Diagnostic Information & Procedures: Backfire

Backfire

Checks	Action
DEFINITION: The fuel ignites in the intake manifold, or in the exhaust system, making a loud popping noise.
Preliminary Check	Refer to Diagnostic System Check - Engine Controls . Refer to Symptoms - Engine Controls .
Ignition System Checks	Check for adequate ignition coil voltage with a J 26792 spark tester or equivalent. Refer to Electronic Ignition (EI) System Diagnosis . Check the spark plugs for correct operation and performance. Refer to Spark Plug Inspection . Check for the correct ignition timing. Refer to Ignition System Timing Adjustment Procedure .
Engine Mechanical Checks	Check for any of the following engine mechanical problems: An incorrect valve lash Any broken or weak valve springs A low compression Any sticking or leaking valves An incorrect valve timing An incorrect or worn camshaft Refer to Engine Compression Test in Engine Mechanical - 2.0L. Check the intake and exhaust system for casting flash or other restrictions.
Additional Checks	Check for the proper fuel pressure. Refer to Fuel System Diagnosis . Verify the PCM grounds are clean, tight, and in the proper locations. Refer to Engine Controls Schematics Power and Ground. Check the Service Bulletins for any updates or information.