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?
Yes
>> Go to the next step.
No
>> Repair as necessary. Verify symptom no longer exists.
2.
CHECK ECM DTC
• Turn the ignition switch on.
• With the X-431 scan tool, select view DTC and stream data in ECM.
Are there any DTCs present?
Yes
>>
Check for causes.
See Diagnostic Trouble Code (DTC) index — Engine Control Module (ECM).
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?
Yes
>> 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?
Yes
>> Go to the next step.
No
>>
Repair as necessary.
Verify the symptom no longer exists.
ELECTRONIC ENGINE CONTROLS - ENGINE SYMPTOM DIAGNOSIS
03
03–191
Chery Automobile Co., Ltd.
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