For 1990-2009 cars

### Important Preliminary Checks

#### Before Starting

Before using this section you should have performed the Diagnostic System Check-Engine Controls and determined that the following items are OK:

• | The PCM and MIL, check engine, are operating correctly.

• | There are no DTCs stored.

• | Scan tool data is within normal operating range, refer to Scan Tool Data List .

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

### Visual/Physical Check

Several of the symptom procedures call for a careful visual/physical check. The importance of this step cannot be stressed strongly enough. This step can lead to correcting a problem without further checks and can save valuable time. This check should include:

• | PCM grounds for the following conditions:

- | Clean connection

- | Tight connection

- | Proper location

• | Vacuum hoses for the following conditions:

- | Splits

- | Kinks

- | Proper connections as shown on Vehicle Emission Control Information label

- | Leaks

- | Restrictions

• | Air leaks at the following components:

- | Throttle body mounting

- | Intake manifold sealing surfaces

• | Wiring for the following conditions:

- | Proper locations

- | Pinches

- | Cuts

• | Use the following tables when diagnosing a symptom complaint:

- | 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

- | Malfunction Indicator Lamp (MIL) Inoperative

- | Malfunction Indicator Lamp (MIL) Always On