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Engine Control System Tests W/O Codes: Introduction

Before using this article, perform basic diagnostic procedures in BASIC TESTING article and self-diagnostics in TESTS W/CODES 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.

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 an intermittent trouble code was present, but no problem was found during self-diagnostic testing.