To reset the ECU:
Unplug the negetive battery terminal and step on the brake pedal for 5+ seconds. I think you will lose all preset radio stations and the trip distance meter.
What Resetting the ECU does:
There has been a lot of discussion on what resetting the ECU does. AFAIK, over time, depending on the type of fuel and how knock free your car is, the Ignition Advance Multiplier will either increase or decrease in 1/8 degree incriments from 1 to 16. Resetting the ECU will bring this number to 8. Depending on knock the multiplier will increase or decrease. When a new power modification is added and the ECU is reset, I believe the only change is with the Ignition Advance Multiplier going to 8. If this information is correct (someone please correct me if I am wrong) that would mean the only way you would notice a difference in power is if your IAM was low due to bad gas causing knock. Otherwise, under normal or hard driving conditions with good gas and no knock the multiplier should be fairly high and resetting the ECU will just bring it down to 8 and the ECU will have to 'relearn' and with good gas/no knock the IAM should go back up again. If I'm incorrect/misleading about anything please say something.

For more information on the Ignition Advance Multiplier, resetting the ECU, and a learning trick to bring the Multiplier up to 16 within seconds visit this link: https://www.i-club.com/forums/showth...u+ecu+learning

 

Out of all that bologne the only fact I know is that the WRX ECU learns and adjusts how the person drives. Resetting it after some performance mods wouldn't hurt at all.

 

Yeah, thats basically what awns729 is saying. He uses more precise words though.

 

your going to lose alot of gas...i know i did..and get boost in funny spurts...Also if your a better driver now then you were then you may get a different car feel. I know i have...

 

Well doesn't the gas in cali suck? That may be the reason for the complication.

 

My fuel mileage went down after I reset mine. But it slowly climbs back to where it was as it re-learns everything.

And it really smoothed out the powerband for me.

 

AFAIK, that would mean that you had knock and the ECU pulled timing at certain RPM to supress it. When you reset your ECU you had better gas and no knock for a long enough time (hopefully still have a constant supply of good gas, which would also mean no knock) and the ECU advanced the multiplier and now your car is knock free and happy!

 

Why would I have been getting knock? It's never seen anything under 91 octane, and the only mod I have is a cat-back.

<---- confused

 

Be a little more specific and maybe you can get a better answer

Maybe you reset it improperly, did you try it more than one time?

 

Well I don't understand why else the powerband would be smoother. Anyone have a good reason besides the knock thing I was talking about? Maybe someone else filled it with 89? I really don't know.

 

The smoothness could have all been in my head. Maybe I just wanted it to do more than it really did, so I thought it made it smoother. Maybe I'm just crazy (it wouldn't be the first time for that explanation ). Who knows.

Or maybe my wife filled it with a lower grade on accident when she had it...That's a definite possibility too.


I didn't try it more than once. Everything reset itself (trip meter, radio stations), so I just assumed that I did it right...

 

it's good and bad. if your ECU has adjusted to knock in certain areas of your powerband, resetting the ECU will cause your car to knock while it re-adjusts.

 

Well the only reason there should be knock is because of bad gas. ANd if you're regularly using bad gas (-91) then your engine will not live long. Otherwise if it was only once or twice and from then on 91+ has been use the ECU will advance the multiplier and you will notice slightly more power

 

Cool. Thanks guys!