Backfire. Pontiac Sunfire 2002

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 2002 🢒 Sunfire 🢒 Engine 🢒 Engine Controls - 2.2L (LN2) 🢒 Backfire

Backfire

Checks

Actions

DEFINITION: The fuel ignites in the intake manifold or in the exhaust system, making a loud popping noise.

Preliminary Checks

•	Refer to Diagnostic System Check - Engine Controls .

•	Refer to Symptoms - Engine Controls .

•	Search for service bulletins.

Fuel System

•	Inspect for low fuel pressure. Refer to Fuel System Diagnosis .

•	Inspect for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

•	Ensure that each injector harness is connected to the correct injector/cylinder. Refer to Engine Controls Schematics .

Ignition System

•	Ensure proper ignition voltage output with the J 26792 Spark Tester or equivalent.

•	Inspect the spark plugs for the following conditions:

-	Wet or fuel fouled spark plugs

-	Cracks on the spark plugs

Wear

-	Improper spark plug gap

-	Burned electrodes or heavy deposits

•	If the spark plugs are fuel or oil-fouled, determine the cause of the fouling before replacing the spark plugs.

•	Inspect the ignition control module (ICM) for proper ground connection.

•	Inspect the ignition coils for cracks or carbon tracking.

•	Inspect the spark plug wires for proper resistance and condition.

Engine Mechanical

•	Inspect the engine mechanical for the following conditions:

-	Incorrect compression

-	Sticking or leaking valves

-	Worn camshaft lobes

-	Incorrect valve timing

-	Bent push rods

-	Worn rocker arms

-	Broken valve springs

-	Excessive oil in combustion chamber due to leaking valve seals

-	Low cylinder compression

•	Inspect for incorrect basic engine parts. Inspect the following components:

-	The camshaft

-	The cylinder heads

-	The pistons

-	Other engine parts, as appropriate

•	Refer to Diagnostic Starting Point - Engine Mechanical in Engine Mechanical-2.2L.

Additional Checks

•	Inspect the intake and exhaust manifolds for casting flash. Refer to Symptoms - Engine Mechanical in Engine Mechanical-2.2L.

•	Inspect the exhaust system for a possible restriction. Inspect the following conditions:

-	The exhaust system for damaged or collapsed pipes.

-	The mufflers for heat distress, or for possible internal failure.

-	A possible plugged three-way catalytic converter (TWC). Refer to Restricted Exhaust in Engine Exhaust.