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Thread: 89 Lancer Shelby Very High Idle

  1. #1
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    89 Lancer Shelby Very High Idle

    Just got the White Brick back from my son. It had a coolant leak, fixed that, decided to take the car out for a drive. I had it running at the usual 750 rpm idle in the driveway for about 10 minutes, took it out to the main drag, ran it through the gears a few times, no problem. Then I decided to wind it out a bit, shifting at the top of the reasonable rpm range and then it started to "idle" at 4000 rpm. Just stayed there. Bumped the accelerator to see if I could un-stick it, no dice. Managed to get the thing home without over-heating, parked it in the driveway. Let it sit for about half-an-hour. Started it again, 4000 rpm... Jumped out, checked the throttle and cables, not stuck on WFO. Turned off the car, pulled the air plenum that comes from the inter-cooler to the throttle body. The throttle plate was closed, as it should be when the engine is not running. Opened and closed it with the the cable cam (my word), closed like it should. Started the engine, 4000 rpm with the throttle plate CLOSED!!! I put my hand over the throttle body opening to cut off the air to the engine, I could feel some vacuum (but not what you would expect at 4000 rpm) and the motor never slowed down. It was obviously getting all the fuel/air mixture it could burn. Turned the car off, went inside to watch TV (Crossbones finale, complete waste of time). Went to bed, got up, went to work, came home, started car, 4000 rpm. It seemed to be making some effort to bring the idle down but just a touch of the accelerator maxed it out again, 4000 rpm. So, I am thinking choke, whole bunch of air coming from somewhere, computer, MAS, sending much fuel, etc. So, before I start ripping things apart, has anyone else experience this? If so, what do you recommend checking at this point? Thanks, John in Charlotte, NC.

  2. #2
    Supporting Member II Turbo Mopar Contributor ajakeski's Avatar
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    Re: 89 Lancer Shelby Very High Idle

    Most likely cause of high idle is a vacuum leak. Check your vacuum hoses.
    An intake manifold vacuum leak will give a high idle because the leak is allowing air into the manifold, just like an open throttle plate would.
    Last edited by ajakeski; 08-05-2014 at 07:15 PM.

  3. #3
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    Re: 89 Lancer Shelby Very High Idle

    Quote Originally Posted by hewhobarksatdogs View Post
    Just got the White Brick back from my son. It had a coolant leak, fixed that, decided to take the car out for a drive. I had it running at the usual 750 rpm idle in the driveway for about 10 minutes, took it out to the main drag, ran it through the gears a few times, no problem. Then I decided to wind it out a bit, shifting at the top of the reasonable rpm range and then it started to "idle" at 4000 rpm. Just stayed there. Bumped the accelerator to see if I could un-stick it, no dice. Managed to get the thing home without over-heating, parked it in the driveway. Let it sit for about half-an-hour. Started it again, 4000 rpm... Jumped out, checked the throttle and cables, not stuck on WFO. Turned off the car, pulled the air plenum that comes from the inter-cooler to the throttle body. The throttle plate was closed, as it should be when the engine is not running. Opened and closed it with the the cable cam (my word), closed like it should. Started the engine, 4000 rpm with the throttle plate CLOSED!!! I put my hand over the throttle body opening to cut off the air to the engine, I could feel some vacuum (but not what you would expect at 4000 rpm) and the motor never slowed down. It was obviously getting all the fuel/air mixture it could burn. Turned the car off, went inside to watch TV (Crossbones finale, complete waste of time). Went to bed, got up, went to work, came home, started car, 4000 rpm. It seemed to be making some effort to bring the idle down but just a touch of the accelerator maxed it out again, 4000 rpm. So, I am thinking choke, whole bunch of air coming from somewhere, computer, MAS, sending much fuel, etc. So, before I start ripping things apart, has anyone else experience this? If so, what do you recommend checking at this point? Thanks, John in Charlotte, NC.
    Just saw this: http://www.turbo-mopar.com/forums/sh...er-a-long-ride

    So where is the AIC located?

  4. #4
    Supporting Member II Turbo Mopar Contributor ajakeski's Avatar
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    Re: 89 Lancer Shelby Very High Idle

    Most likely cause of high idle is a vacuum leak. Check your vacuum hoses.
    An intake manifold vacuum leak will give a high idle because the leak is allowing air into the manifold, just like an open throttle plate would.

