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Discussion Starter · #1 ·
My buddy's supra was running between 10.0-10.5:1 air/fuel ratios on the dyno yesterday, which is a little ridiculous. I was wondering if there is any easy/inexpensive way to lean out the entire fuel curve a bit. What if we cut the signal wire from the stock MAP sensor and put a potentiometer in the middle? Would that allow us to trick the ECU into to thinking there's say 16 psi instead of 18? What about if we modified the signal from the MAF instead? Or would we have to modify both?

Obviously it's not going to be as good as using a fuel computer... but if we could get the a/f into the 11's at least that would be great.

-Paul
 

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Old School
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How much power was he making, and what gas was he using?

Car may be pig rich due to a boost leak, or the ECU may be pulling timing and dumping fuel due to preignition on low octane pump gas.

Doing fuel tuning may not be the first thing to look at.

My car doesn't drop below 11:1 until over 6k rpm, FWIW
 
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Discussion Starter · #3 ·
Actually we found that he did have a boost leak, so maybe that accounted for some of the extra fuel. One of his rubber IC pipes was ripped at the end. I don't think the gas was an issue. He was using at least 93 octane and only running 15 psi or so.
 
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