NF but also other models adopt the clutch system of ‘LUK’ (KD part).
In case of S.A.C system, the cover is automatically adjusted depending on the amount of worn-out disc, so when replace the clutch cover; the disc also must be replaced together. That is, to improve the quality and minimize the declination, the cover and disc are supplied as a set. If only the disc is replaced, a slip may occur caused by the decreased initial clamping load due to the abnormal operation of adjusting ring. Also it will result the difficulty in torque isolation caused by the shorten release travel due to the excessive thickness for the disc. Therefore, it is highly recommended to replace a set of disc and cover in case of the clutch system adopts the self-adjusting mechanism.

2.5 ~ 3.6 Kgf.m
M8 X 6pcs.
NF 2.0/2.0LPI
Cover Ass’Y
M6 X 9pcs.
Mounting Bolts
1.2 ~ 1.5 Kgf.m
Cover Ass’Y
Tightening torque for bolt


(2.4L )
1. Introduction
1.1 Specification of theta engine
1.2 Overview
2. Engine Mechanical
2.1 Aluminum Cylinder Block
2.2 Timing Chain System
2.3 BSM(Balance Shaft Module)
2.4 Intake Manifold
2.5 Exhaust Manifold
2.6 Cylinder Head
2.7 Tightening Method
2.8 Camshaft
2.9 Valve Train System
2.10 Driving Belt System
2.11 Ignition System
2.12 Cooling System
2.13 Fuel System
3. CVVT System
3.1 General for CVVT System
3.2 Components
3.3 Operation Mechanism of CVVT System
3.4 Cautions at CVVT maintenance
3.5 CVVT failure Code (DTC)
4. ETC(Electronic Throttle Control)
4.1 Throttle Motor
4.2 Accelerator Position Sensor
4.3 Throttle Position Sensor
4.4 Initializing Method of Throttle Body for ETC
5. EMS (Engine Management System)
5.1 Relay(Engine Control relay, Fuel pump relay)
5.2 Injector
5.3 Purge Control Solenoid Valve
5.4 A/F Ratio Compensation

1. Introduction

The theta(Θ) engine newly installed on the NF-vehicle is the 2.4 DOHC MPI engine developed by HMC.
The theta(Θ) engine consists of aluminum block so that it is lighter about 45% than the engine made of iron cast. Further, the intake manifold is made of plastic so that the resistance of airflow and its weight are reduced, as a result, the fuel efficiency could be enhanced.
The theta (Θ) engine is installed with a silent timing chain to enhance the endurance. The valve train system is adopted with MLA (Mechanical Lash Adjuster) to enhance the fuel efficiency.
In the cooling system, the PWM type is adopted for controlling the cooling fan so that the cooling effect is enhanced due to more precise control. In addition, the capacitance of the water jacket is minimized to reduce the warm up time period.
The CVVT device, the intake valve variable timing system, is basically installed at the theta (Θ) 2.4 engine so that the fuel efficiency and the torque at low and middle speed are enhanced.
As the BSM (Balance Shaft Module) is installed at the theta (Θ) 2.4 engine, the noise and vibration are remarkably reduced. The theta engine is designed for embedding an oil pump inside of the BSM. In addition, the engagement strength between the engine and the transmission is enhanced due to the ladder frame.
As the ETC (Electronic Throttle Control) is installed at the theta (Θ) 2.4 engine, the idling speed control, throttle valve opening control, TCS control and driving in continuous speed are performed by one throttle valve so that the system is simplified and the failure rate is reduced.
For the NF vehicle, the engine ECM is installed in the engine room for easiness of maintenance. The ECM comprises of high performance 32bit micro-processor to perform the control exactly and
fast. Furthermore, the ECM and the TCU is unified in one PCM.
1.1 Specification of Theta engine
In-line 4 cylinders
Capacity (cc)
Type of Combustion chamber
Bore(mm) × Stroke(mm)
Compression Ratio
Torque Max. (kgf.m/rpm)
Output Max. (ps/rpm)
Idling Speed (rpm)
Adjusting valve gap
MLA (Shimless)
Fuel Pressure (kg/cm2 )
Fuel Device
Capacitance of Fuel Tank (Liter)
Fuel Rail
EV6 Long
Fuel cut (Over Run)
Ignition Order
Ignition Timing (Idling)
Ignition Device
DLI (cigar type ignition coil)
Spark plug
Knock Control
Adopted (non-resonance type)
Exhaust System
Air Flow Sensor
Hot Film Type
Variable Intake Valve Timing System
Exhaust Valve Opening (BBDC)
Exhaust Valve Closing (ATDC)
Catalytic Device
Oxygen Sensor
Capacitance of Engine Oil (Liter)
Oil Pump Type
Oil Filter Type
Control Method / Thermostat type
Inlet Control / Wax. Pellet
Capacitance of Cooling Water (L)
2.35 L
Opening / Max. opening temperature
82˚C / 95˚C
1.2 Overview
Front View
Crankshaft pulley
Water pump pulley
A/C Compressor
Power steering pump
Driving Belt
(One Belt)
Oil filter
Rear View

Top View
ECT Sensor
Oil level gauge
Exhaust manifold

Bird-eye View
Fuel rail
Ignition coil

Side View (Right)
Water pump
Oil fan
Ladder frame

Side View (Left)

Start motor
A/C Compressor
Power steering Pump

2. Engine Mechanical

2.1. Aluminum Cylinder Block
- 45% lighter than iron casting cylinder
- Changing in cylinder block water jacket shape and reinforcing the rib
- Enhanced cylinder block and transmission jointing strength

By changing the cylinder block material into aluminum, the cylinder block can be lightened up to about 45% less than iron cast block so that the fuel efficiency is enhanced. As shown in bellowed figure, the structure of the water jacket is designed to link each cylinder so that the cylinders are enveloped by water jacket. As a result, the capacitance of the water jacket is minimized to reduce the warm up timing.
In addition, ladder type frame is employed to enhance the joining strength between engine and transmission so that the noise and vibration are reduced.

OCV Filter
Water jacket
Added lib

2.2 Timing Chain System
- By employing low noise chain, the chain meshing noise and crashing noise are reduced
- Reinforcing timing chain cover strength and enhancing the sounds
- The endurance is enhanced by changing the timing chain
- By employing variable valve timing system, the torque for low or middle speed is optimized and fuel efficiency is enhanced.
Timing Chain

Tensioner Arm
Mechanical tensioner
Oil pump Chain
Oil pump
Ex. Camshaft Sprocket
Chain guide

2.2.1. Installing method for timing chain and auto tensioner
1) Dispose the crank axis sprocket half-circle key to the horizontal line of the cylinder block assembling surface to align with 1st cylinder top dead center.
2) Meet the TDC mark of the intake·exhaust cam shaft sprocket to the upper surface of the cylinder head.
(There are two marks on the camshaft sprocket surface. Between them, align to the ‘━’ TDC mark. Note: ‘●’ : Timing Chain Mark)
3) Turn the timing chain to meet the crank axis sprocket timing mark (‘●’) to the middle position of the colored link of the chain.
4) Meet the intake·exhaust cam shaft sprocket timing mark (‘●’) to the middle position of the colored link of the chain.
5) Install the timing chain guide (A).
6) Install the timing chain guide (B).
7) Install the auto tensioner after fixing it with a fixing pin by pushing the rod of the auto tensioner thoroughly.
8) After the fixing pin is removed, check the timing chain whether it is properly installed or not.
9) After turn the crank axis shaft with two rotations, check the timing chain mark.
- When the timing chain is installed, do not apply excess force (to prevent the timing chain link being distorted)
Timing Mark
Timing Chain Mark
< 밸런스 샤프트 모듈 >
Timing Mark

2.3. BSM (Balance Shaft Module)
- Reducing engine noise and vibration
- Embedding oil pump in balance shaft
- Driving type using timing chain

The balance shaft is installed at the lower portion of the oil pan to reduce the noise and vibration of the engine. In the balance shaft module, an oil pump supplying oil to engine is installed.

