What could be wrong causing High Idle all the time 2000-2800rpms?

all time high
CanadianPirate asked:

It is my 1988 Chevy Camaro IROC w/ a 350 TBI dual injectors.
Just recently The Engine will start up & never Idle back down. I have done many things to try to fix this. You can smell excessive fuel odors comming out of the exauhst; so I know the engine is getting way to much fuel at start up & never comming back down. I rebuilt the TBI unit about 1 year ago, & also changed all the sensors on the unit inculding the MAP sensor & a few others including the O2sensor. Just recently after the problem has started I’ve put in a new IdleAirControl & a new O2sensor. I’ve checked/cleaned/&lubricated the cables & linkage on & around the TBI unit. Starting the engine cold I could tell that the butterfly’s(plates) did not open up after warm-up, the plates remained fully closed in the horizontal position. I’m thinking it has something to do with that, because I’ve also hooked up a computer to read the Codes, & the only thing that came up was the MAT sensor low & O2sensor reading rich



Comments (8)    Posted in Maintenance & Repairs    

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8 Responses to 'What could be wrong causing High Idle all the time 2000-2800rpms?'

  1. ben s - September 21st, 2009 at 9:51 am

    you need to pull back the wire on the throttle and fix the govoner

  2. Mai N - September 23rd, 2009 at 7:07 am

    You have a vacuum leak somewhere, look for creaked/lose hose, then check your TPS.
    Good luck
    See if these guys can help

  3. carvinmark - September 25th, 2009 at 3:21 pm

    Sounds like a vacumn leak. Check all lines. check PCV valve

  4. taknadvantageof - September 28th, 2009 at 12:00 am

    you need to check the fuel regulator spring in the throttle body to see if it broke, if it is broke it will allow more fuel to the injectors, the spring regulates the pressure

  5. no1shthead66 - October 1st, 2009 at 6:54 am

    have you tried spraying WD40 on the butterfly of your carburetor. sometimes they stick real bad. you may want to also try checking your bolts and screws to the surrounding parts to make sure they aren’t too tight.

  6. just my answer - October 2nd, 2009 at 5:32 am

    ON FUEL INJECTED VEHICLE THERE IS A LOT OF THINGS THAT COULD CAUSE THAT PROBLEM
    MOST COMMON IS PROBABLY A VACUUM LEAK…THIS WOULD ALSO AFFECT YOUR O2 READING
    OTHER COMMON POSSIBILITIES ARE TEMPERATURE SENSOR CIRCUIT, (SENDING MESSAGE TO ECM THAT ENGINE IS STILL COLD….INCREASED RPM)
    THROTTLE POSITION SENSOR CIRCUIT, (TELLING ECM THAT THROTTLE IS DEPRESSED)
    BEST THING IS TO PAY A PROFESSIONAL
    THEY SPEND LOTS OF MONEY AND TIME BEING EDUCATED TO DEAL WITH THESE PROBLEMS

  7. B H - October 3rd, 2009 at 12:30 am

    You still may have a leaking injector. Also check the temperature sensor that goes to the computer,(not to the gauge) 2 wires probably a yellow and a black if this sensor goes bad it will tell the computer that it is 40 degrees below zero, and it will dump extra fuel ( this system is what replaces the choke) on fuel injected engines. Did you check the MAFF sensor if you have one? I’m not sure if IROC used this sensor.

  8. Zack S - October 5th, 2009 at 4:45 pm

    It’s probably a vacuum leak.

    How to tell: Spray some starting fluid around possible points of suspicion. Like the throttle body itself. If the engine rev’s then you know the starting fluid is getting in the engine and it’s not sealed.


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