ECU Reset Guide for RX-8

This is the same walkthrough as featured in our other technical article “RX-8 Stalls when Battery is Disconnected” We have placed it here as its also the best way to reset the ECU anyway.

This is a brief guide to a possible solution for those that have problems with the car idling after your battery has been disconnected and the ECU reset.

Assuming that you have a healthy car with no other problems the below procedure should work for you.
Its best to do this when the engine it totally cold this will give the engine the best chance of not stalling

Many of us may not know that after you disconnect your battery from the car for some reason, this will lead to all your cars fuel trim setting and information the ECU has learned about your driving style to be lost. This will also wipe any fault codes on the PCM and reset your DSC.
Once you reconnect your battery you will need to go through several steps to reset things like the DSC.

DSC Reset procedure
1. Put the key in the ignition and turn in to position 1
You should notice that on your dash the “DCS OFF” sign is flashing and that your skiddy car sign (found in the center cluster just under the center of the needle) is illuminated.

2. Pump the brake pedal rapidly 20 times (in some cars members have reported that this will lead the Oil pressure gauge found in the left cluster to do a full sweep though this does not happen with all cars so do not be worried)
At this stage you should still have the skiddy sign illuminated and the “DSC OFF” still flashing.

3. Turn your key all the way to start the car (make sure your foot does not touch the throttle) If you have followed the above information and have done it with a cold engine then you still notice that the revs will rise to about 2000rpm this it totally normal.

4. Now leave the car to Idle and warm up naturally, you will see the revs slowly drop as the engine warms up, it should not be needed but if the engine sounds like its going to stall then give it a little throttle just to keep it above stalling (however this is why I say do it when the engine is cold) Allow the engine to run for at least 10 minutes at idle (though I normally give it a good 20 mins)
This step is important as at this stage the cars ECU is learning how to fuel and run the engine again so if you can resist touching the throttle then do.
If your “DSC OFF” light has gone off then skip this next step

5. If your “DSC OFF” light is still illuminated then your will need to turn your steering wheel one full lock to the Left then all the bay back to the Right, This should put out your “DSC OFF” light now return your steering wheel to the central position.

6. By now your engine should be nice and warm and safe to switch off with no risk of flooding, So to extinguish the skiddy sign you will now need to turn the engine off (turn the key all the way to the off position) and on the second restart you should find that your skiddy light is now out. (many people will restart the car straight after turning it off to extinguish the skiddy sign however if you find that your cars still not idling then follow the below procedure)

I have reset my ECU and DSC but my car still keeps stalling on idle?
If you have followed all the above steps and your engine still will not idle then your engines ECU may need longer to learn, In truth the engines ECU takes quite a while to finish learning sometimes up to 100miles + (most cases its a lot less) of driving can sort this out during this time you may find you need to keep the engine from stalling by blipping the throttle while your stationary.
If after your have given the car approx 100miles (it should learn before you hit 100) to learn how to fuel the car correctly so it does not stall at idle when warm then try the below procedure.

Idle stall prevention
1. Make sure your cars engine and Catalytic Converter (CAT) are completely cold ideally leave it overnight to cool right down.

2. Start your car in the usual manner (keep your foot off the throttle)
As your car was cold on start up this will mean that the car pumps extra fuel in and raises the revs (like in step 3 above) to warm the cars CAT up to operating temperature quickly.

3. Do not touch the throttle but leave the car to warm up naturally and once warm leave to idle for between 15-20 mins.

4. Once you have given it 15-20 mins shut the car off then restart.
Your idle problem should now be no more.

Happy Rotoring.

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