Engine Control System Tests W/O Codes: Introduction
Before diagnosing symptoms or intermittent faults, perform steps in appropriate BASIC TESTING article and appropriate TESTS W/CODES article. Use this article to diagnose driveability problems existing when a Diagnostic Trouble Code (DTC) is not present.
NOTE:
Some driveability problems may have been corrected by manufacturer with a revised Engine Control Module (ECM). Check with manufacturer for latest ECM application.
Symptom checks can direct the technician to malfunctioning component(s) for further diagnosis. A symptom should lead to a specific component, system test or adjustment.
Use intermittent test procedures to locate driveability problems that DO NOT occur when the vehicle is being tested. These test procedures should also be used if an intermittent trouble code was present, but no problem was found during self-diagnostic testing.