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  1. #1

    Default Rough Idle-EGR Diagnosis '94 suburban

    Stock 94 sububan, 2WD, 350 V8.
    The check ingine light comes on after 20 minutes of driving, pulled codes using paper clip method and EGR is suspect.
    Using the Chilton's manual I performed the 2 checks they describe for checking the EGR.
    1. With truck idling. Use vacuum pump on the EGR to see if idle changes. The vacuum made the truck idle real rough, if this happens EGR is good.
    2. Unplug vacuum line on intake side of EGR and test for leakage, no leakaage detected.
    So, my question is, what next. The manual says to take vehicle to a dealer or repair shop to diagnose ECM.

    Any other options??


  2. #2


    I'm very interested to hear anything on this subject also. I have the same exact problem in my 95.

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