Chery A18. Manual — part 38

FUEL AND EMISSION CONTROL SYSTEMS

INTAKE-AIR SYSTEM

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D-2

INTEGRAL INTAKE MANIFOLDS

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THROTTLE BODY

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IDLE SPEED STEP MOTOR

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THROTTLE POSITION SENSOR

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INTEGRAL AIR PRESSURE/TEMPERATURE SENSOR

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ASEEMBLY AND DISASSEMBLY OF INTAKE SYSTEM

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CANISTER SOLENOID AND INTAKE/EXHAUST PIPE

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OIL-VAPOR SEPARATOR

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EXHAUST SYSTEM

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D-9

OUTLINE

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OXYGEN SENSOR

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ASSEMBLY AND DISASSEMBLY OF EXHAUST SYSTEM

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FUEL SYSTEM

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ASSEMBLY AND DISASSEMBLY OF FUEL SYSTEM

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OPERATION CONTROL OF ENGINE FUEL SUPPLY SYSTEM

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D-19

FUEL SYSTEM WORKING COMPONENTS

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D-21

INTAKE-AIR SYSTEM

INTEGRAL INTAKE MANIFOLDS

Warning：

·When the engine and intake-air system are hot, they can badly burn. Turn off the

engine and wait until they are cool before removing the intake-air system.

·Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage.

Always keep sparks and flames away from fuel.

·Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or

death and damage. Fuel can also irritate skin and eyes. To prevent this, always
complete the “Fuel line safety Procedure”

1.Throttle Cable Supporter 2. Throttle Body 3. Idling Speed Step Motor

4. Throttle Position Sensor 5. Canister Solenoid Valve 6. Coolant Temperature Sensor

7.Fuel Injector 8. Oil Rail 9. Air Pressure/Temperature Sensor

THROTTLE BODY

According to driver’s stepping force on accelerating pedal, throttle body fixed on intake
manifolds with three bolts, measures air intake volume flowed into the engine. Step motor
adjusts the auxiliary air intake volume when pedal completely released (engine at idle). In
this case, throttle valve opening control handle (3) relies on the anti-deadlock screw (2) to
keep throttle valve from closing.

To avoid the mixture condensing and freezing in certain condition, throttle valve adjuster is
supported by anti-deadlock screw to prevent it from completely closing, and heated by
circulating coolant. Idling speed step motor (4) and throttle position sensor (5) are installed
on throttle body.

1.Throttle Cable Supporter 2.Anti-deadlock Screw
3.Throttle Valve Opening Angle Control 4.Idling Speed Step Motor
5.Throttle Position Sensor
Remark: Do not loosen the screw because the anti-deadlock screw is locked by
manufacturer during calibration of throttle valve.

IDLE SPEED STEP MOTOR

This kind of idling speed step motor (±25r/m) with high accuracy and good locating ability is
used to control idle speed. Directly fixed on throttle body and composed of a step motor and a
screw/worm retarder, it enables the lock pin (3) to convert the rotation motion into linear
motion. When receiving control instruction from ECU, the step motor drive valve core
moving (about 0.04mm/step) on axis direction through screw/worm device to change the
bypass air intake volume of engine at idle, therefore the idle speed can be insured steady. The
change is regulated based on the engine coolant temperature.

Air intake efficiency of the engine at idle speed is demarcated based on opening of the
throttle valve when by-pass air intake is closed through adjusting in manufacturing.

Step motor is connected directly on throttle body by a fast clamp without fixing screw.

1.Idling Speed Step Motor 2. By-pass Hose 3. Lock Pin 4. Throttle Valve

5. Throttle Body 6. ECU Electrical Control Unit 7.Steel Lock Ring

Qo. Air Leakage Volume Of Throttle

Q. By-pass Air Volume Of Step Motor

Specification:

The coil resistance is R=53 ± 10Ω at 20℃. A max air intake volume will be got when the
lock pin turns back 200 steps (approx 8mm stroke, correspond to about 60kg/h air intake
volume).

Working steps are determined according to the engine running condition, including heater
opening and electrical load air condition opening etc.

Batter terminal shall be disconnected for at least 5 minutes before inserting idling speed step
motor into the throttle body. Accordingly, when the key opened, ECU will reset a new step
motor and define steps according to the coolant temperature to adjust the valve core’s axial
moving (forward or backward) with a correct idle speed.

Electronic components can be diagnosed by engine ECU. Through regulating the throttle
valve position, with engine speed and intake pressure signals, the engine ECU can detect
whether the step motor (tested by a diagnosis tester) loses step or not.

Recovery:

If a failure happens, step motor will become invalid, correspondingly the adaptive function of
air fuel ratio at idle is ceased.