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Old 05-29-2009, 12:03 AM   #1
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Default 5000+rpm richness

Like the title says, I'm running rich (10.0-10.4:1) above 5000rpms all the way to red line, and its killing my power, I think my cars faster if I shift at 5k than if I go to redline. I have the setup that's in my signature, with the BEGI afpr. I recently adjusted the base fuel pressure to tune out a lean spot where the fpr would take over. It would go mega lean (14+:1) for a few seconds and finally stumble into a tune and run great, (12.0-12.5:1) to red line, pulling hard the entire time.

Since I've adjusted the base pressure, from about 43psi to 48psi, the lean hesitation is gone, and it transitions great into boost, making it a much more drivable car on the streets. However once I was on the track, I found out that the range you don't use much on the street (you don't if you don't have a muffler at least) which also happens to be the range I need on the track, was pig rich. I tried adjusting the needle valve way out and it doesn't seem to affect it what so ever. It might have jumped from 10.0 to 10.4:1, but that's hardly a change and could have been just run to run inconsistencies. Anyone have ideas as to why this is happening and what I can do to fix it? I could keep adjusting the needle valve out, but it seems like its fairly far out, and it didn't seem to be doing much. I'm hesitant to adjust the base pressure lower again and hit that lean transition issue again. Ideas?
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Old 05-29-2009, 01:38 AM   #2
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Sounds like you need some sort of piggy back ECU or stand alone ECU to lean out your top end. Don't think there's much more you can do with your current setup.
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Old 05-29-2009, 01:58 AM   #3
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You're right, this type of band aid setup has never worked before. Ever. Anyone with experience have some tuning ideas?
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Old 05-29-2009, 02:25 AM   #4
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The stock ECU adds fuel automatically above like 4900 RPM or so. I'm guessing that's the reason your going rich up there.
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Old 05-29-2009, 10:08 AM   #5
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Quote:
Originally Posted by nicacus View Post
The stock ECU adds fuel automatically above like 4900 RPM or so. I'm guessing that's the reason your going rich up there.
its not that it adds fuel, it goes into open loop mode and fuels off a map coupled with high fuel pressures you pretty much always go rich.

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Old 05-29-2009, 07:42 PM   #6
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See that's 11.4:1, which I would be thrilled to have, and it was running great at 11.4:1, but that lean transition completely killed all power until it fought it's way through than ran like a bat outta hell at 11.4ish.

I think I'm just going to put my fuel pressure gauge on, and tune it down a psi at a time to try and get rid of this rich bog up top, and hopefully when I do it'll still be high enough to not have too lean of a transition. We'll see.
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