Engine Controls - Tests W/O Codes: Introduction

Before diagnosing symptoms or intermittent faults, perform the basic steps in the BASIC TESTING article and also perform the self-diagnostic procedures in the TESTS W/CODES article. Use this article to diagnose driveability problems that exist when a hard fault code is not present or when 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.

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

NOTE: For specific component testing procedures, refer to the SYSTEM/COMPONENT TESTS article. For engine performance related specifications, see the ADJUSTMENTS article or the SPECIFICATIONS article.