Engine Controls - Tests W/O Codes: Introduction

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

Before diagnosing symptoms or intermittent faults, perform steps in BASIC TESTING article and appropriate TESTS W/CODES article. Use this article to diagnose driveability problems existing when a hard fault code is not present.

Some driveability problems may have been corrected by manufacturer with a revised computer control unit. Check with manufacturer for latest computer application.

Symptom checks can direct the technician to malfunctioning components for further diagnosis. A symptom should lead to a specific component test, system test or an adjustment.

If no fault codes are present and driveability or customer complaints are present, perform functional test on Electronic Idle Speed (ELR), Exhaust Gas Recirculation (EGR) and Boost Pressure Control (P-2) systems. See FUNCTIONAL TEST under DIAGNOSTIC TESTS in TESTS W/CODES article.