2.3.1 Components
Tightening Torque
Crankshaft sprocket
Oil pump, BSM
Chain oil jet
Flange bolt
2.7 ~ 3.1 kg.m
2.3.2 Installing method
Crankshaft key
Flange Bolt 3EA
Bearing cap

(1) Using flange bolt, the balance shaft module (BSM) is installed as shown in figure.
(2) After installing the crank shaft key, turn the crank shaft to set to the horizontal line on the
bearing cap block installing surface.
(3) Align the timing of the balance shaft module at the state that the sprocket of the crankshaft is installed.
(4) Install the balance shaft at the state that the chain for driving of balance shaft module is aligned to the timing mark appropriately.
(5) Set the timing mark of the crank shaft sprocket and oil pump sprocket to the chain link according to the color of the chain.
(6) After linking the chain on the balance shaft module, fix it using balance shaft fixing bolt.

Crankshaft Timing Mark for BSM
BSM Timing Mark

2.3.3 Structure of BSM and Operation Principle of SPOOL VALVE

1st balance shaft
Spool valve
1st Oil pump
2nd oil pump
2nd balance shaft

The structure of BSM, as shown in below figure, comprises three axes, a pair of gear, two oil pump, a spool valve and oil circuit. For compensating the second vibration from the engine, the first and the second driver axes are installed with the same size. The oil pump is installed at the input axis and the second driver axis, respectively. The first oil pump (Full Time) is driven with 1.25 times of the engine rpm and the second oil pump (Part Time) is driven with 2 times. The second oil pump also perform an additional function to reduce the rattle noise occurred between the driver axes. The spool valve is operated by the oil pressure of main gallery. At the high pressure, the power loss by the oil pump is high so that the power loss would be reduced by adjusting the oil pumping performance of the second oil pump using the oil pressure circuit.

2.3.4. Function of Oil Pump
- Pbf : Oil pressure before passing the oil filter
- Pst : Oil pressure when the spool valve is set on the Start Transition position
- Pbt : Oil pressure when the spool valve is set on the Bypass Threshold position

(1) Pbf < Pst : All of the first oil pump and the second oil pump supply oil to the engine. High temperature and low speed
(2) Pst < Pbf < Pbt : The first oil pump steadily supplies oil to the engine with 100% performance while the second pump gradually reduces the oil supply
(3) Pbf > Pbt : The second oil pump do not supply oil to the engine and some of the oil supplied from the first oil pump would be bypass.

Pbf = Pst
Pbf < Pst

Pbf = Pbt
Pst < Pbf < Pbt

Pbf > Pbt

Here, the position of the spool valve is determined by the oil pressure. The oil supplying performance is adjusted according to the spool valve position. The operation of the spool valve is very important because the oil pressure is closely related with the oil supplying performance.

High Oil Pressure → Shift of Spool valve to right → Reducing in Oil supply → Lowered Oil Pressure → Shift of Spool valve to left → Recovering Oil supply → High Oil Pressure → Repeat

2.3.5 Path of the Engine Oil Supply


CVVT Assembly
Oil filter

2.4. Intake Manifold
- Length/Cross-sectional shape are optimized for enhancing torque at all rpm zone.
- As the material is changed (aluminum ⇒ plastic), the air flowing resistance is enhanced so the output and torque is increased

The intake manifold is a pipe system for leading the air into the cylinder with reducing the resistance of air flow.
The intake manifold applied to the Theta engine by being made of plastic material has lower resistance in air flow than the manifold made of aluminum so that the intake efficiency is enhanced and the total weight of engine is being lightened to get enhanced fuel efficiency.

2.4.1 Installing method


(1) At first, assemble the gasket of manifold to the cylinder head.
(2) After install the intake manifold ASSY, Put on the flange nut and bolt washer ASSY in accordance with the order of ①, ②, ③, ④, ⑤ and then tighten with nominal torque.
(3) Assemble the stay of intake manifold in the order of ⑥, ⑦ with nominal torque.

2.5. Exhaust Manifold
- Length / Cross-sectional shape are optimized for enhancing torque at all rpm zone.
- As the material is changed (iron cast ⇒ stainless steel), heat resistance is enhanced.
This is device for gathering and exhausting the combusted gas in the cylinder through the exhaust pipe. Generally, this is made of cast iron. However, for theta engine, the exhaust manifold is made of stainless and optimized in the length and cross-sectional area. As a result, the heat resistance is enhanced.

2.5.1 Installing method
Exhaust manifold
Nut lock

(1) Assemble the gasket of the exhaust manifold to the cylinder head.
(2) After install the exhaust manifold ASSY to the cylinder head, tighten the flange nut in the order of ①, ②, ③, ④, ⑤, ⑥, ⑦ with nominal torque.
(3) Using flange bolt, assemble the exhaust manifold stay with nominal torque.
(4) Assemble the exhaust manifold heat protector with nominal torque.

2.6. Cylinder Head
2.6.1 Components
Bolt-ASSY Cylinder Head

Washer-Cylinder Head

Bolt-Cylinder Head

2.6.2 Tightening method of cylinder head bolt
① Method for this operation is the guide line when the engine is left after it is stopped (at 20˚C of cooling water temperature)

Ⅰ② Order for bolt joining
※ when the bolt is joined manually
1 step
2 step
3 step
Tightening torque and angle
+ 90˚
+ 90˚

2.7 Tightening Method
The method for tightening bolt is the torque method in general. Even the torque is precisely maintained, the tightening force may be changed because of the variation of frictional force (axial load) between the bolt seat face and screw face. Therefore, the axial load is not set highly. However, if the bolt is tightened by angular method (elastic angular method or plastic angular method), then the variation of axial force can be minimized, so that the tightening force can be high and the variation of axial force can be reduced.

