Chery A15. Manual — part 275

The fuel injection system and throttle body used by the engine already feature fuel circuit
system and fuel-air premixing function. Therefore, the throttle is far less polluted than
traditional throttles. Its simple structure also makes it easier for maintenance. The
cleaning procedure is as follows:
(1) Connect the diagnostic instrument and start up the engine. Stop the engine when
water temperature is above 75℃.
(2) Unfix the air intake pipe connected with the throttle.
(3) Clean away the dust on the throttle body with compressed air (Figure 18-9). Clog the
idle speed bypass hole of the throttle (Figure 18-10) and spray the detergent.
(4) Slightly open the throttle and start and accelerate the engine 5 minutes later. In order
to avoid unstable idle speed or flameout, the throttle may be slightly opened to run the
engine at stable idle speed.
(5) Shut off engine: repeat the above procedure if the dirt is not cleaned away.
(6) Resume the idle speed bypass hole.
(7) Clear off the troubleshooting codes displayed on the diagnostic instrument.
(8) Start the engine and check if it is running normally.









Figure 18-9 Throttle Body

Figure 18-10 Idle Speed Bypass Hole Location

Throttle air intake
side

Idle speed bypass
hole

Five. Maintenance tool
1. Unfixing electrical control system components – unfixing tools for common
mechanical components of vehicle
2. Circuit of the electrical control system and electrical signals of the system – digital
multimteter (with a buzzer);
3. Troubleshooting on electrical control system and checking engine working status;
- Diagnostic instrument for vehicle electrical control system faults (recommended);








4. Fuel pressure gauge, measuring range 0-800kPa

Six. Troubleshooting on engine by diagnostic instrument data flow
Step 1:
1) Engine room wire harness and vacuum pipeline
- Possibly affect the system’s control over air flow and fuel supply quantity
2) Fixing of oxygen sensor and three-way catalyst
- Possibly affect the system’s judgment on AFR and reduce the transformation efficiency
of the three-way catalyst.
3) Engine fault indicator light
- Affect the system’s warning of faults
4) Storage battery voltage
- Judge if the storage battery has sufficient power.
5) Rely on experience to judge if the cooling fluid temperature sensor, air intake
temperature sensor, air intake manifold absolute pressure sensor and oxygen sensor
display normal values
6) Working scope of the throttle position sensor
- If the throttle can’t be fully opened or closed, the engine performance and some of the
system functions may be affected.
Step 2
1) Idle speed control valve reset
- Turn off the key switch and observe the idle speed stepping. Abnormal stepping may
affect the next startup of the engine.
2) If the ECM power supply is cut off
- The communication between the diagnostic instrument and the system stops after the
key switch is turned off.
Step 3
1) Cooling fluid temperature and cooling fluid temperature cycle
- Indicate if the thermostat is working properly.
2) Storage battery voltage














- Indicate if the engine is working properly: possibly engine adjustor fault: possibly
improper engine wiring or engine fault.
3) Air intake manifold pressure

- Indicate if there is any leakage or valve clearance is too small. The pressure is higher if
the valve clearance is too small. In this case, the engine performance will be affected and
the life span of the oxygen sensor and the three-way catalyst may be reduced due to
advance opening of the throttle and exhaust temperature rise; the pressure is lower if the
valve clearance is too big. In this case, the system’s judgment of the engine working
status will be affected and abnormal idle speed during vehicle heating will be resulted.
In addition, in the case of clogged exhaust system, e.g. foreign matters in the exhaust
pipeline, blocked three-way catalyst due to over consumption of engine oil and broken
components internally, overpressure will be resulted.
1) Idle speed motor position
- If this value is too low, there may be air leakage into the air intake system; if it is too
high, then the throttle body and idle speed control valve may be partially blocked with oil
dirt and need cleaning.
2) Cycling times of oxygen sensor value
- If the cycling times are not enough, the oxygen sensor may have failed.



Seven. Simple troubleshooting method

Please follow the following steps while repairing the engine management system. If the
fault is fixed in a particular step, then the subsequent steps can be omitted. Then use the
diagnostic instrument to check if the fault has been eliminated and clear off the
troubleshooting code. The storage battery voltage shall not be lower than 8.5V when the
diagnostic instrument is being used.


















Eight. Typical troubleshooting method

Fault 01

Communications between the diagnostic instrument and the system is

disabled

Possible cause

Reference maintenance scheme

1) Loosened diagnostic wiring
2) Diagnostic instrument functions do not
comply with the system
3) Diagnostic instrument fault
4) Diagnostic interface and ECM terminals do
not match each
5) Open circuit of relevant circuit to the
diagnostic interface
6) ECM communication fault

1) Fix the terminals again
2) Use the diagnostic instrument that
complies with the vehicle and the system
3) Eliminate diagnostic instrument fault
4) Repair the wire harness

5) Repair the wire harness

6) Replace the ECM

Fault 02

Startup is disabled

Possible cause

Reference maintenance scheme

Fault indicator light:
1) Off
- Broken fuse
- Ground fault
- ECM terminal
- Light bulb and wiring
- ECM fault
2) On
- Check with the diagnostic instrument
- There is troubleshooting code
- There is no troubleshooting code

1)
- Replace
- Check and resume
- Fix again
- Repair wire harness and light bulb
- Replace the ECM
2) Use a diagnostic instrument
- Eliminate the fault
- Check the system power supply, signal
collection system, fuel supply system,
ignition system, idle speed control
system, engine and vehicle mechanical
system

System power source:
1) System voltage while starter is in operation
- < 8V
- > 8V

1) Use the diagnostic instrument
- Replace the storage battery or charge
- Check other systems

Continued

Signal collection system:
1) There is no turning speed data flow

1)