For 1990-2009 cars

#### Backfire

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

• | Refer to Diagnostic System Check - Engine Controls .

• | Refer to Symptoms - Engine Controls .

Ignition System Checks |

• | Check for the proper ignition coil output voltage with a J 26792 Spark Tester or equivalent.

• | Inspect the spark plugs for correct operation and good ignition system performance. Refer to Spark Plug Inspection .

• | Inspect the ignition coil boots for damage.

Engine Mechanical Checks |

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

- | 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 Mechanical.

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