2.7.1 Plastic torque method and Plastic angular method
(1) Plastic torque method: The torque method in which the jointing force at some portion (screwed portion not jointed, shank portion) of the joining body (bolt) is larger than the break down strength.
(2) Plastic angular method: The joining method with initial tightening torque and joining angle.
[Note] When the plastic-range joining is performed by torque method, the plastic variation amount
of the bolt is not managed precisely. Therefore, it is possible to perform the plastic-range
joining using torque method.
2.7.2 Comparing the torque method, the elastic angular method, the plastic angular method
(1) Tightening force:
The initial tightening force is high in the order of torque method < elastic angular method < plastic angular method.
(2) Variations of initial tightening force
The variation of the initial tightening force is lowered in the order of torque method > elastic angular method > plastic angular method.

2.7.3 Defects of the plastic tightening method
(1) When the plastic tightening method is used, the cross-sectional area of the bolt would be reduced. Therefore, the re-usable times would be decreased.
(2) If there is any fault in joining operation, the bolt would be distorted heavily. Therefore, the bolt could be damaged easily.
※ As the bolt jointed with the plastic angular method has limited re-usable times, it is prefer to replace it not to use again as possible.
Joining step
1 step
2 step
3 step
Joining condition
Joining method
Join 2.5kg.m with
torque method
Join in 60˚ with
angular method
Join in 60˚ with angular method
2.7.4 Cautions for applying angular method (elastic, plastic)
(1) It must observe that the engine oil be coated or not
(2) The removed bolt, nut and washer should be disused.
(3) The plastic tightening method condition should not be used by converting into the torque method. If doing so, the bolt may be enlarged or damaged so that the bolt could be broken during tightening the bolt or driving the vehicle.
(4) When angular method is used, do not turn additionally the bolt to confirm the final joining torque. If doing so, the bolt may be enlarged or damaged so that the bolt could be broken during tightening the bolt or driving the vehicle.
(5) When plastic angular method is used, if it feels that the bolt may be enlarged (the bolt or nut may be turn without increasing torque) at just before completing the joining, then the joining operation condition should be checked again.
(6) When elastic angular method is used, the bolt can be used again. If the initial tightening torque or angle is not improperly set, then the bolt or nut should be released and then the joining operation should be performed again. However, when the plastic-range bolt is used, the possibility of re-usability should be checked before it is re-used (at maintenance, it is proper to replace it

2.8 Camshaft
2.8.1 Components
Tightening torque
Intake camshaft
Exhaust camshaft
CVVT assembly
Exhaust cam sprocket
CVVT bolt
5.5 ~ 6.5 kg.m
Exhaust cam sprocket bolt
5.5 ~ 6.5 kg.m
2.8.2 Assembly method of CVVT and camshaft
(1) Install the CVVT(component 3) to the Dwell pin at intake cam shaft (component 1). Please caution that it should not be installed at the hole of oil supplying.
(2) The CVVT should not be rotated in the state that the CVVT is assembled to the Dwell pin of the intake camshaft.
(3) Install the intake camshaft having CVVT using bolt (component 5) according to the joining torque specified in above table. When the CVVT is assembled to camshaft, the camshaft should be fixed and the housing and sprocket are not limited.
(4) Install the exhaust cam sprocket (component 4) to dwell pin of exhaust camshaft (component 2).
(5) Install the exhaust camshaft having sprocket using bolt (component 6) according to the joining torque specified in above table.
2.9 Valve Train System
The valve lift used in the direct driven OHC engine is mainly classified into the hydraulic valve driving device (HLA) and the mechanical valve driving device (MLA).

(1) Valve gap adjusting device employed in new NF model
For theta engine, using the MLA mechanical valve gap adjusting device, the valve timing, the initial valve gap and cam design appropriate to the MLA characteristics can be performed. Therefore, fuel efficiency is enhanced and MLA without core can be employed.

(2) Initial valve gap measuring and tappet setting method
① Initial valve gap value
At cooling engine (20˚C)
At heating engine (80˚C)
② Measuring method for valve gap
ⓐ After the cylinder head is installed at the cylinder block, measure at the state that the cylinder head bolt is jointed by nominal torque.
ⓑ Install master tappet (thickness: 3.0±0.01mm) at each cylinder.
ⓒ After installing the cam shaft, join the cam cap bolt with nominal torque.
Note) when the cam cap is installed, to prevent the valve and piston from being interfered, the position of key slot of the crankshaft sprocket should be directed upward.
ⓓ Turn the timing mark of the sprocket of the intake·exhaust cam shaft to be aligned with the upper surface of the cylinder head so that the 1st cylinder is positioned at the compression top dead center. (at that time, measurable valve is intake of NO.1, NO.2 combustion chambers and exhaust of NO.1, NO.3 combustion chambers)
ⓔ Using THICKNESS GAGE, measure the gap (I,E) between the cam base circle and center core. (at that time, scale of THICKNESS GAG should be less than 0.01mm)
ⓕ Turn the intake·exhaust cam shaft to 180 degree along to the positive direction (clockwise direction) to meet the 4th cylinder with the compression top dead center. (at that time, the measurable valve is intake of the NO.3, NO.4 combustion chambers and exhaust of the NO2, NO.4 combustion chamber)
ⓖ Using THICKNESS GAGE, measure the gap (I,E) between the cam base circle and center core.
ⓘ According to following equation, select tappet thickness.
- Core thickness at intake side (mm) = (I-0.20) + 3.00
- Core thickness at exhaust side (mm) = (E-0.30) + 3.00

③ Guide line for installing the mechanical tappet
ⓐ Disassemble the cam shaft and remove the mast tappet from each cylinder.
ⓑ After coat the engine oil outside of the tappet, insert the tappet softly.
ⓒ Re-install the cam shaft and then join the cam cap bolt with nominal torque.
ⓓ Check the valve gap again.

2.10 Driving Belt System
- By driving all auxiliary machineries using one serpentine belt, the alignment of the auxiliary
machinery is optimized and the vibration by rotating is reduced so that vibrating amplitude is reduced.
- As auto tensioner is employed, the belt endurance is enhanced.

Crank-shaft pulley
Water pump pulley
A/C Compressor
Power steering pump
Driving Belt
(One Belt)

2.11 Ignition System
2.11.1 Specification
Ignition Coil
Theta engine (2.0/ 2.4)
Stick Coil (Cigar Type)
Operating Voltage
5~ 16V
Operating Temperature
-30 ~ 130˚C
1st Coil Resistance
Spark Plug

2.11.2 General Information
The ignition timing is controlled by the electrically controlled ignition timing system. The ignition timing data in accordance with the engine operating condition is controlled by program stored in the memory of ECM.
When the sensor signal detected by each sensor and the signal for intermitting the first current using ignition data are supplied to the power transistor, the ignition coil is effective and the ignition timing is controlled with optimized timing.

2.11.3 Ignition Coil
The ignition coil is sparked by the engine ECM in accordance with the spark order so that the power TR embedded into engine ECM controls the ignition coil. Due to the diagonal winding, the ignition coil can be minimized in size and lighted in weight.

