6E1-98 DRIVEABILITY AND EMISSIONS
Backfire Symptom
Step Action Value(s) Yes No
DEFINITION: Fuel ignites in the intake manifold, or in the exhaust system, making a loud popping noise.
1
Was the On-Board Diagnostic (OBD) System Check
performed? -
Go to Step 2
Go to OBD
System
Check
2
1. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom?
-
Verify repair Go to Step 3
3
Was a visual/physical check performed?
-
Go to Step 4
Go to
Visual/Physic
al Check
4
Check for proper ignition voltage output with the spark
tester (Use commercially available tool).
Was a problem found?
-
Verify repair Go to Step 5
5
1. Remove the spark plugs and check for gas or oil
fouling cracks, wear, improper gap, burned electrodes
of heavy deposits.
2. If spark plugs are fouled, the cause of fouling must be
determined before replacing the spark plugs.
Was a problem found?
-
Verify repair Go to Step 6
6
1. Visually/Physically inspect the secondary ignition wires.
Check for the following conditions:
• Verify that all ignition wire resistance are less than the
specified value.
• Verify that ignition wires are correctly routed to eliminate
cross-firing.
• Verify that ignition wires are not arcing to ground.
Spraying the secondary ignition wires with a light mist of
water may help locate an intermittent problem.
Was a problem found?
-
Verify repair Go to Step 7
7
Check for an intermittent ignition system malfunction:
• Intermittent CKP 58X signal.
• Intermittent ignition feed circuit or sensor ground circuit
to the crankshaft position sensor.
Was a problem found?
-
Verify repair Go to Step 8
8
Refer to Fuel System Diagnosis to determine if there is a
problem with fuel delivery.
Was a problem found?
-
Verify repair Go to Step 9
9
Check for the following engine mechanical problems:
• Low compression
• Leaking cylinder head gasket
• Worn or incorrect camshaft
• Incorrect valve timing
• Sticking or leaking valves
• Camshaft drive belt slipped or stripped.
Was a problem found?
-
Verify repair Go to Step 10
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