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runs rich under accel 700

i have been figting a lossing battle with my 85 740t. I did manage to find some leaks under boost, and repaired them. As i was driving home from the store tonight i think i figured it out. as the rpm's hit 2800 to 3500, the car breaks up real bad, blowing black smoke behind me (fuel). I remember i had a mustang that did almost the same thing, just couldn't tell if it was running rich. It turned out to be the plug wires on the ford. I have bougee (sp?) cord wires on the 740 and are in real good condition. But the cap and rotor is a different story, i found it real loose and not sure how long it was like that. Like the big dummy i am, i just tighened it up, with out checking it? Do you think i found another one of my problems?


Dave Barcomb
Charlotte NC
--
85 740 b230f+t








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    runs rich under accel 700

    My 740T did this, I thought it must be a hose leak, turned out to be the fuel pressure regulator. Might be worth checking your fuel pressure.








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    runs rich under accel 700

    You've still got leaks in the intake plumbing, and they aren't fixed. Buy new hoses.

    This is what happens: The turbo sucks air through the air box and the air mass meter (AMM). It goes into the turbo and gets compressed. ALL of that air is measured by the AMM. Then the compressed air goes out of the turbo to the intercooler, through a hose that can leak. Then out of the intercooler to the intake, through 2 hoses that can leak and a pipe. Then, the intake has a bunch of vacuum hoses that can leak, a manifold gasket that can leak, and the fuel injectors have seals that can leak.

    When the engine is idling, it makes vacuum. That means inside the whole intake setup there's negative pressure- any leak makes air get pulled into the intake, and makes it a little lean. No big deal. Under boost, however, those leaks mean pressurized air is blowing out, and not being fed into the engine. But the fuel computer already did it's calculations based on what that AMM saw- so it dumps in fuel, making the mixture go very rich. And it gets worse the more you press on the throttle.

    Fix the leaks, it'll be all bettah!
    --
    Rob Bareiss, New London CT ::: Roterande Fläkt Och Drivremmar!







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