Engine Cold

Perform the following in order:

• Check fuel pressure. See BASIC TESTING article.
• Check fuel injector operation. See SYSTEM/COMPONENT TESTS article.
• Check injector operation. See SYSTEM/COMPONENT TESTS article.
• Check ignition spark and spark plugs.
• Inspect harness connector for damaged pins or poor connection.
• Check ECM power supply and ground.
• Replace ECM with known good unit.

Engine At Operating Temperature - Perform the following in order:

• Check fuel injectors for leakage. See SYSTEM/COMPONENT TESTS article.
• Check fuel injector operation. See SYSTEM/COMPONENT TESTS article.
• Check ignition spark and spark plugs.
• Check EGR valve for stuck open condition.
• Inspect ECM harness connector for damaged pins or poor connection.
• Check ECM power supply and ground.
• Replace ECM with known good unit.