Engine Controls - Trouble Shooting - No Codes: Introduction
Before diagnosing symptoms or intermittent faults, perform steps in BASIC DIAGNOSTIC PROCEDURES article and appropriate SELF-DIAGNOSTICS article. Use this article to diagnose driveability problems existing when a hard fault code is not present or vehicle is not equipped with a self-diagnostic system.
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.
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 appropriate SYSTEM & COMPONENT TESTING article. For specifications, see
ON-VEHICLE ADJUSTMENTS or
SERVICE & ADJUSTMENT SPECIFICATIONS article.