For 1990-2009 cars

Inspection/Test | Actions
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DEFINITION: Fuel ignites in the intake manifold, or in the exhaust system, making loud popping noise.
Preliminary |

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

• | Refer to Intermittent Conditions .

• | Search for bulletins.

Sensor/System |

• | Inspect for the following intermittent ignition system conditions:

- | Monitor the 24X Crankshaft Position and Camshaft Position Sensors on scan tool. If both are not responding, test the sensor feed circuit. Both sensors use a separate feed circuit but are internally connected to power. Test all 24X and CMP sensor circuits for intermittents. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

- | Monitor the 3X parameter on the scan tool. If the 3X is not responding, inspect the 7X CKP Sensor and circuits for intermittents. Inspect the IC circuit, Bypass circuit, 3X Reference High Circuit, and the 3X Reference Low circuit for intermittents. If these circuits become open, or shorted may not set a DTC immediately, but are capable of causing driveability complaints. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

• | Inspect the mass air flow (MAF) sensor. Ensure that the MAF sensor honeycomb is not damaged.

Fuel System |

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

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

• | Ensure each injector harness is connected to the correct injector/cylinder.

Ignition System |

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

1. | Attach the J 26792 spark tester to engine ground.

2. | Connect the spark plug end of the spark plug wire to the J 26792 spark tester; leave the other end of the spark plug wire connected to the coil being tested.

3. | Connect the spark plug end of the companion spark plug wire to ground.

The companion spark plug wire is the wire attached to the corresponding coil tower.

4. | Crank the engine while observing the J 26792 spark tester; a spark should be observed.

5. | Repeat the above steps for each coil.

• | If spark is not present at the coils, inspect for the following conditions:

- | Coils--Cracks, carbon tracking/arcing, or a resistance value outside the specified range.

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

- | 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 Wire Resistance
600ohms per foot (1 968ohms per meter).

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

- | Defective ignition module.

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

• | Remove spark plugs and inspect 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 |

• | Inspect engine mechanical components for the following conditions:

- | Test compression--Refer to Engine Compression Test in Engine Mechanical.

- | Sticking or leaking valves

- | Worn camshaft lobes

- | Valve timing

- | Bent push rods

- | Worn rocker arms

- | Broken valve springs

- | Excessive oil in combustion chamber-Leaking valve seals

- | Low cylinder compression

• | Inspect for the following incorrect basic engine parts:

- | Camshaft

- | Cylinder heads

- | Pistons, etc.

• | For more diagnostic aids refer to Base Engine Misfire Diagnosis in Engine Mechanical.

Additional |

• | Inspect the intake and exhaust manifolds for casting flash.

• | Test TCC operation. Refer to Torque Converter Diagnosis in Automatic Transaxle.

• | Inspect the exhaust system for possible restrictions in the following areas:

- | The exhaust system for damaged or collapsed pipes

- | The mufflers for heat distress or possible internal failure

- | The catalytic converter for possible plugged condition--Refer to Restricted Exhaust System Check and Exhaust Leakage - Not OBD II in Engine Exhaust.