Question about 1981 Chevrolet Corvette

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1981 Chevrolet Corvette runs "rich"

I have a 1981 cross-fire corvette. It has an exstreme rich run problem at idle and mid throttle. The TPS, fuel pressure, ECT sensor, and oxygen sensor reads within manufacturers specifications. The rich run occours during open and closed loop operation which eliminates the oxygen sensor. My concern is the map sensor, what are acceptable specs? I can't find them. A dealership suggested a valve job, claiming it had sticky vavles. I removed several rocker arms and used a valve spring compressor to check for sticky valves and found them to be all ok. The vehicle also has good compression on all cylinders. I am an ASE master certified technician and this car is making me lose my mind! I am very limited to the informatoin availible and am embarrassed with my inability to find the problem with this vehicle. Any information would be greatly appreciated. Thank You in advance.

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A vacuum leak would cause a lean run condition so stormbrewin is of base there, I would have the MAP sensor tested ( to many years not sure of the specs) and also see if the injectors leak when engine is shut down, these fuel injectors in this throttle body system had there problems, leaking around the injector O ring seals is common, this causes a very rich run condition. Have you run the codes?

Posted on Oct 22, 2008

  • yadayada
    yadayada Oct 22, 2008

    I have the original GM technicians book from tech school in 1981 on the trouble shooting of your fuel injection system, so I can give you detailed procedures to run down and fix any trouble codes present in the processor, code 34 is the MAP sensor, is this or ever has this been a code you got??

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Have you done an engine vacuum leak test with carby cleaner especially around injector seals.A leak will throw a lean signal to oxy sensor there by telling the computer it needs more fuel.Cant think of anything other than what you have already done.

Posted on Oct 22, 2008

  • tony yeatman
    tony yeatman Oct 22, 2008

    Im assuming that injectors and pressure reief is in a servicable condition?

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