Resetting the ECU
Resetting the ECU is recommended to do after you do any modifications to your engine. The process is very simple and it can make a difference in the way your engine runs. This process should be done with the engine totally cold (ie. right after you've spent some time adding something nice to the engine bay of your car).
Step One: Cutting the power
Either take out the ECU fuse or remove the negative (-) terminal of your battery. The ECU fuse, in most cases, is located in the engine bayfuse box, but there may be some cars wheret this does not apply. If you can't find the fuse, there's always the battery.
Step Two: Taking a break
After all that work removing the fuse or disconnecting the negative terminal of the battery, take a 15 minute break. Seriously, wait 15 minutes.
Step Three: Reconnecting and starting
After the well needed break, reconnect the battery or fuse. Then go and start the car but DO NOT touch the gas. Let the car idle until it's completely warmed up (when the cooling fan has gone on at least twice). Then turn the car off and do what you want with it. Go for a drive, whatever.
