For 1990-2009 cars

Inspections | Actions
--- | ---
DEFINITION: Fuel ignites in the intake manifold or in the exhaust system, making a loud popping noise.
Preliminary Inspections |

• | Refer to Important Preliminary Inspections Before Beginning in Symptoms - Engine Controls .

• | Search for bulletins.

• | Inspect the powertrain control module (PCM) grounds for being clean, tight, and in the proper locations. Refer to Power and Grounding Component Views and Engine Controls Schematics .

Fuel System |

• | Test for incorrect fuel pressure. Refer to Fuel System Diagnosis .

• | Inspect for a restricted fuel filter. Refer to Fuel System Diagnosis .

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

• | Test the fuel injectors. Refer to Fuel Injector Diagnosis .

• | Verify that each injector harness is connected to the correct injector or cylinder. Relocate injector harnesses as necessary.

Sensor/System |

• | Inspect the crankcase ventilation system for proper operation.

• | Monitor the knock sensor (KS) system for excessive spark retard activity with a scan tool. Refer to Scan Tool Data List .

Ignition System |

• | In order to properly inspect the spark plugs or to correct a condition, refer to the following procedures:

- | Ignition System Specifications

- | Spark Plug Replacement

- | Spark Plug Inspection

• | Remove spark plugs and inspect for the following:

- | Correct heat range

- | Wet plugs

- | Cracks

- | Wear

- | Improper gap

- | Burned electrodes

- | Heavy deposits

- | Verify that the spark plugs are of the correct type.

- | Inspect for proper ignition voltage output with J 26792 HEI Spark Tester .

• | An improper spark plug gap will cause a driveability condition. Gap the spark plugs using a wire gauge gap tool.

• | If the spark plugs are found to be fouled, determine the cause before replacing the spark plugs.

• | Inspect for damaged or misaligned spark plug boots.

• | Monitor the Misfire Current Counters while driving the vehicle in the conditions that the symptom occurred. If a misfiring cylinder can be located, use the DTC P0300 table for diagnosis. Refer to DTC P0300 .

Engine Cooling System |

• | Inspect the engine coolant level for being low. Refer to Loss of Coolant .

• | Inspect the engine thermostat for proper operation and for the correct heat range. Refer to Thermostat Diagnosis .

Engine Mechanical |

• | Inspect engine mechanical for the following:

- | Compression

- | Sticking or leaking valves

- | Worn camshaft lobes

- | Valve timing

- | Worn rocker arms

- | Broken valve springs

- | Excessive oil in combustion chamber or leaking valve seals.

- | For more information, refer to one or more of the following procedures:

• | Engine Compression Test

• | Symptoms - Engine Mechanical

• | Oil Consumption Diagnosis

• | For incorrect, worn, or damaged basic engine parts. Inspect the following:

- | The camshaft--Refer to Camshafts Cleaning and Inspection .

- | The cylinder heads--Refer to Cylinder Head Cleaning and Inspection .

- | The pistons, etc.--Refer to Piston, Connecting Rod, and Bearing Cleaning and Inspection .

Additional Inspections |

• | Visually and physically inspect the vacuum hoses for splits, kinks, and proper connections and routing as shown on the Vehicle Emission Control Information label.

• | Inspect the intake manifold and the exhaust manifold passages for casting flash.

• | Inspect the exhaust system for possible restrictions. Inspect the following:

- | Inspect the exhaust system for damaged or collapsed pipes.

- | Inspect the mufflers for heat distress or possible internal failure.

- | Inspect for possible plugged catalytic converter. Refer to Restricted Exhaust .

• | Electromagnetic interference (EMI) circuit can cause an engine misfire condition. A scan tool can usually detect EMI by monitoring the engine RPM. A sudden increase in RPM parameter with little change in actual engine RPM change may indicate that EMI is present. If a problem exists, inspect for high voltage components near the ignition control circuits.