    There is no choke or mass airflow sensor on our Lancer. Turbo Mopars measuse the air density method of fuel injection.
    Last edited by ajakeski; 08-05-2014 at 07:15 PM.

  5. #5
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: 89 Lancer Shelby Very High Idle

    Quote Originally Posted by hewhobarksatdogs View Post
    Just saw this: http://www.turbo-mopar.com/forums/sh...er-a-long-ride

    So where is the AIC located?
    Defintitley check this. The AIS is below the TPs on the throttle body. It can be a real pain due to the torx bolts not wanting to come out. Once it's out spray the AIS nub and the AIS holt in the TB with carb cleaner and reinstall. Then follow this procedure.

    http://www.turbo-mopar.com/forums/kn...dle-Adjustment

    Although you should check for any vac leaks first since you stated that you went for a WOT run before this happened. As stated the vac leaks are also a primary cause of a high idle.

  6. #6
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    Re: 89 Lancer Shelby Very High Idle

    Even if it was the AIS, the idle would have come down when he choked the TB with his hand. There for I'm thinking there is a vac leak after the TB. Could be the PCV, vac line...ETC but definitely something after the TB, on the monifold or to the manifold.

  7. #7
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    Re: 89 Lancer Shelby Very High Idle

    vacuum leak! looking down at the engine, about 6" from the left end of the intake manifold is an L shaped steel pipe, about 3/8" that popped out of the manifold. when I originally put the head back on the car after 3-angle valve job from speed shop in Vegas (head gasket failure led me to that) I installed that pipe with a bit of orange RTV. looks like it might need something with a bit more stick this time. any recommendations on an adhesive that will stand the heat, etc. without bonding permanently to the manifold?

    - - - Updated - - -

    Cordes, you are right. The torx bolts are in there with blue loctite. Got it out, looks good , will follow your instructions for cleaning, etc. when I replace it.

  8. #8
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    Re: 89 Lancer Shelby Very High Idle

    Loctite 640

  9. #9
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    Re: 89 Lancer Shelby Very High Idle

    Have fixed the leak, cleaned the AIS, re-setting idle, but need to know if the idle screw is under that little metal plug at the left top of the throttle body. Don't want to pry it off if it is not the right thing...

  10. #10
    Supporting Member II Turbo Mopar Contributor ajakeski's Avatar
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    Re: 89 Lancer Shelby Very High Idle

    The idle screw is under that plug.

    here is the procedure for setting the base idle:

    1. With the car up to temp in neutral and running, unplug the line to the brake booster. The car will rev really high. Let it do that for several seconds. This will cause the AIS to close all the way allowing for a true adjustment of the base idle with the TB screw.

    2. Unplug the AIS and then plug the vacuum line back in. The idle should come back down near normal. If the car stalls, try to start it back up. You might need to open the TB with a screw driver, or more likely a torx bit for it to stay running if it's really far out. If there is a cap over the adjustment screw still just pry it out with an appropriate sized screwdriver.

    3. With the car running, and the AIS still unplugged, adjust the idle to 900RPM.

    4. Turn off the car and plug the AIS back in.

  11. #11
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    Re: 89 Lancer Shelby Very High Idle

    I've heard not to mess with that screw as you could end up chasing your tail.

  12. #12
    We Todd D dot D Turbo Mopar Staff sdac guy's Avatar
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    Re: 89 Lancer Shelby Very High Idle

    Quote Originally Posted by going4speed View Post
    I've heard not to mess with that screw as you could end up chasing your tail.
    That could be true if you do not follow the procedure 'cordes' and 'ajakeski' listed. But the procedure they listed is the correct way to set the base idle.

    Barry
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  13. #13

    Re: 89 Lancer Shelby Very High Idle

    I drilled a hole through the center of that bolt, added a nipped in the hole and use that for the external wastegate for my car now. That was going to be my suggestion, but only because I'm using mine for vacuum/pressure.
    [SIZE="3"] [B]Jon Trotter[/B][/SIZE] [B]1985[/B] Dodge Shelby Charger, Currently decommissioned [B]1987[/B] Shelby GLHS, #937 [B]1987[/B] Shelby Lancer, #628 [QUOTE=Reeves;587010]I can be ready. Please send pics of wife. _____DodgeZ add comments here______[/QUOTE]

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