fuel trims high, what gives
08-16-2007, 01:05 AM
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fuel trims high, what gives
Had thunder do some logging for me between my mail order tune and my stock PCM and the major concern is my fuel trims are getting up there. With the mail order tune I believe the highest it got was 19 maybe at WOT and with the Stocker we hit 26+ if I remember correctly. I have checked for air leaks, most vacuum lines that I could find and everything seems good. Other than that everything else looked fairly normal. Hopefully Thunder will chime in since he can read the graphs a lot better than I but wtf is going on with these fuel trims? Also anyone else who is EFIlive guru I will be more than happy to send over the logging we did.
08-16-2007, 01:09 PM
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as for WOT hell I dont know, I dont know how to really read the graphs, thunder went over it with me some but didnt teach me a course on the stuff ya know. lol
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08-17-2007, 03:20 PM
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Posative fuel trims (lean) at part throttle are added on top of the open loop fueling when you go to WOT. It is the computers way of attempting to save a lean running engine when you go into WOT. Whatever posative fueling you have at the time it goes into open loop locks in until you go back to closed loop.
If you have no vacuum or exhaust leaks, then its the tune. But if you have LTFTs that high at idle, you likely have a leak somewhere. Spray it down with carb cleaner while its running, and you'll find it if its vacuum. Exhaust should be obvious.
If you have no vacuum or exhaust leaks, then its the tune. But if you have LTFTs that high at idle, you likely have a leak somewhere. Spray it down with carb cleaner while its running, and you'll find it if its vacuum. Exhaust should be obvious.