PCM "re-learn"?

[Bruce Mitchell]

Hello, all:

I just completed routine battery maintenance on my '99 5.4L EB AWD/4WD.

Naturally, battery was disconnected. Is there anything special I need to do or will the vehicle computer do its own "re-learn"?

Thanks and Happy Holidays!

 

[deweysmith]

It should be in your owner's manual. Here's mine:

1. With the vehicle at a complete stop, set the parking brake.
2. Put the gearshift in P (Park), turn off all accessories and start the engine.
   
3. Run the engine until it reaches normal operating temperature.
   
4. Allow the engine to idle for at least one minute.
   
5. Turn the A/C on and allow the engine to idle for at least one minute.
   
6. With your foot on the brake pedal and with the A/C on, put the vehicle in D (Drive) and allow the engine to idle for at least one minute.
7. Drive the vehicle to complete the relearning process.

• The vehicle may need to be driven 10 miles (16 km) or more to relearn the idle and fuel trim strategy.
• If you do not allow the engine to relearn its idle trim, the idle quality of your vehicle may be adversely affected until the idle trim is eventually relearned.

This isn't crucial, it will relearn on its own as you drive, but it may stumble at stop lights until it has learned. This is also separate from the transmission re-learn, you may notice some harsh shifts for the first little bit.