Does anyone have any idea how long the ecu takes to re-establish its fuel map after pulling the room fuse? My battery went dead a couple of weeks ago, resetting my ecu. I drove through the rest of the tank (approx 3/4 full) and I got 20.5 MPG. I refueled and ran an autocross weekend and it drank at the rate of around 15 MPG. Needless to say, I've pulled it again to reset the map for my daily driving.

Previous to this, I was getting 19 to 21 MPG even doing autocross events. Any idea on how long it takes to settle in?

 

Bump

 

Drive it for <15 minutes and you're set.

 

there are LTFT(Long Term Fuel Trim) and STFT(Short Term Fuel Trim)

it takes couple of drive cycle to build the maps. and each drive cycle is NOT just turn your car on, go on a highway for 15 mins, come back and go to sleep.

it takes time.

 

Resetting the fuel trims would be a good thing when replacing the cat with a mid pipe, right? I'm not getting good mileage anymore once I swapped it out...

 

How would it be a good thing? Just asking

 

you dont have to reset it everytime u make some modifications, its just that its "faster" this way.

 

Thanks!

 

Thanks all. I had searched the topic here in the forums, but never could find a definitive answer. At least now I know that if I do an auto-X in the near future, it shouldn't screw the fuel trims TOO much. :D