Computer Relearn Procedures Acura MDX I

INTRODUCTION

Note. Before replacing any component that scan tool suggests are faulty. Ensure that all wiring connections and harness connectors are okay. Ensure that power and ground circuits are functioning properly. For circuit identification, see ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL for vehicle being tested.

BODY CONTROLS

Vehicles equipped with body, air conditioning, anti-lock brake or memory computers may require a computer relearn procedure after components are replaced, ECM/PCM is reset or the vehicle battery is disconnected. Vehicle computers memorize and store vehicle information and operation selections. When the vehicle battery is disconnected, vehicle computer memory may be lost, requiring relearning or resetting. Depending on the vehicle and how it is equipped, the following memories may exist

1. Seat position.
2. Tilt/telescoping steering wheel position.
3. Mirror position.
4. Radio presets and anti-theft code.
5. Clock.
6. Remote keyless entry custom features.
7. Door key lock entry custom features.
8. Power window or sunroof operation.

These do not affect vehicle operation. For systems that do not affect operation, see appropriate article for relearn procedures. Other computer relearn procedures are required for vehicle or system operation. These may include

1. Initial control unit programming.
2. Traction control yaw sensor initializing.
3. Multiplex communication.
4. Anti-theft system or engine immobilizer system passwords.

ENGINE CONTROLS

Vehicles equipped with powertrain control modules may require a computer relearn procedure after the vehicle battery is disconnected. Vehicle computers memorize and store vehicle operation patterns for optimum driveability and performance. When the vehicle battery is disconnected, this memory is lost, which may result in a driveability problem. Depending on the vehicle and how it is equipped, the following driveability problems may exist

1. Rough or unstable idle.
2. Hesitation or stumble.
3. Rich or lean running.
4. Poor fuel mileage.
5. Harsh or poor transmission/transaxle shift quality.

Default data is used until NEW data from each key start is stored. As the computer restores its memory from each new key start, driveability is restored.

Driveability problems may occur during the computer relearn stage. To accelerate computer relearn process after battery removal and installation, specified computer relearn procedures should be performed. See appropriate procedures for specified manufacturer.

IDLE LEARN PROCEDURE

All Acura models with programmed fuel injection (PGM-FI) have the ability to learn and adjust the engine idle speed to optimize engine idle characteristics. The idle learn procedure should be done whenever you do any of these actions

1. Reset, replace, unplug, or reprogram the ECM/ PCM.
2. Disconnect or replace the battery.
3. Do engine work that requires removal and replacement of the intake manifold or the throttle body.

To allow the ECM/PCM adaptive idle speed system to learn and adjust the engine idle speed, follow this procedure

1. Make sure all electrical items (A/C, audio unit, defogger, lights, etc.) are turned off, then start the engine.
2. Let the engine reach its normal operating temperature (the cooling fans cycle twice; the coolant temperature is about 194° F).
3. Let the engine idle for at least 5 minutes with the throttle fully closed and with all electrical items turned off.
4. If the cooling fans cycle on while doing an adaptive idle learn, add the time the cooling fans are on to the 5 minute adaptive idle learn time.