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

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

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Go to Step 2

Go to the Powertrain On Board Diagnostic (OBD) System Check

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

Did you find a bulletin that addresses the symptom?

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Go to Step 8

Go to Step 3

Did you perform a visual/physical check?

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Go to Step 4

Go to Symptoms

1. Check for an intermittent ignition system malfunction:

•	Check the primary connections at the ignition coil assembly.

•	Check for any intermittent connections at the Crankshaft Position sensor.

2. If a problem is present, repair as necessary. Refer to Engine Electrical, and Troubleshooting Procedures for the proper procedure. Also, refer to Checking Terminal Contact in Engine Control Module Diagnosis .

Did you find a problem?

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Go to Step 8

Go to Step 5

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

Did you find a problem?

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Go to Step 9

Go to Step 7

1. Check for the following Engine Mechanical problems:

•	Low compression

•	Sticking valves

•	A hydraulic valve lifter problem

•	Leaking cylinder head gaskets

•	A worn or incorrect camshaft

•	Incorrect cam timing

•	A damaged timing belt

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

Did you find a problem?

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Go to Step 8

Go to Step 7

1. Review all of the diagnostic procedures within this table.
2. If all of the procedures have been completed and no malfunctions have been found, review/inspect the following:

•	The scan tool data

•	The Freeze Frame data

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

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

Did you find a problem?

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Go to Step 8

Go to Step 3

Operate the vehicle under the same conditions (as closely as possible) as when the original symptom occurred.

Is the original symptom still present?

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Go to Step 3

Go to Step 9

Are any other driveability symptoms still present?

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Go to Symptoms

System OK