Engine Controls - Tests W/O Codes: Introduction

Before diagnosing symptoms or intermittent faults, perform steps in BASIC TESTING and TESTS W/CODES article in the ENGINE PERFORMANCE Section. Use this section to diagnose driveability problems that exist when a hard fault code is not present.

NOTE: Some driveability problems may have been corrected by manufacturer with a revised computer calibration chip or computer control unit. Check with manufacturer for latest chip or computer application.

Symptom checks are intended to direct the technician to malfunctioning component(s) so that further diagnosis may be performed. A "symptom" should lead to further testing of specific components or systems, or verification of adjustment specifications.

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 a soft (intermittent) trouble code was present, but no problem was found during self-diagnostic testing.

NOTE: For specific testing procedures, see I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section. For verifying specifications, SPECIFICATIONS or ADJUSTMENTS article in the ENGINE PERFORMANCE Section.