Idle Adjustment ?'s

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  • winstontj
    E30 Addict
    • Mar 2007
    • 500

    #1

    Idle Adjustment ?'s

    Books say there are all sorts of gadgets to adjust idle that mainly measure CO2 levels or something if I understand correctly.

    To adjust the idle on an IS car is it as easy as adjust the TB and TPS? Is there anything else I should worry about? Right now the idle is lurking just a hair over the 500 mark and I want it at ~750 (book says 760) right?

    Just worried about doing this properly as I am due for an inspection shortly and do not want to mess up anything.... I know these cars can be tempermental.

    Thanks for any help you can offer....
  • NC325iC
    R3V OG
    • Mar 2004
    • 6565

    #2
    you can use the TB adjustment screw to bump it up some but this will likely only make your cold idle crazy high and your warm idle normal
    hows your o2 sensor?
    Your signature picture has been removed since it contained the Photobucket "upgrade your account" image.

    Originally posted by TimKninja
    Im more afraid of this thread turning into one of those classic R3v moments, where Pizza gets delivered.

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    • winstontj
      E30 Addict
      • Mar 2007
      • 500

      #3
      Originally posted by NC325iC
      this will likely only make your cold idle crazy high and your warm idle normal
      was afraid of that. can you turn down the ICV & cheat it?

      Originally posted by NC325iC
      hows your o2 sensor?
      PO said recent within the last year... Perhaps it's time for a new one? If it's the o2 than emissions test will be interesting....

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      • jlevie
        R3V OG
        • Nov 2006
        • 13530

        #4
        The adjustment screw is only there to set the minimum position of the throttle butterfly. Idle speed on an M20 is controlled by the DME (or separate idle controller on earlier production). For the system to work properly the throttle stop and TPS must be correctly adjusted and the idle control valve must be operating properly. Randomly fiddling with the throttle stop can result in an unstable idle as the DME tries to achieve the idle rpm it is programmed for.

        The adjustment procedure is in the Bentley.
        The car makes it possible, but the driver makes it happen.
        Jim Levie, Huntsville, AL

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        • winstontj
          E30 Addict
          • Mar 2007
          • 500

          #5
          The throttle plate is adjusted properly and TPS is adjusted properly. I have noticed a small leak between the manifolds & the downpipe flanges - this could be a concern. Also I need to adjust the valves. I'm going to go adjust the valves now and I'll see this weekend about the o2 sensor. Is it possible to look at the o2 sensor to know whether or not it needs replacing (read it like you can read plugs?)

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