For 1990-2009 cars

Checks | Action
--- | ---
DEFINITION: The fuel ignites in the intake manifold, or in the exhaust system, making a loud popping noise.
Preliminary Check |

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

• | Refer to Symptoms .

Ignition System Checks |

• | Check for adequate ignition coil voltage with a J 26792 spark tester or equivalent.

• | Check the spark plugs for any of the following conditions:

- | Any wet plugs

- | A terminal screw that is bent or loose

- | A ceramic insulator that has cracks, carbon tracking, or deposits

- | A tip insulator that has cracks, carbon tracking, deposits, or is loose

- | A center electrode that is loose

- | An incorrect spark plug gap that is too large or too small

• | Check for the correct ignition timing. Refer to Ignition Timing Adjustment .

• | Check for crossfiring between cylinders. Check for the correct routing of the ignition coil electrical connectors.

Engine Mechanical Checks |

• | Check for any of the following engine mechanical problems:

- | An incorrect valve lash

- | Any broken or weak valve springs

- | A low compression

- | Any sticking or leaking valves

- | An incorrect valve timing

- | An incorrect or worn camshaft

• | Refer to Engine Compression Test in Engine Mechanical.

• | Check the intake and exhaust system for casting flash or other restrictions.

Additional Checks |

• | Check for the proper fuel pressure. Refer to Fuel System Diagnosis .

• | Verify the PCM grounds are clean, tight, and in the proper locations. Refer to

#### Power and Ground

Engine Controls Components
MIL and DLC
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
G100, G101 and G102
H/L, HTR, IG and LAMP Fuses
HAZ, D/L, TAIL, STOP and DOME Fuses
BATT, ABS, FI and ACC Fuses
.

• | Check the Service Bulletins for any updates or information.