System Diagnosis: Operation

A leaking fuel injector can cause excessive pre-ignition knock, poor engine performance, excessive black smoke in the exhaust, poor fuel economy and rough engine idle. If the fuel injector needle valve does not operate properly, the engine may misfire and produce low power.

The Fuel Injection System is controlled by the Powertrain Control Module (PCM). If the PCM senses a fault in a monitored fuel system circuit, the PCM will store a Diagnostic Trouble Code (DTC), which can retrieved with a Scan Tool. The On-Board Diagnostic functions of the PCM must be used to test the system when diagnosing mechanical or electrical problems with the Fuel Injection System. In addition to diagnosing electrical faults, the Scan Tool has the following functions to test the mechanical operation of the injectors:

• Compression Test
• Fuel Correction Test
• Balance Test
• Kill Test

For Fuel System DTC information. Refer to POWERTRAIN CONTROL MODULE (PCM) - ELECTRICAL DIAGNOSTICS - 62TE AUTOMATIC TRANSMISSION .