How to reset ECU?

[Patrick F. Clarin]

I just put an AEM Cold Air Intake in my 02' WRX, every where I read said to
reset your ECU when you're done. How do I do that?

 

[Sam Li]

Disconnect the battery's negative cable for about an hour will clear all the
air/fuel ratio parameter the ECU accumulated.

 

[Patrick F. Clarin]

And this is a good thing to do after a modification right?

 

[Sam Li]

I don't know about that. I know this 'cause I did it for resetting my check
engine light, and as a side effect it also cleared the air/fuel ratio
parameter.

 

[Patrick Fisher]

And this is a good thing to do after a modification right?

It can't hurt. It forces the ECU to immediately re-learn the fuel trims,
rather than adapting slowly over time.

The general concensus is that CAIs on a WRX are not really worth it, though.
They both increase the likelihood of ingesting water from a puddle (minor
risk), and lean out the intake mix by throwing off the calibration of the
factory MAF sensor (typically a minor issue if that's your only mod). They
may make a small amount of power by leaning it out, though.

 

[CompUser]

Disconnect the battery's negative cable for about an hour will clear all the
air/fuel ratio parameter the ECU accumulated.

Just disconnect the negative batt cable and press
the brake pedal down for ten seconds. If your
clock and radio stations are cleared, you're
done.

 

[John]

And this is a good thing to do after a modification right?

Always.
And when you first start the car after reconnecting the battery/fuse/fusable
link, put the key in the "on" position for a few seconds without touching
the gas. Then start and let the ECU re-learn the settings with the new mod.
You can spend that time resetting your clock and radio presets.

 

[WRXtreme]

It can't hurt. It forces the ECU to immediately re-learn the fuel trims,
rather than adapting slowly over time.

That is true, one of the tuners on www.NASIOC.com has a procedure that they
use for resetting the ECU to get maximum power. Do a search there and you
should find it.

The general concensus is that CAIs on a WRX are not really worth it, though.
They both increase the likelihood of ingesting water from a puddle (minor
risk), and lean out the intake mix by throwing off the calibration of the
factory MAF sensor (typically a minor issue if that's your only mod). They
may make a small amount of power by leaning it out, though.

Only 3 manufacturers (APS, Perrin & TurboXS) actually make a CAI that they
guarantee won't interfere w/ the MAF. The only one of the 3 that I've found
to be exceptionally made is the APS unit. Perrin is probably my second fave
of them w/ TXS coming in 3rd, although none of them are "bad" CAI's.

 

[Patrick Fisher]

Only 3 manufacturers (APS, Perrin & TurboXS) actually make a CAI that they
guarantee won't interfere w/ the MAF. The only one of the 3 that I've found
to be exceptionally made is the APS unit. Perrin is probably my second fave
of them w/ TXS coming in 3rd, although none of them are "bad" CAI's.

TXS's isn't a CAI, though - it's a short-ram intake (just a pipe, same
diameter as factory, and a K&N cone filter). I have one, and love the
sound. No complaints with quality. Have heard good things about APS and
Perrin as well, though.