For 1990-2009 cars

### Important Preliminary Checks Before Starting

Before using this section, perform Powertrain On Board Diagnostic (OBD) System Check and verify all of the following items are true:

• | The PCM and MIL are operating correctly.

• | There are no DTCs stored.

• | Ensure that the engine coolant temperature is not above 128°C (262°F). This condition will cause the PCM to operate in Coolant Hot Mode. While in Coolant Hot Mode, the PCM will turn fuel OFF to three cylinders to keep engine temperatures from reaching damaging levels. Coolant Hot Mode will be perceived as a lack of power, miss, or rough idle. If the vehicle is operating in Coolant Hot Mode, refer to Engine Overheating .

• | Scan tool data is within normal operating range. Refer to Engine Scan Tool Data List .

• | Verify the customer complaint and locate the applicable symptoms. Perform the procedure included in the symptom diagnostic table.

### Visual/Physical Checks

Several of the symptom procedures call for a visual/physical inspection. A careful visual/physical inspection can aid in correcting a problem without further checks and can save valuable time. A visual/physical inspection should include the following items:

• | PCM grounds for being loose, corroded, or in an improper location.

• | Vacuum hoses for splits, kinks, and improper connections. The proper connections are shown on the Vehicle Emission Control Information label. Check the vacuum hoses for any type of leak or restriction. Refer to Emission Hose Routing Diagram .

• | Inspect the air intake ducts for collapsed or damaged areas.

• | Check for air leaks at throttle body mounting area, Mass Air Flow (MAF) sensor, and intake manifold sealing surfaces.

• | Inspect the ignition wires for cracking, hardness, proper routing and carbon tracking.

• | Inspect the wiring for improper connections, pinches and cuts.

The following Symptom tables are located in this section:

• | Intermittent Conditions

• | 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