For 1990-2009 cars

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

• | Refer to the Powertrain On Board Diagnostic (OBD) System Check .

• | Refer to Important Preliminary Checks .

• | Refer to Visual/Physical Checks .

• | Search for bulletins.

Sensor/System |

• | Check for the following intermittent ignition system conditions:

- | Intermittent CKP Sync or CKP 18X Signal.

- | Intermittent ignition feed circuit or sensor ground circuit to the crankshaft position sensor or the camshaft position sensor.

- | Intermittent 3X reference signal.

- | Intermittent camshaft position signal

• | Check the Mass Air Flow sensor conditions. Ensure that the MAF Sensor honeycomb is not damaged.

Fuel System |

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

• | Check for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Test .

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

Ignition System |

• | Check for proper ignition voltage output using the following steps:

- | Clip the spark tester J 26792 to engine ground.

- | Connect one end of a spark plug wire to the spark tester; leave the other end of the spark plug wire to the coil being tested.

- | Connect one end of another spark plug wire to the other coil tower; connect the other end of the spark plug wire to ground.

- | Crank the engine while observing the spark tester; a crisp blue spark should be observed.

- | Repeat the above steps for each coil.

• | If adequate spark is not present at the coil(s), check for the following conditions:

- | Coil(s) - Cracks, carbon tracking/arcing, or a resistance value outside the specified range.

Coil Resistance
5000 - 8000 ohms (5K - 8K ohms)

- | Spark Plug wires - Signs of arcing/cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside the specified range.

Spark Plug Resistance
Less than 10000 ohms (10K ohms)

| Important: Spraying the secondary ignition wires with a light mist of water may help locate an intermittent problem. Ignition components will arc to ground when a secondary component is faulty.

- | Defective module.

- | Ignition System Wiring - Loose ignition module feed or ground connection, or damaged system wiring.

• | Remove spark plugs and check for the following conditions:

- | Fouled plugs

- | Cracks

- | Wear

- | Improper gap

- | Burned or damaged electrodes

- | Improper heat range or reach

• | If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.

Engine Mechanical |

• | Check engine mechanical:

- | Check compression.

- | Sticking or leaking valves.

- | Worn camshaft lobe(s).

- | Valve timing.

- | Bent push rods.

- | Worn rocker arms.

- | Broken valve springs.

- | Excessive oil in combustion chamber-Leaking valve seals.

- | Low cylinder compression.

• | For incorrect basic engine parts. Inspect the following:

- | Camshaft

- | Cylinder heads

- | Pistons, etc.

• | Refer to Engine Mechanical for diagnosis procedures.

Additional Checks |

• | Check Intake and exhaust manifold(s) for casting flash. Refer to Engine Mechanical .

• | Check TCC operation. Refer to Automatic Transmission Diagnosis .

• | Check the exhaust system for a possible restriction.

- | Inspect exhaust system for damaged or collapsed pipes.

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

- | For possible plugged Three-Way catalytic converter. Refer to Restricted Exhaust System Check and Exhaust System .