For 1990-2009 cars

Checks | Action
--- | ---
DEFINITION: The fuel ignites in the intake manifold, or in the exhaust system, making a loud pop.
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 with an equivalent.

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

- | Wet plugs

- | A bent or loose terminal screw

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

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

- | A center electrode that is loose

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

- | Refer to Spark Plug Visual Diagnosis in Engine Electrical.

• | Check for crossfiring between spark plugs

Engine Mechanical Checks |

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

- | An incorrect valve lash

- | Broken valve springs or weak valve springs

- | Low compression

- | Sticking valves or leaking valves

- | Incorrect valve timing

- | An incorrect camshaft or a worn camshaft

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

Additional Checks |

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

• | Check the PCM grounds for being clean, tight, and in the correct locations. Refer to

#### Cell 21: Power and Ground

.

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