Section 4 (Engine Control System (Troubleshooting & Diagnosis) - 1.8L (LV6)): Troubleshooting: Backfire

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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 the proper ignition coil output voltage with a J 26792 Spark Tester or equivalent. Inspect the spark plugs for correct operation and good ignition system performance. Refer to Spark Plug Inspection . Inspect the ignition coil boots for damage.
Engine Mechanical Checks	Check for any of the following engine mechanical problems: Broken or weak valve springs Low compression Sticking or leaking valves Incorrect valve timing Incorrect or worn camshaft Refer to Engine Mechanical. Check the intake and the exhaust system for casting flash or other restrictions.