2.12 Cooling System
2.12.1 Generals and Main specification
The cooling system is a device for cooling the heated engine to protect the engine from being damaged and to maintain the engine with a proper temperature. The combustion temperature in the cylinder can be increased up to 2000~2500˚C so that the high temperature is transmitted to the cylinder wall, cylinder head, piston, valve and so on. Therefore, the strength could be degraded and the engine could be reduced in endurance. Further the combustion condition may be degraded so that knocking or misfire can be occurred and the output can be lowered. On the contrary, if the temperature is too lowered then the engine efficiency may be degraded because the wasted heat capacity is increased and the fuel consumption could be increased. Accordingly, the engine temperature should be maintained about 80 ~ 90˚C.

Coolant Flow Diagram

Cylinder Head
Cylinder Block
Water Pump
Thermo Stat

Cooling controlling method
Cooling circulation type
Entrance control method

Cooling method
Forced circulation using electric fan

Cooling fan controlling method
PWM(Pulse Width Modulation) method

Capacitance of cooling system
2.35 litter

Wax pallet type including ziggle valve

Normal opening temperature

Maximum opening temperature

2.12.2 Main Specification
2.12.3 Structure and Control for Cooling fan
Structure of Cooling fan
Shroud(1) There is one cooling fan, the radiator fan
(2) Cooling fan speed control – PWM method
PWM Module Body installation

Location and module

Input and output
ECM Signal
Fan Motor

Input duty(%)
10, 30, 35, 40, 50, 60, 70, 80, 90
Approved Voltage (Output duty)
Duty 10% : 0V
Duty 30% : 4.1±0.065V
Duty 60% : 8.2±0.065V
Duty 70% : 9.57±0.065V
Duty 100% : Min. 12.5V
Soft start
10~14 sec.

Soft start
Relations between Input duty and Output duty
Input duty
Output duty
Input duty
Output duty

- When the cooling water temperature sensor is malfunction, the duty would be output in 100% so that the fan should be continuously operated.
- When the cooling water temperature is higher than 115˚C, the compressor should be OFF.(Cooling water temperature hysteresis 7˚C)
- The cooling water temperature hys.2˚C, vehicle speed hysteresis. 5km/h

※ Hysteresis(hys): Section in which the cooling system could opera

Cooling fan Controlling table
A/C input
Vehicle speed
Coolant temperature (℃)
A/C input

Middle1 ≤
A/C input <
Middle 2
Middle 2 ≤
A/C input

※ Middle 1 : 12.0 kgf/㎠
Middle 2 : 15.5 kgf/㎠ ( 1.0 kgf/㎠ = 14.22 psi)

2.13 Fuel System
The fuel system of NF vehicle is RLFS type in which the return line of fuel is completed in the fuel tank. It is similar with the conventional type but it is properly designed for the characteristics of the NF vehicle.
2.13.1 Characteristics of the RLFS (Returnless Fuel System)
As the surplus fuel supplied to engine is returned by the pump module in the fuel tank, the fuel line returning from the engine to the fuel tank is removed. Accordingly, vaporized gas and vapor lock due to the temperature difference between fuel tank and delivery pipe are reduced and the fuel temperature in the engine room is maintained in room temperature so that the volume efficiency could be enhanced.

2.13.2 Order of Fuel Supply

Fuel Tank→Fuel Pump→Fuel Filter→
Return Line
Fuel Pressure regulator
→Fuel Pipe→Injector


Delivery pipe
Fuel pump
Fuel pressure regulator
Fuel filter
Fuel tank

2.12.3 Specification and diagram of Fuel System
Filler Neck
Fuel Tank
Tube Assembly
2.12.4 Characteristics of Fuel System
(1). Fuel Tank
- Capacitance : 70 Litter
- Material : STEEL(Unleaded steel plate)
(2) Filler Pipe
- Material : STEEL
(3) Canister
- Mounting on the tank
- Active Carbon Material : WESTVACO-1100
- Active Carbon WORKING CAPA : 61g (Figure (Certificated)SPEC : more than 61g)
- Capacitance : 1200cc
- Common in Domestic and Europe
(4). Fuel Pump
- FLFS System is employed
- Fuel Pressure 3.5kgf/㎠
(5) Injector
- Type : EV6 Long
- Capacity : 187g/min
- Injection angle : 15˚ (cone angle : 8˚)
(6) Line for Fuel and Vaporized Gas
- Nylon tube or low permeability material is employed
- Outer Diameter of Fuel Line : 8mm
- Vaporized Gas Line : 6.35mm
(7) Cautions
- When quick connector is assembled, be careful for seal (O-ring)
- When quick connector is assembled, DOUBLE LOCK should be filled.
- It is ensure that the clamp of the assembly should be coupled.
(8) Checking Table for Fuel Sender
Float position
Sender Resistance (Ω)
Float gauge angle (˚)
Height of oil surface from the bottom of tank (㎜)
Tolerance of residual of fuel amount (L) : ±1L

3 CVVT System

3.1 Generals for CVVT system
The CVVT, the Continuously Variable Valve Timing, is the system by which the opening and closing timing of the intake valve is continuously changed by the phase variation according to the engine rpm and load of the vehicle, i.e., the system for varying the amount of the valve overlap. The purposes of the CVVT system are to comply with the strengthen the exhaust gas regulations as followings.
- Emission reducing
- Fuel efficiency enhancing
- Performance enhancing
- Idling stabilizing
Valve overlap
45 CA
Crank angle

The rotational movement of the crankshaft is transmitted to the intake cam shaft having the CVVT assembly via the timing chain installed at the front of the engine so that the intake cam shaft is directly controlled by the CVVT assembly.

3.1.1 Generals for Valve Timing
The opening angle of the intake valve of CVVT engine is controlled by 45˚CA.

Intake Valve Timing
Exhaust Valve Timing
Theta engine
45 CA


[Note] Valve Overlap
This is the time when the intake valve and exhaust valve are all open at top dead center of
exhaust stroke.
If the exhaust valve is open after passing the exhaust TDC, the exhaust will be accelerated by the exhaust inertia effect. At that time, if the intake valve is open just before the exhaust TDC, the intake air will be sucked by the vacuum force of the exhausted gas so that the volume efficiency could be enhanced.
The Variable Valve Timing System controls the opening-closing timing of the intake valve by adjusting the intake valve opening-closing timing and overlap variation with point.

