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Very high fuel trims!!

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91TSI505

20+ Year Contributor
256
0
Jan 10, 2003
Albuquerque, New_Mexico
Started logging today and i cant get my fuel trims lower than 132.No matter how much i richen it i can't get them any lower.Does the GM MAS have something to do with it?I am tuning with a translator and my mods are listed,Thanks in advance:thumb:
 
How long are you giving it to update? It will take a 91 several DAYS to update that much.

How does your 02 trim look?

Have you tried setting the dials close to where it would be 100%, then reset the ecu and saw how it updated after that?
 
So you mean setting the base setting dial @ -20% for the 550's,leave everything else where they are and reset the ECU?as soon as i change my idle setting the low trim goes up within seconds.And it seems like its stuck at 132,i can't get anything lower than that,Kinda boggled here,Thanks for your help

P.S. O2 trims were ~100 at idle and ~140-170 cruise.
 
The 02 trims will give you just as much of an idea as the fuel trims, but the scale is different. The upside is they update much faster.

What you need to do is set the idle, mid and wot at 0. Then take the car out and drive at a constant speed ~50mph (use a not so busy highway) and set the BASE to get the high trim where it should be. Drive it for a few days to let the trims settle, then begin to tune using the other 3 knobs.

The numbers given in the guide are just that, a guide. Let the car tell you what it wants. If you have to set the base -10 or -35, don't worry about it.

Also, if the trim is 132, remember, you need to ADD fuel. >100 means the ecu is having to add more to get the mix. stoich.

Good luck, and have fun with it.
 
That makes alot of sense:thumb: I will do that over the next few days and let you know how everything works out,Thanks for taking the time to help me!
 
That's alright. It seems there is still some confusion about how to tune iwth the maft.

I guess you get that with any new product.
 
Faulty coolant temp sensor could cause this as well. .:D
 
Originally posted by Robby Camero
Faulty coolant temp sensor could cause this as well. .:D
Explain.
 
All I really know is that if your coolant temp sensor for the ecu is malfuntioning, your trims wont adjust and will go full lean. It happened to both my talons so this is just from personal experiance but I am not the only one. There was quite a bit of disscussion on it on the ca.dsm.org board.
 
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