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AFR question after intercooler + more boost...FIXED

Discussion pertaining to positive pressure E28s.
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Kyle in NO
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Joined: Feb 12, 2006 12:00 PM
Location: Nasty Orleans------> Batten-Rooehjch------>More Souther LA

AFR question after intercooler + more boost...FIXED

Post by Kyle in NO »

Here is what is happening now after intercooler installation and upping boost from 12 to 14psi on the TCD S2 kit...

As the revs climb, the AFRs climb to about 13.9 in the midrange, and then drop back down to about 12.5 as it approaches redline. I turned in the FMU's bleed screw a quarter turn, then a half turn, and finally a full turn, and it did not seem to make a difference. Therefore, I backed the bleed screw back out all the way again. I don't think I'm running out of fuel capacity, because it looks like the normal 12.4-12.5 near the redline...

It runs hard, but obviously something needs to be adjusted. I figured it was the FMU bleed screw, but I really don't know. Do I need to turn in the bleed screw more so that the richening comes on sooner? Suggestions?
Last edited by Kyle in NO on Sep 22, 2007 12:06 PM, edited 1 time in total.
Mark 88/M5 Houston
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Location: Far North Houston

Post by Mark 88/M5 Houston »

Wasn't Greg having a similar problem when he installed his system over here in Houston?
Kyle in NO
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Joined: Feb 12, 2006 12:00 PM
Location: Nasty Orleans------> Batten-Rooehjch------>More Souther LA

Post by Kyle in NO »

Somewhat, but mine is not as severe as his was. I think he had a bad TPS in which the WOT was non functional. This made the Motronic brain try to keep the mixture at stoich until he hit about 4700 rpm or so...

EDIT: Fixed the problem....3 turns on the bleed screw did the trick...
Boru
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Post by Boru »

Good job! Is it "peppy" now?
Kyle in NO
Posts: 17638
Joined: Feb 12, 2006 12:00 PM
Location: Nasty Orleans------> Batten-Rooehjch------>More Souther LA

Post by Kyle in NO »

Oh yes, quite peppy! I think we will be going to the track on Wednesday to see just how peppy...
Jeremy
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Beamter
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Post by Jeremy »

What "bleed screw"? The one on top of the housing? If so, that controls rise right at atmospheric (0 psi), and has nothing to do with rpm. The only way to adjust the mixture with regards to specific rpm is to get a custom chip burned or use some sort of piggyback system. Standalone being the ultimate solution of course. ;)

Jeremy
Kyle in NO
Posts: 17638
Joined: Feb 12, 2006 12:00 PM
Location: Nasty Orleans------> Batten-Rooehjch------>More Souther LA

Post by Kyle in NO »

The richening just was not coming on soon enough, ie the little bleed screw on the side of the FMU (the one that is usually backed all the way out) was open too much. Turning it in slows down the bleed and causes the richening to come on sooner...
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