For 1990-2009 cars

### Important Preliminary Checks Before Starting

Perform the Powertrain On Board Diagnostic (OBD) System Check and verify that all of the following are true before using the Symptom tables:

• | The PCM and the MIL are operating correctly.

• | Check that there are no DTCs stored.

• | Scan tool data is within normal operating range.

• | Verify the customer complaint and locate the correct symptom in the table of contents. Check the items indicated under that symptom.

Check for any of the following conditions:

• | Inspect all PCM grounds for secure and clean connections that are in the proper location.

• | Check all vacuum hoses for splits, kinks, and proper connections, as shown on the Vehicle Emission Control Information label. Check the vacuum hoses thoroughly for any type of leak or restriction.

• | Mass air flow (MAF) sensor installation is correct.

• | Inspect the air inlet ducts for collapsed or restricted sections.

• | Air leaks at throttle body mounting area, MAF sensor, and intake manifold sealing surfaces.

• | Inspect the ignition system secondary wires for cracking, hardening, carbon tracking, and the proper routing to each cylinder.

• | Inspect the wiring harness for proper connections and damage.

For more symptom base diagnostics refer to the following tables:

• | Hard Start

• | Surges/Chuggles

• | Lack of Power, Sluggishness, or Sponginess

• | Detonation/Spark Knock

• | Hesitation, Sag, Stumble

• | Cuts Out, Misses

• | Poor Fuel Economy

• | Rough, Unstable, or Incorrect Idle and Stalling

• | Dieseling, Run-On

• | Backfire

• | Restricted Exhaust System Check