Engine Controls - Tests W/O Codes - Gasoline: Introduction

WARNING: When battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN article in the GENERAL INFORMATION Section before disconnecting battery.

Before diagnosing symptoms or intermittent faults, perform steps in appropriate BASIC TESTING and TESTS W/CODES (if applicable) articles in the ENGINE PERFORMANCE Section. Use this article to diagnose driveability problems that exist when a hard fault code is not present.

NOTE: Some driveability problems may have been corrected by manufacturer with a revised computer calibration chip or control unit. Check with manufacturer for latest chip or control unit 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 specification.

Use intermittent test procedures to locate driveability problems that do not occur while the vehicle is tested. These problems may noticeably affect driveability or cause CHECK ENGINE light to glow. Also use these test procedures if a soft (intermittent) trouble code was present but no problem is found during self-diagnostic testing.

NOTE: For specific testing procedures, see appropriate I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section. For specifications, see appropriate ADJUSTMENTS or SPECIFICATIONS article in the ENGINE PERFORMANCE Section.