Page 840 of 1903

Downloaded from www.Manualslib.com manuals search engine Back Fires
The following conditions apply to this symptom:
•The engine will back fire when operated.
• The engine back fire occurs at all operating parameters.
1.PRELIMINARY CHECKS
• Carry out the following preliminary checks:
Vacuum lines (check for damage and correct routing).
Spark plug wire routing (correct firing order).
Are all checks OK?
Ye s>>Go to the next step.
No
>>Repair as necessary.
Verify the symptom no longer exists.
2.CHECK ECM DTC
• Turn the ignition switch on.
• With the scan tool X-431, select view DTC and stream data in ECM.
Are there any DTCs present?
Ye s>>See the Diagnostic Trouble Code (DTC) List.
Go to the specific diagnostic test to troubleshoot the DTC.
No
>>Go to the next step.
3.CHECK SECONDARY IGNITION SYSTEM
• Perform the following to test the secondary ignition system:
Disconnect the injector fuse.
Remove any of the 4 spark plugs.
Connect the spark plug to spark plug wire.
Ground the spark plug on the cylinder block.
Crank the engine to test the secondary ignition system with the spark plugs removed.
Is a strong blue spark visible at each spark plug while cranking the engine?
Ye s>>Go to the next step.
No
>>Check Camshaft Position (CMP) sensor signal at ECM.
If CMP sensor is OK, check the following:
Crankshaft Position (CKP) sensor malfunction
Spark plug wires
Spark plugs
4.CHECK FUEL QUALITY
• Check fuel quality (concerns such as correct octane, contamination).
Is the fuel quality OK?
Ye s>>Go to the next step.
No
>>Repair as necessary.
Verify the symptom no longer exists.
ELECTRONIC ENGINE CONTROLS - 2.4L ENGINE SYMPTOM DIAGNOSIS
03–556Chery Automobile Co., Ltd.
Page 842 of 1903

Downloaded from www.Manualslib.com manuals search engine Engine Poor Driveability
The following conditions apply to this symptom:
•Engine stalls/quits, engine runs rough, misses, buck/jerk, hesitation/stumble acceleration, surges, rolling idle.
• Engine stops unexpectedly at beginning of acceleration or during acceleration.
• Engine stops unexpectedly while cruising.
• Engine speed fluctuates during acceleration.
• Engine misses during acceleration.
• Vehicle bucks/jerks during acceleration, cruising or deceleration.
• Momentary pause during acceleration.
• Momentary minor loss in engine output.
1.PRELIMINARY CHECKS
NOTE :
Be aware of the over RPM limiting functions of the ECM.
• Carry out the following preliminary checks:
Fuel quality
Vacuum lines (check for damage and correct routing)
Intake air system (check for damaged tubes and dirty air filter)
Vehicle wiring (disconnected, corroded/damaged)
Throttle linkage.
Radiator (obstructed)
Transaxle
Are all checks OK?
Ye s>>Go to the next step.
No
>>Repair as necessary.
Verify the symptom no longer exists.
2.CHECK FOR STALL AT IDLE
• Check for engine stall at idle.
NOTE :
Confirm that proper vehicle maintenance has been performed before continuing with engine diagnosis.
• Inspect the following components:
Clean the injectors
Fuel filter
Intake air filter
Throttle body
Spark plugs
Spark plug wires
Does the engine now stall at idle?
Ye s>>Repair as necessary.
No
>>Go to the next step.
ELECTRONIC ENGINE CONTROLS - 2.4L ENGINE SYMPTOM DIAGNOSIS
03–558Chery Automobile Co., Ltd.
Page 843 of 1903

Downloaded from www.Manualslib.com manuals search engine 3.CHECK FOR ROUGH IDLE
• Check for engine rough idle.
NOTE :
Confirm that proper vehicle maintenance has been performed before continuing with engine diagnosis.
• Inspect the following components:
Clean the carbon deposit on intake and exhaust valves
Valve stem
Spark plugs
Throttle body
Spark plugs and combustion chamber
Does the engine idle rough?
Ye s>>Repair as necessary.
No
>>Go to the next step.
4.CHECK ECM DTC
• Turn the ignition switch on.
• With the scan tool X-431, read the DTC.
Are there any DTCs present?
Ye s>>Repair as necessary.
No
>>Go to the next step.
5.CHECK THE ELECTRONIC THROTTLE CONTROL (ETC) ACTUATOR
• Start engine and let idle.
• While checking for RPM drop or engine stall, disconnect ETC actuator connector.
Did RPM drop or engine stall when the ETC connector was disconnected?
Ye s>>Connect ETC actuator connector.
Go to the next step.
No
>>Repair as necessary.
ELECTRONIC ENGINE CONTROLS - 2.4L ENGINE SYMPTOM DIAGNOSIS
03
03–559Chery Automobile Co., Ltd.
Page 844 of 1903