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  1. #1
    Saab Psycho bullet's Avatar
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    1996 NG900 2.0 Turbo automatic
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    Unhappy High idle issue

    Hi all ,

    About a month or so I decided to clean the throttle body on my 1996 NG900 Turbo Automatic. After the job was done, I noticed that in Park or Neutral the idle went up from 900-1000 rpm to almost 2000 rpm. After this, I thought it was a vacuum problem, so I checked all the vaccum lines, changed the throttle body seal and the IAC valve, but to no positive result.

    This is how the engine idles while stationary (when I select Drive the revs drop)

    Idle while stationary.3gp - YouTube

    This is the idle while driving, and moving the selector from Drive to Neutral. The revs just go up and down.....

    Idle while driving.3gp - YouTube

    I also noticed that while the car is in Drive and moving at slow speeds, it's like someone is pushing it from behind and if I take my foot of the brake it gathers quite a lot of speed, to almost 40 km/h without accelerating !!!

    Here is an example:

    Speed gain in "Drive" without accelerating .3gp - YouTube

    Any ideas to what might cause this ?

    PS Sorry for the poor quality of the videos.

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  2. #2
    Saab Psycho bullet's Avatar
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    1996 NG900 2.0 Turbo automatic
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    So, from the various advice I got, I checked the CEL with the ignition on and there are no errors.
    I also checked the butterfly valve at idel, and its fully shut.

    One thing I did notice though, that the engine idles like it should until it gets warm. As soon as it reaches normal operating temperature, the idle shoots up to 2000 rpm. Funny thing this, as I changed the coolant temperature sensor just 5 months ago.

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  3. #3
    Mike
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    Try cleaning the idle air control valve (IAC). Just take it off, and clean it with some warm water and mild soap mix.

    It's on top of the intake manifold, and looks like this:

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  4. #4
    Saab Psycho bullet's Avatar
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    1996 NG900 2.0 Turbo automatic
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    Hi,

    I wrote in the first post that the IAC Valve has been changed (with one bought from ebay, from a reputable seller). But it made no difference whatsoever to the car's problem.

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  5. #5
    Mike
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    That's what I get for skimming, and not reading. I'm outta ideas already. You've done everything I would have.

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  6. #6
    Jose Luis
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    2007 93 Aero 2.8 V6
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    Quote Originally Posted by bullet View Post
    Hi all ,

    About a month or so I decided to clean the throttle body on my 1996 NG900 Turbo Automatic. After the job was done, I noticed that in Park or Neutral the idle went up from 900-1000 rpm to almost 2000 rpm. After this, I thought it was a vacuum problem, so I checked all the vaccum lines, changed the throttle body seal and the IAC valve, but to no positive result.

    This is how the engine idles while stationary (when I select Drive the revs drop)

    Idle while stationary.3gp - YouTube

    This is the idle while driving, and moving the selector from Drive to Neutral. The revs just go up and down.....

    Idle while driving.3gp - YouTube

    I also noticed that while the car is in Drive and moving at slow speeds, it's like someone is pushing it from behind and if I take my foot of the brake it gathers quite a lot of speed, to almost 40 km/h without accelerating !!!

    Here is an example:

    Speed gain in "Drive" without accelerating .3gp - YouTube

    Any ideas to what might cause this ?

    PS Sorry for the poor quality of the videos.
    Throttle Body Sensor Code - SaabCentral Forums

    http://www.saabcentral.com/forums/sh...1&postcount=42

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  7. #7
    Saab Psycho bullet's Avatar
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    1996 NG900 2.0 Turbo automatic
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    @jlrsaab

    Thanks, but my car doesn't have that type of sensor. Mine is a 1996 B204L with Trionic 5. It doesn't have any type of sensors inside the throttle body.

    And the curious thing is there are no error codes, not one !

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  8. #8
    Mike
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    This probably isn't going to work, but worth a shot. Try resetting the ECU by disconnecting the battery for 15 minutes, then hook it all back up. Do a couple hard/full throttle runs (if you can find a place), and see if that works. I doubt it will, but for something so easy, it's worth a shot.

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  9. #9
    Saab Psycho bullet's Avatar
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    I've already done that a couple of times, didn't made any difference.

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  10. #10
    Mike
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    What I figured... I've been searching online, and you've done what everyone recommends. I can't find much else on the issue.

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