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Old 05-23-2006, 10:11 AM   #1
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Default Quick Fuel trim Question

At idle my Long Term, fully warmed up is 125
At WOT it hits 150 and doesnt go any higher or lower..
this normal?
not even 100% what it all means..
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Old 05-23-2006, 10:29 AM   #2
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Matt, Here'* a pretty good article that exlplains fuel trim in understandable terms. Worth a read...

Ross-Tech, Fuel Trim Explained

Something seems pretty fishy with the long term trim values you are reporting. As the article states and from my personal experience scanning mine, your trim should center around zero. Huge positive trims indicate something wrong, IMO (Note that I could be wrong) and could indicate a severely lean situation or maybe even a bad MAF.

Please keep in mind that I have no personal experience with trim levels and their possible connotations and am only interpreting, based on what I've read.
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Old 05-23-2006, 11:08 AM   #3
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Here'* another article on fuel trims with a bit of different info:

Fuel Trims

BTW, thanks! I'm learning some stuff here. :thumbsup:
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Old 05-23-2006, 11:39 AM   #4
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I think the PCM has learned you were rich at idle and REALLY lean at WOT. But I might have that backwards.
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Old 05-23-2006, 11:49 AM   #5
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What are you gauging it with, I also learned you should be around 0 - plus or minus a few.Maybe you are gauging it differently.
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Old 05-23-2006, 11:51 AM   #6
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There is trim, and there is integrator. Trim should be around 128, integrator should be around 0, if I remember right.
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Old 05-23-2006, 02:37 PM   #7
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Interestingly, there'* something to be learned about fuel trim by reading this thread:

http://www.bonnevilleclub.com/forum/...asc&highlight=

If you get past the argument/discussion at hand in that thread, it indicates that your long term trims are way too high at WOT and that you're probably running too lean there. Above where your pCM can correct for it. Are you getting KR?

As I know that you have done a bunch of work on your engine, diagnosis will depend a lot on your knowledge and input.

Again, realize that I have no firsthand experience with this, but I can read and apply. More specific input will have to come from the few here who are personally experienced.
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Old 05-23-2006, 02:54 PM   #8
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I pull 6 degrees of KR at WOT with my smaller pulley on the SC, i pull 0 degrees of Kr with the stock pulley.
It does NOT run that nicely top end wth the small pulley, infact, my exhaust manifolds will turn red at WOT.
indicating some kind of lean condition, regardless of what the 02 is telling me.
Under even say half throttle it pulls 0 kr, however you can tell it has to work its way through the 3000-4000 rpm band like it does it in stages.
this is Long Term trim as well.
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Old 05-23-2006, 03:43 PM   #9
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Do the manifolds turn the same shade of red at all ports, or is it different at different ports?
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Old 05-23-2006, 03:53 PM   #10
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Is your cat plugged.
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