For 1990-2009 cars

### Important Preliminary Checks Before Starting

Before using the Symptom tables:

• | Perform Powertrain On Board Diagnostic (OBD) System Check and verify all of the following items :

- | The powertrain control module (PCM) and malfunction indicator lamp (MIL) 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.

• | Perform the Visual/Physical Check.

Locate the correct symptom in the list at the end of this section. Follow the procedures in the appropriate diagnostic table. If the problem cannot be duplicated, also refer to Intermittent Conditions .

### Visual/Physical Check

Notice: Use the connector test adapter kit J 35616-A for any test that requires probing the following items:

• | The PCM harness connectors

• | The electrical center fuse/relay cavities

• | The component terminals

• | The component harness connector

Using this kit will prevent damage caused by the improper probing of connector terminals.

Several of the symptom procedures call for a careful visual/physical inspection. This can lead to correcting a problem without further tests and can save valuable time. This inspection should include the following areas:

• | Inspect the PCM grounds for being clean, tight, and in their proper location. Refer to The PCM grounds, refer to Power Distribution Schematics , and Ground Distribution Schematics in Wiring Systems.

• | Inspect vacuum hoses for splits, kinks, and proper connections, as shown on Vehicle Emission Control Information label. Inspect thoroughly for any type of leak or restriction. Refer to Emission Hose Routing Diagram .

• | Inspect the air intake ducts for being collapsed, damaged areas, looseness, improper installation, or leaking especially between the MAF sensor and the throttle body.

• | Inspect for air leaks at throttle body mounting area, mass air flow (MAF) sensor and intake manifold sealing surfaces.

• | Inspect the wiring harness for faulty connections, pinches, cuts or other damage.

• | Inspect for loose, damaged or missing sensors/components.

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

• | Poor Fuel Fill Quality

• | Rough, Unstable, or Incorrect Idle and Stalling

• | Dieseling, Run-On

• | Backfire

• | Restricted Exhaust System Check