Engine Controls - Tests W/O Codes: Introduction

Before diagnosing symptoms or intermittent faults using procedures in this article, perform checks in BASIC TESTING article and diagnostic tests in the SELF-DIAGNOSTICS - 4.0L article. Use this article to diagnose driveability problems existing when a hard fault code 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 an adjustment.

Use intermittent test procedures to locate driveability problems that DO NOT occur when 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. See INTERMITTENT PROBLEM DIAGNOSIS under INTERMITTENTS.

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