3.1.2 Intake valve timing of CVVT engine according to load of the engine
At low load
and idle
At high load
and high speed
At high load
and low speed
At middle
Intake Valve Timing
Stable combustion
Reduced fuel

※ Remarks ① - Improved perfectly combustion by increasing combustion chamber pressure (valve overlap 0˚)
- Prevent to back-flow of exhaust gas
- Stabilize the engine rpm by enhancing exhaust gas and protecting the backward flowing of the intake manifold
Remarks ② - Increase amount of intake air (Delayed Intake valve closing timing)
- By retarding the opening timing of intake valve, enhancing output due to enhanced charging efficiency of air using the inertia of air flow, However, at low speed, by the backward flowing of mixed air due to the upward movement of piston, torque would be decreased and rotational movement would not be stabilized.
Remarks ③ - Prevent to back-flow of A/F mixture gas (Advanced Intake valve opening timing.)
Remarks ④ - Reduce emission gas : NOx (internal EGR)
- Reduce pumping loss

3.1.3 Intake valve opening-closing timing and Performance / Fuel Efficiency / Emission Gas
(1) Relationship with Performance
Generally, enhancement of the engine performance is dependent on how many air amounts could be sucked into the combustion chamber. Further, the opening timing of the intake valve is closely related with the enhancement of the intake efficiency.
① Opening timing of intake valve
For the most engines, the intake valve is open before TDC because the intake air can be sucked by using exhausted force of the used gas, if the intake valve is open during the exhaust valve is open prior to the piston TDC. However, if it is open too fast, the intake air may be exhausted through the exhaust valve. Therefore, the optimized valve overlap should be found. In addition, at low speed, the intake air flowing speed is slow, so if the intake valve is open to fast, the air intake would be hindered by collision between the exhaust and intake gases. Therefore, limited is to increase the valve overlap timing.
② Closing timing of intake valve
Even if the piston is starting upward movement after passing the bottom dead center, the intake air is still sucked by the inertia force. As the pressing force is increased as the piston moves upward, to close the intake valve when the two forces are offset each other (when intake air is not injected no more) is the best method.
As the intake air inertia force is larger as the speed is higher, it is proper that the closing time of intake valve is retarded as possible.
③ Relationship with fuel efficiency
The sucking air force during piston is moving downward and the pushing air force during the piston is moving upward are all the pumping losses.
As the intake and exhaust could be enhanced by increasing valve overlap, the pumping loss could be reduced. Accordingly, the fuel consumption ratio per unit time /unit power (g/kw.h) will be reduced.
④ Relationship with exhaust gas
A. NOx: The NOx could be reduced by decreasing the combustion temperature using internal EGR according to the increasing of valve overlap.
B. HC: The HC could be reduced by combusting again the gas not completely combusted using internal EGR.
However, as the valve overlap is increased, the combustion may be unstable; as a result, the HC amount could be increased. By finding the optimized valve overlap under each driving condition, the HC amount can be reduced.

[Note] Engine Performance according to the CVVT
(1) Reducing exhaust gas : Retard (decreasing overlap) : enhancing combustion/ reducing HC
Advance(increasing overlap) : decreasing combustion temperature/ reducing NOx

(2) Enhancing fuel efficiency : Advance (control internal EGR) : reducing pumping loss

(3) Enhancing low speed torque and power : Advance : low·middle speed – enhancing volume
Retard : high speed – enhancing intake inertia

3.2 Components

CVVT Assembly

3.2.1 CVVT(Continuously Variable Valve Timing) Assembly
• Location : Front of Intake camshaft
• Type of CVVT : vane type
• Operation range : 45±2˚ Crank angle
• Operation Condition
① Oil Temperature range : -40 ~ +130˚C
② Oil Pressure range : 0 ~ 1000kPa
③ Engine speed range : 650 ~ 6000 rpm
• Stopper Pin Release Pressure
Minimum release
Fully release

Principle of operation
(1) CVVT is installed at the intake cam shaft as shown in above figure.

(2) Bushing vane of CVVT, rotor vane and intake cam shaft are jointed in one body.
(They are always rotaing togeter: assembly “A” )

(3) CVVT housing and sprocket are jointed in one body.
(They are always rotaing togeter: assembly “B” )

(4) According to the oil supplied to advance room/retard room, there are pahse difference between the assembly “A” and assembly “B”.

(5) As the sprocket is linked with intake cam shaft by the timing chain, a phase difference of cam will be made at contro sot that the openng-closing timing of intake valve can be controlled.

3.2.2 OCV(Oil Control Valve)
① Voltage : 12V
② Coil Resistance : 7.4±0.5Ω(at 20℃)
③ Control current : 100 ∼ 1000 mA
④ Insulation Resistance : over 50MΩ (at 500V)
⑤ Assembly air-tightness : Leakage test - Leakage should be less than 1.0㎤/min
(Apply air pressure 200 kPa)
Operation condition
① OIL Temperature Range : -40 ∼ +130℃
② OIL Pressure Range : 0 ∼ 1000 kPa
③ Voltage Range : 10 ∼ 16 V

(1) Function of OCV
As a core control component of CVVT, it changes the opening and closing timing using the variation of the path of flow supplied to CVVT according to the control of ECM.
(2) Operating Principle
A. As a permanent magnet is installed at the plunger of OCV, if the power is applied to the connector, a magnetic field is induced at the coil so that the plunger is pushed.
B. As the spool joined with the plunger is moved, a flow path is formed by changing of the relative position from the sleeve.
C. The oil supplied to OCV is flow into the advance room or retard room of the CVVT via the cam shaft through the oil path newly formed.
(3) Internal Component

3.2.3 OTS (Oil Temperature Sensor)
The operating oil of CVVT is the engine oil so that the density is changed according to the temperature of engine oil. To compensate the variables due to the temperature, OTS (Oil Temperature Sensor) is used.
After the temperature of the engine oil before entering into the OCV (Oil Control Valve) is measured and sent to ECM, ECM compensates the OCV driving according to this temperature.

3.2.4 OCV Filter
This is filtering the foreign material in the engine oil supplied into the OCV (Oil Control Valve).
It can be used permernantly so that it can be re-used after cleaning.

3.3 Operation Mechanism of CVVT System
3.3.1 Control Principle of CVVT
- The bellowed figure, the structure of CVVT, shows the relative motion of housing vaine to the rotor vane.

(1) Before cranking, if all of oil are removed, then the vane is in maximum retard state.
(2) After cranking, oil is supplied to advance room and retard room of CVVT.
If the pressure of oil flown into advance room is larger than the force of stopper pin, then the vane starts to move.
(3) If advance is needed according to the driving condition, then the spool of OCV moves according to the CPU signal and the oil flows into the advance room from the retard room, so that the vane is moving to the advace side.
(4) If retard is needed according to the driving condition, then oil flows into the retard room from the advance room so that the vane is moving to the retard room.
(5) If it is needed that certain angle should be maintained, the certain angle could be held by supplementing the leaked oil amount. At that time, the advance oil path is slowly open, at last, the retard room is closed.
However, the position is slightly different according to the driving condition (RPM, temperature of oil, pressure of oil).
3.3.2 Valve Angle at CVVT Control
Fully retard
Max advance
● Moving to retard or maintaining at fully retard condition
※ 0% Duty
● All supplied oil flow into retard chamber and all of oil in the advance chamber are exhausted.
● Maintaining middle state
※ 50% Duty
● The supplied oil does flow into neither retard chamber nor advance chamber. The oil in advance chamber/retard chamber are remained there in.
● Moving to advance or maintaining at fully advance condition
※ 100% Duty
● All supplied oil flow into advance chamber and all of oil in the retard chamber are exhausted.

