Engine Controls - Tests W/O Codes: Introduction

Before diagnosing symptoms or intermittent faults, perform BASIC DIAGNOSTIC PROCEDURES in the BASIC TESTING and DIAGNOSTIC TESTS in the TESTS W/CODES articles in this section. 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 manufacturer 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 an 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 testing procedures, see appropriate SYSTEM/COMPONENT TESTS : Refer to the following list.

For specifications, refer to the appropriate ADJUSTMENTS or SPECIFICATIONS article.