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

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

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Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

1. Perform a bulletin search.
2. If you find a bulletin that addresses the symptom, correct the condition as instructed in the bulletin.

Did you find a bulletin that addresses the symptom?

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Go to Step 11

Go to Step 3

Perform the careful visual/physical checks as described at the start of the Symptoms section.

Did you perform the visual/physical check?

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Go to Step 4

Go to Important Preliminary Checks

1. Check for a proper ignition coil output voltage with the spark plug jumper wires J 36012 and the spark tester J 26792.
2. If a problem is present, repair the problem as necessary.

Was a repair necessary?

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Go to Step 11

Go to Step 5

Notice: If spark plugs are gas or oil fouled, determime the cause of the fouling before replacing the spark plugs in order to avoid damage to the new spark plugs.

1. Remove the spark plugs and check for the following conditions:

•

Wet plugs

•

Cracks

•

Wear

•	An improper gap

•	Burned electrodes

•	Heavy deposits

2. If a problem is present, repair the problem as necessary.

Was a repair necessary?

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Go to Step 11

Go to Step 6

1. Check the fuel pressure. Refer to Fuel System Diagnosis .
2. If a problem is present, repair the problem as necessary.

Was a repair necessary?

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Go to Step 11

Go to Step 7

1. Perform the Fuel Injector Solenoid Coil Test and Fuel Injector Balance Test .
2. Replace any malfunctioning injector.

Were any injector(s) replaced?

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Go to Step 11

Go to Step 8

1. Check engine mechanical for the following conditions. Refer to Engine Mechanical for the diagnostic procedures.

•	Low compression

•	Sticking or leaking valves

•	Worn camshaft lobe(s)

•	Incorrect valve timing

2. If a problem is present, repair the problem as necessary.

Was a repair necessary?

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Go to Step 11

Go to Step 9

1. Check the intake and the exhaust manifold(s) for casting a flash. Refer to Engine Mechanical .
2. If a problem is present, repair the problem as necessary.

Was a repair necessary?

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Go to Step 11

Go to Step 10

1. Review all of the diagnostic procedures within this table.
2. If all of the procedures have been completed and no malfunctions are present, visually/physically inspect the following items:

•	The scan tool data

•	All of the electrical connections within a suspected circuit and/or system

3. If a problem is present, repair the problem as necessary.

Is the action complete?

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Go to Step 11

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Operate the vehicle within the conditions under which the original symptom was observed.

Does the system now operate properly?

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System OK

Go to Step 2