3.3.3 CVVT Control Duty
(1) At the initial idle state, the 0% duty is output from OCV(Oil Control Valve), and the CVVT is in fully retard condition. The oil is only in the retard chamber.
(2) When the intake valve is needed to be open faster than now according to the driving condition, 100% duty is output from OCV and the oil is supplied to the advance chamber of CVVT. At that time, the oil in the retard chamber is come out and then the CVVT housing is moving faster than the rotor vane.
- When it reaches at target position, 50% duty is output from OCV so that the position is maintained.
(3) When the intake valve is needed to be open later than now timing accordng to the drivng condition, 0% duty is output from OCV and the oil is supplied to the retard chamber of CVVT. At that time, the oil in the advance chamber is come out and then the CVVT housing is moving later than the rotor vane.
(4) However, when the target position is at fully retard condition→if it is maintained, 0% duty is output.
When the target position is at fully advance condition → if it is maintained, 100% duty is output.
3.4 Cautions at CVVT maintenance
3.4.1 CVVT Assembly
(1) Joining method for CVVT and Camshaft

① After the pins of the camshaft are aligned to the same direction along to the CVVT timing mark, insert softly. (The cam shaft pin should be accurately inserted into the hole of the rotor vane.)
② When the pin is reached at the surface of rotor vane, press it strongly and do not rotate. (Be careful that the vane surface may be damaged because it is made of aluminum.)
③ After coat oil at the CVVT bolt, tighten it.(joining torque should comply with 5.5~6.5kgf.m.)
④ When CVVT bolt is joined, the cam shaft should be restrained but CVVT should not be restrained.
(2) Cautions at using CVVT Assembly
① Fallen component should not be used again – If it is distorted by the shock, the CVVT may not work properly
② The CVVT bolt should be jointed complying with regulated torque (5.5~6.5 kgf.m)
- When it is lighter than regulation : The rotor vane which should be fixed to the cam shaft may be rotating.
- When it is stronger than regulation: The CVVT may be distored ro bolt may be damaged.
Do not disassemble by removing the bolt or re-assemble. When it is disassembled, it should be replaced with new one.③ When CVVT Assembly is the cause
of the failure, should not disassemble
the CVVT
- As CVVT assembly is assemble by
special equipment, it it is disammebled and reassembled by unauthorized method, it may not work properly
④ Carfully clean the oil path of head, block, camshaft and CVVT Assembly
- To prevent that CVVT does not work by stucking with foreign materials in OCV
⑤ Be careful that the rotor vane has not any crack when CVVT is inserted into cam shaft (When the CVVT is not inserted into the hole of cam shaft, do not rotate the two components.)
- When the oil flowing into CVVT is leaked, it may make a bad influence on CVVT operation.
⑥ When CVVT bolt is tightened, after the cam shaft should be restrained and CVVT is installed at the head with being slightly jointed, the cam cap is assembled. And then, CVVT bolt is tightened with regulated torque after the rotation of cam shaft is restrained.
(3) Method for checking the failure on CVVT single component
① Fix the cam shaft to a bais. (Be carful that cam and journal are not damaged)
② Check whether the CVVT is rotating or not.(In normal state, it should not rotate)
③ Blank off all hole with vinyl tape, exceept one hole (near to CVVT) indicated by the black arrow in the left figure.
④ Using Air Gun, supply an air pressure of about 100kpa through the hole not blank off in ③.
- This is the operation to disassemble Lock Pin used for preventing rotation
- According to the supplied air pressure, the CVVT may be rotated automatically.
- When Air is supplied, if a lot of air is too leaked, the Lock Pin may not be disassmbled. (not sufficient for pressure to assemble Pin)
⑤ Rotate the CVVT with hand to advance direction under the condtion of ④ (the direction of red arrow in the figure).
- After the Lock Pin is disassembled, the CVVT should be rotated easily to the advnace/retard angle direction. (However, when the air pressure is released and the CVVT is returned to the initial retard angle position, if the Lock Pin is re locked, then CVVT is not moved.)
- Move about 20˚ from Max retard angle position to Max advance angle position.
⑥ If any problem is occurred, replace with new one. If there is no new product, rotate the CVVT to the Max retard angle position to lock the Lock Pin.

3.4.2 OCV(Oil Control Valve)
(1) Caution at treating OCV
① Do not use fallen component
- When the OCV is distorted by shock, the OCV may not be work
② Be clean the OCV single component
- To prevent CVVT from not working by stucking with foreign material in OCV
③ Do not operate with holding OCV sleeve
- To protect from foreign material
④ Do not displace the engine by holding the OCV yoke after OCV is assembled with engine. Do
not use the yoke as a supporting point.
- To prevent CVVT from not working by disformed OCV
⑤ When the OCV is locked by the foreign material, replace it with new one (joining torque: 1.0 ~ 1.2kg·m, Do not use it after the foreign material is removed)

3.4.3 OCV filter
(1) Caution at treating
① Be maintaingn clean during assembling operation
- To prevent CVVT from not working by locking by foreign material in OCV
② After removing it, check any chip in filter, stucking by foreign material or clogging
- If needed, clean with Air Gun or replace with new one

3.4.4 Foreign material management per CVVT single component
(1) SPEC for controlling foreign material at each component

Amount of Foreign Material
Size of Foreign Material
2 mg
Max 0.4mm
OCV filter
Oil filter ~ OCV
OCV ~ oil path of cam shaft
Internal oil path of cam shaft

(2) Caution for operating related with foreign material
① Be carful that the foreign material is not flown into oil path of the CVVT when any component relervant with CVVT is dissembled/assembled.
② When each component is removed, should clean them before re-assembling
③ Do not use cotton glove but coated glove.
Warning lamp ON
“A” Camshaft Position-Timing Over-Advanced
or System Performance(Bank 1)
Crankshaft Position-Camshaft Position Correlation
(Bank 1 Sensor A)
Intake Valve Contorol Solenoid Circuit Low (Bank 1)
Intake Valve Contorol Solenoid Circuit High (Bank 1)
Engine Oil Temp. Sensor Range / Performance
Engine Oil Temp. Sensor Low Input
Engine Oil Temp. Sensor High Input
3.5 CVVT Failure Code (DTC)

4. ETC (Electronic Throttle Control)
By controlling intake air amount and engine RPM accurately, the ETC is used for establishing the optimized driving convenience.
Due to the ETC, engine idling speed control, TCS control, Cruse control (for export) can be performed. In addition, the failure occurrence ratio can be reduced and reliability will be enhanced due to the simplified wirings and reduced connectors.
Furthermore, the exhausted gas amount could be reduced by reducing the catalytic activation and protection of catalytic, the fuel efficiency and driving convenience could be enhanced due to the optimizing of the engine torque and transmission control, and occurrence of Jerking could be prevented.

