High EGTs on highway?? lean fuel trims

[92tsiMboostin]

my egt's get close to 1600 on the highway crusing between 70-80. the first few miles on the highway the temps are lower. is the egt gauge only for wide open throttle tuning... i never get above 1550 on wide open pulls. i have an equal length header with the egt bung in the collecter...not in the 1st runner. could that be a problem? my car was tuned with a wideband o2 on a dyno(286whp @ 16psi), the car ripped and showed 100% (1g) on my logger (mmcd) until i drove back to school down the turnpike for an hour or so. then my logger showed 126% high, 117% mid, 86% low (). i keep throwing more and more fuel at it with my safc. now the high and low throttle are way higher then when it was tuned and it didn't help. i changed the o2, have a new tps (install it when i go home). any ideas would be greatly appreciated. the car still pulls real hard, but the high fuel trims worry me. i didn't spend all that money on monitoring equipment not to pay attention to them. thanks in advance.

 

[overdoseheroin]

dont sweat it. as long as theyr enot crazy under wot then its fine. but id try and add fuel on your low throttle. my low throttle fuel curve it way higher than my high throttle. just watch the logger when ur sittin there at idle and add fuel or take it away until the trim is at about 100% then go from there. or just add fuel until they stay lower. crusing, mine are at about 1300-1400, but at wot, they tend to drop a littlwe bit but never go higher than 1400.

 

[92tsiMboostin]

any ideas why they would change after the dyno tune? i didn't pay 400 bucks to have to tune it myself anyway, know what i mean. the high and mids come down once i get to my destination, that is, once i drive around town for a couple of days. but as soon as i go back on the highway for a distance drive they skyrocket. i can't seem to find anyone on the forums with a similar situation. the only thing i could think of that would raise the fuel tirms is a lazy or dead o2 sensor. once i replaced that, the fuel trims where at 100% even though the settings where still the increase fuel settings i played with after the tune?! then once i drove back to school on the highway the trims went way up again! it's driving me nuts!! also... when i try to lauch or peg it in 1st gear in jumps then bogs down like its crazy rich or something, but it pulls hard in every other gear. the place that tuned my car couldn't figure this one out either.... thanks for the reply, if you or anyone else has any ideas i'd appreciate it.

 

[92tsiMboostin]

it seems like you should start your own thread...i was looking for some help on my car....doesn't look like you are able to help. thanks anyway

 

[mavisky]

it seems like you should start your own thread...i was looking for some help on my car....doesn't look like you are able to help. thanks anyway

A friend of mine had the exact same situation in his car, a 1990 awd. We could never get the thing to cooperate. Just like you described he could get it to work out one day, then the next it was way off again. He finally got sick of it, parted out the car and bought a 2g. We bugged him to try a new ecu, but we couldn't find another 1990 ecu around to try. In your case you could use any ecu from a 5 speed turbo from 1991-1994. It's probably worth a shot.

 

[92tsiMboostin]

i know it was rebuilt 4 years ago...if i can find one cheap i'll give it a try. i plan on buy a stand alone system when im finished with my new motor. thanks again.... anyone else have an idea

 

[92tsiMboostin]

what happend to the post when you where asking about your car???? or did you just email me. sorry... reading the post now i sound crazy... maybe i am! haha thanks again

 

[mavisky]

what happend to the post when you where asking about your car???? or did you just email me. sorry... reading the post now i sound crazy... maybe i am! haha thanks again

I thought your problem was closely linked to mine, after re-reading your original post I realized our issues were different. I deleted the post and then re-opened a new thread for mine.