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  • 3.8 chevy v-6 rebuilt, wont hold idle!!! arhhhh

    SO... my brother and i rebuilt his 3.8 V-6 in a 2000 camaro due to a spun rod bearing.
    After getting it all back together, it wont hold an idle, it just starts up then dies right off, even after throttling it up and trying to go back to idle it dies!
    But I did find out that if you pull the brake booster vacuum line, it will stay running, but obviously sparatic idle due to an unmetered intake of air.
    To me it seems like an idle air sensor, or the throttle position sensor.
    If anyone has an idea of suggestion, id be more than happy!

    Thanks,
    Robert

  • #2
    when you throttle up does it run smooth?

    ive rebuilt one of those engines, last year. i cant remember if it has an adjustable TPS or not, if it does the holes through it where the screws mount onto the throttle body will be elongated. it will need to be properly set. if they are not you can test it either by making a jumper or using a tech scanner. usually at idle they should throw about .45-.5 volts. at WOT they are about 4.7 - 4.9 volts. if it shows 5 volts or .2 volts at idle you probably have a problem. the IAC valve can usually be clean, take it out and hit it with carb clean and blow it off. there is a procedure to reset it properly which should be in the service manual.

    however, could be internal, could be a vacuum leak (you should test that). o does that have coil packs or distributor? if it has a distributor you should check base and advanced timing. could also have a problem with MAP sensor, MAF sensor, temp sensor, knock sensor, etc. most of those last problems will require a tech scanner to easily diagnose.

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    • #3
      Brian,
      It does throttle up smooth, however, it doesnt have an adjustable TPS, and I have cleaned the IAC.
      There isnt a known vacuum leak, as their is really only one vaccum line that services three runners, but all are connected.
      It has coil packs, and is a booger to work on! Half the engine is under the front glass!! Damn cab forward designs!!!

      Well off to get my hands dirty again!!
      Last edited by hazyredeyes; 09-11-2005, 02:06 PM.

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      • #4
        I'd aim at the TPS, Idle air valve, Air flow sensor or even the MAP sensor.
        If you are dicso-ing the brake vac and it runs, the Maniforld Actual Pressure [map] could be bad.

        Tap the Idle air with a light hammer and see if she idles...

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        • #5
          ODDEST SOLUTIONS FOUND IN THE STRANGEST WAYS!!

          Well, we decided to go get it scanned. Welded the exhaust back up to get it to my mechanic, and woolaahh...... It runs better than it did before the spun bearing. I suppose it has to have a back pressure reading..... DUHH!!!

          Leaned a good one their, but thanks for the tips you guys left.

          Robert

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          • #6
            Easy... its a Chevy! j/k

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