Control Items
Conventional Control Method
Theta Engine
Throttle valve control
Mechanical linking structure
(Acceleration Cable)
Unified Control by ETC
Idle speed control
Control by ISA
TCS control
(Traction Control System)
TCS control by installing assistant throttle valve
Cruse control
* cruse control using assistant accelerator cable
* cruse control using vacuum

Throttle Motor
Throttle Valve
TPS 1,2
APS 1,2

4.1 Throttle Motor
TPS 1·2
Throttle motor

It is a motor for driving the opening and closing the throttle valve by being supplied the current for operation from the engine ECM. It is comprised of coil having delta wiring and driving gear for driving rotor of coil and throttle valve. Furthermore, the TPS 1·2 is installed therein.
By referring to the learned value (operational data) of initial position of throttle motor and voltage variation of TPS value, the ECM detects the present position of the throttle motor, and controls precisely the current supplied to the motor using the duty control (PWM). In the operation of the throttle motor, the rotor is rotating in 780 degrees from full closed state to full opened state and in 30 degrees at each 1 pattern so that it can be controlled by 26 patterns totally.
When the throttle motor is in failure, the throttle valve is fixed at 5 degree, as the function of limp-
home function, to protect the engine from being stopped to be continued on driving state.

4.2 Accelerator Position Sensor
As a sensor for detecting the pressing amount of the accelerator to decide the accelerating intension of driver, the APS1·2 sensor is installed at the top portion of the accelerator pedal.

Switching point of Idle switch
Characteristics of APS output
Standard tangent (100%-100˚)
Accelerator sensor rotating angle (100˚)
Full Closed Point


4.3 Throttle Position Sensor
This is used for sending a signal to ECM by detecting the moving amount of the throttle valve.
The engine ECM plays an important role for performing a feedback control for opening the valve to wanted amount by receiving the TPS signal, and is installed inside of the throttle motor.

Throttle sensor rotating angle (˚)

4.4. Initializing Method of Throttle Body for ETC
The engine is cranked after the initializing operation should be performed under the following conditions because the ETC motor controls without sensor when the ETC is in failure and the failure elements are replaced after checking.
(1) When any vehicle line is open
(2) When the throttle actuator is replaced
(3) When the ECM is replaced
4.4.1 Initializing condition for ETC throttle body
(1) completing learning the full closing and full pressure of TPS 1·2
(2) No shorting, opening at TPS 1
(3) The throttle position feedback should be normal
(4) Normal throttle motor
(5) Normal throttle motor power
(6) Normal engine ECM
4.4.2 System checking method.
The ETC system is checked by performing the ETC system initializing according to the following process
(1) Leave for more than 10 seconds at IG Key Off state
(2) After IG key On, IG Key is Off again for about 1 second (no cranking)
(3) Leave for more than 10 seconds at IG Key Off state (up to main relay Off)
(4) Record learned value of rotor position to EPROM by performing IG Key ON again (for over 1 second), so that the initial operation is completed by above-mentioned operation.
① Check the moving of the T/Valve of the initial process by visual sight
② The method for checking the completion of the initial operation is to check the throttle valve motion by accelerator operation at the engine cranked state or IG key SW ON state.
③ If the initializing is completed at once, the initial operation is not needed any more even the battery is removed.
4.4.3 Considering Items at ETC system diagnosis and maintenance service
(1) When the T/Body is temporarily stuck by accumulating of carbon inside of the T/Body and components related with ETC has any failure in electrical connecting, the limp-home mode or engine stop will be occurred.
(2) As the DTC is always occurred when problems related with ETC is occurred, it is necessary to clean the accumulated carbon inside of the T/Body or to check the contact failure on DTC prior to replacement of T/Body or ECM.
(3) If the DTC is always detected when problems related with ETC is occurred, and it the engine is stopped when DTC is not occurred, then the other points except ETC system should be checked.
(4) When ETC system is in failure, replacing components has not to be performed.
(5) The maintenance service by precise diagnosis using ETC system should be performed.

5. EMS (Engine Management System)

Mass Air-Flow Sensor
Intake Air Temperature Sensor
Acceleration Position Sensor
Engine Coolant Temperature Sensor
Throttle Position Sensor
Camshaft Position Sensor
Crankshaft Position Sensor
Knock Sensor
Oil Temperature Sensor
Vehicle Speed Sensor
A/C Switch
Power Steering Pressure Sensor
Ignition Coil
Main Relay
Purge Control Solenoid Valve
Electronic Throttle Control Module
Oil Control Valve (CVVT)
Cooling Fan
Fuel pump
A/C Relay.


5.1 Relay (Engine Control Relay, Fuel pump Relay)
5.1.1 Engine Control Relay
It is a relay for supplying electric power to engine ECM and system elements. When the ignition switch is ON, the battery voltage is supplied from the ignition switch to engine ECM. At that time, the engine ECM drives main relay (main relay field winding is grounded) and then the main relay supplies
the electric power to engine ECM, fuel pump relay, other relays, actuators and sensors.
Engine Control relay diagnosis (P0562 P0563)
(1) Decision condition for failure: when wire is shorted or broken or the cranking is not started
(2) Remedy for failure : No (engine is stopped, Re-start is impossible)
(3) Checking the circuit of single component of main relay and connector and operation optionally.
5.1.2 Fuel pump Relay
It is a relay for supplying power to fuel pump and is driven by engine ECM. The engine ECM decides to drive the fuel pump relay in accordance with the signal of CKP sensor.
Fuel pump relay diagnosis (P0230)
(1) Decision condition for failure: when wire is shorted or broken or the cranking is not started
(2) Remedy for failure : No (engine is stopped, Re-start is impossible)
(3) Checking the circuit of single component of main relay and connector and operation optionally.

5.2 Injector
5.2.1 Function

Delivery Pipe
DamperInjector is a ejection nozzle comprising solenoid valve so it ejects the fuel to cylinder according to the appropriate pulse signal for engine condition from ECM. As the orifices of all injectors are the same size and the fuel pressure is maintained regularly, the injected amount is decided by the opening time of the needle valve, that is the time during the solenoid is magnetized. Standard fuel injecting amount is decided by the mapped value by the air amount and engine rpm, the fuel amount could be modulated when A/F ratio signal, fuel vaporized gas control, learned fuel amount, warm-up control, catalyst heating control, fuel amount control in reduced speed, idling control, fuel increasing with full load, fuel increasing at accelerating, or re-start is occurred. As a safety function, when the engine rpm is more than 6800rpm, fuel injection is prohibited.
5.2.2 Operating principle of Injector
Injector is an ejecting nozzle including solenoid valve supplying fuel according to the ejecting signal from ECM. Injector is installed at each rear side of each intake valve of the intake manifold and connected to the fuel distribution pipe. As the needle valve is in one body with plunger, the needle valve can be pulled opening position with the plunger to be open when the injector is operated. Main signal for deciding the opening time is map sensor and engine rpm and is compensated by the signal of TPS, battery voltage, ATS, WTS and oxygen sensor. The electric power for injector is supplied from main relay.
Coil Resistance
13.8 ~ 15.2 Ω

5.2.3 Checking Waveform
In normal state, battery voltage is applied. When ECM drives injector (it is grounded), the voltage is close to 0V (theoretically 0V) and fuel is sprayed through out the injector. When the engine control releases the ground, the injector is closed, and an instant peak voltage is occurred. The peak voltage and injected fuel amount (injector opening time) at all cylinder are the same when the vehicle is driven in constant speed without any acceleration and deceleration (Injector voltage waveform)
5.2.4 Failure Code and Decision Condition
Standard Value
for Failure Decision
1) Low output signal
- Signal line is short to ground
2) High output signal
- Signal line is short to battery, B+
3) No signal
- Signal line is open
Failure Code
#1 – P0261_P0262
#2 – P0264_P0265
#3 - P0247_P0248
#4 – P0270_P0271
Failure Detecting time
- Immediately (Failure code is saved)

Engine condition at signal line short
- When connector is removed,
misfire is occurred

Other Limitations
1) Prohibition of A/F control feedback (prohibition of Lambda control)
2) Limiting in purge control
3) Prohibition of fuel amount learning
4) Prohibition in monitoring the idle adjusting valve

(1) Remedies of engine ECM at injector failure
① Sequential injecting is started
② Prohibition of control the failure injector
(2) Failure Diagnosis
① Using scan tool, self-diagnosis/sensor output can be performed.

