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Surging Idle after Rebuild

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    Surging Idle after Rebuild

    Hereís the details: 1990 (10/89) 325i Convertible
    Just finished refreshing the motor: rebuilt head w/ 272 cam & HD rockers etc, all new belts, wires, cap&rotor - the works in other words. Get it all back together and it idles like total crap. Surges from 500-650 constantly. Once you get the RPMs up its better.

    Get it smoke tested and find a bunch of leaks - bitch tube etc. Fixed those and it idles better but not great. It idles like a 1/4 mile drag car - lopey. Mechanic thinks itís fuel (car has 208k on it). So I swap out the original injectors for some new Bosch units and swap the TPS. Still no love.

    So I start testing the ICV (three wire). Voltage and resistance check out and I double checked the TPS as well - both good. Bentley says the ICV should be partially open with a warm engine and the key on. Mine snaps closed as soon as the key is turned to the on position.
    Is this the issue?

    Thx, Pat

    #2
    Are lifters are adjusted properly??

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      #3
      Surging is a sure sign of vacuum leaks post-AFM on these cars.
      john@m20guru.com
      Links:
      Transaction feedback: Here, here and here. Thanks :D

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        #4
        Smoke tested and fixed the leaks. After running for a few days the surging is gone but itís a really lumpy 700ish rpm idle. I didnít think a 272 cam would make it that bad. Itís stock (for the moment) other than the cam. Is this something that would be cured by a ssquid chip? Or should it idle better even with the 272?

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          #5
          Chip to bump up idle speed
          89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

          new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

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