Diagnosis Condition
Normal value
Temperature of engine cooling water: 80~90 ℃
Lamps, components of electric fan: all OFF
Transmission: Neutral position
Steering wheel: in not operated state
3 ~ 5 ms
Quick Acceleration
Quick Deceleration

② Test for injector driving forced
③ Checking for the resistance of the injector current: about 13Ω ~ 16Ω at 20℃ (nominal value 14.5±0.35Ω)
Deviation of the resistance between injectors should be less than 0.7Ω
- Measuring and checking the injector voltage waveform

5.3 Purge Control Solenoid Valve
5.3.1 Function
The purge control solenoid valve is duty control type and controls the inflow of purge air from canister. Vaporized gas from the fuel tank is gathered at canister and then the engine intakes the vaporized gas again to use.
The 12V power is supplied from the main relay to the purge control solenoid valve and, the ECM operates the valve by contacting to ground at operating condition. When the purge control valve is operated in low speed or high speed, it can influence to the engine output so that it should perform the duty control at middle speed. Neither when the cooling water is low.

5.3.2 Failure Diagnosis
(1) Checking short and open (P0444 P0445)
(2) Checking the failure using diagnosis equipment (Self-diagnosis), the warning lamp is not lightened
(3) Checking the forced driving sound
5.3.3 Failure Diagnosis and Decision Condition
Failure Code
Decision Condition & Fail safe
Checking Item
Purge Control Solenoid Valve (PCSV) circuit failure – low voltage
Decision Condition
DTC Decision Method
- Checking opened line or shorting ground
Open, Short
Possible Condition
- 10V ≤ battery voltage ≤ 16V
Decision value
- Checking opened line or shorting ground
Purge Control Solenoid Valve (PCSV) circuit failure – high voltage
Decision Condition
Circuit Open
DTC Decision Method
- Signal line is short to battery, B+
Possible Condition
- 10V ≤ battery voltage ≤ 16V
Decision value
- Signal line is short to battery, B+
5.4 A/F Ratio Compensation
One of the most typical methods for fuel amount compensating in the vehicle equipped with ECM is the A/F ratio compensation. The A/F ratio compensation can make an error in real A/F ratio even if the engine ECM injects fuel perfectly according to the information from every sensor.
Therefore, an oxygen sensor should be installed at exhaust manifold to measure the ration between air and fuel and send back it to engine ECM. The engine ECM receives the signal from the oxygen sensor and then compensates the fuel injecting amount to satisfy to the theoretical A/F ratio. The main purpose of the A/F ratio feedback is to enhance the purification efficiency. If any sensor or output element, which can influence the purification efficiency is in failure, then the A/F ratio feedback is prohibited.
5.4.1 Condition for A/F ratio feedback
- When the pressure is higher than 280mb and lower than 927mb
- When the variation of pressure is lower than 18mb
- When the engine rpm is higher than 1184mb and lower than 5800mb
- When the temperature of intake air is higher than 20℃
- Oxygen sensor, PCV, MAP, WTS, and ATS should be in normal state (When the influences are not resulted from the failure)
- When the temperature of the cooling water is higher than 70℃
- PCV should not operated
- When the above-mentioned conditions are satisfied and A/F ration learning condition is performed
5.4.2 When the A/F ratio feedback control can not be performed
- Pre-selected data
- Engine RPM
- Data of vehicle having at last
- When the temperature of cooling water is higher than 70℃
The engine ECM controls the A/F ratio based on the above-mentioned items (OPEN LOP CONTROL).
As related failure diagnosis, based on the input/output sensor, exhaust system leakage, fuel line system (fuel pump, pressure adjuster, fuel tank, delivery pipe) and other systems (ignition coil, spark plug, cable) are checked as well as the vaporized gas control system (canister, PCV) should be checked.

5.4.3 Failure Code and Decision Condition
Decision Condition & Fail safe
Checking Item
Feedback Learning Failure
A/F ratio addition compensation (lean)
Decision Condition
Relevant Sensor
Intake System
Fuel Pressure
DTC Decision Method
- addition compensation amount
Possible Condition
- Cooling water temperature > 70℃
- Intake air temperature
- Throttle angle is not in full load state
- Purge control is not worked
- Feedback control is worked
- Feedback compensation control
- Engine RPM < 1040 rpm
- Air amount < 14kg/h
Decision value
- Addition compensation element > 7.5%
Feedback Learning Failure
A/F ratio additional compensation (rich)
Decision Condition
Relevant Sensor
Intake System
Fuel Pressure
DTC Decision Method
- addition compensation amount
Possible Condition
- Cooling water temperature > 70℃
- Intake air temperature
- Throttle angle is not in full load state
- Purge control is not worked
- Feedback control is worked
- Feedback compensation control
- Engine RPM < 1040 rpm
- Air amount < 14kg/h
Decision value
- Addition compensation element < 7.5%
Feedback Learning Failure
A/F ratio multiplication compensation (lean)
Decision Condition
Relevant Sensor
Intake System
Fuel Pressure
DTC Decision Method
- multiplication compensation amount
Possible Condition
- Cooling water temperature > 70℃
- Intake air temperature
- Throttle angle is not in full load state
- Purge control is not worked
- Feedback control is worked
- Feedback compensation control
- 1120 rpm< Engine RPM < 1040 rpm
- 22kg/h < Air amount < 90kg/h
- 30% < relevant load < 70%
Decision value
- Multiplication compensation element > 1.25%
Feedback Learning Failure
A/F ratio multiplication compensation (rich)
Decision Condition
Relevant Sensor
Intake System
Fuel Pressure
DTC Decision Method
- multiplication compensation amount
Possible Condition
- Cooling water temperature > 70℃
- Intake air temperature
- Throttle angle is not in full load state
- Purge control is not worked
- Feedback control is worked
- Feedback compensation control
- 1120 rpm< Engine RPM < 1040 rpm
- 22kg/h < Air amount < 90kg/h
- 30% < relevant load < 70%
Decision value
- Multiplication compensation element > 1.25%