Argh, freakishly high idle - 205
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  1. #1
    Fellow Frogger! Cubits's Avatar
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    Default Argh, freakishly high idle - 205

    I was just driving to the shops today, when i nearly stalled coming out of a junction. I did my usual "save" and jumped on the clutch to keep it alive, only to have the revs fly to 5000rpm and not come down!

    I shut the engine down and rolled it to the kerb to inspect. Upon restarting the revs flew up again.

    I checked the throttle cable all the way to the engine, (removed the air pipe to see that the throttle was indeed closing).

    What would cause this?



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  2. #2
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    Just driving to the shops ,eh? Was the car nice and warm or did you roar off from cold? Sometimes my Mi16 gets a little confused in the same circumstances and the mixture seems wrong when you drive away. Try cleaning the idle valve stepper motor thingy of gunk and giving it a squirt of lanox or similar. It works for me Cheers Greg

  3. #3
    Fellow Frogger! Cubits's Avatar
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    Where is said stepper motor? My haynes manual is less than useless at locating things like these :/

  4. #4
    Moderator Alan S's Avatar
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    Standing in front of the car, it's the round alloy thing with a pipe in & one out and a plug in one end just right of centre sitting on top of the intake manifold.
    Pull the pipe off the end & stick your finger in it; it rolls like a cylindrical thing.

    Shown here just in front of the yellow dipstick and alongside the oil filler cap.



    Alan S
    Last edited by Alan S; 14th May 2004 at 02:18 PM.
    If it ain't broke, use a 12" shifter.....that usually does the trick!!

  5. #5
    Fellow Frogger! Cubits's Avatar
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    The 8v is seriously different to the 16v in layout! The motor was noowhere to be seen. I removed a few pipes to see if it was hiding under one, but to no avail.

    Here are some photos with the pipes removed (and no, i didnt remove the motor by accident).





    Theres a thin black thing on the front of the intake manifold, directly opposite to the throttle cable pulley, and below the idle screw, with a composite plug in it (kinda like the one on the motor/ecu). Any idea what that is?

  6. #6
    Tadpole
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    Default What a minute....

    If yours is a 205 with an 8 valve engine it won't have a stepper motor. If it's a 16 valve it will and therefore ignore what i'm about to say...

    The auxilary air valve used on the 8 valve is located above the clutch towards the rear of the head. Often the air pipes (approx 18mm) connecting it develop holes/splits etc with can couse the revs to hold high. Check the pipes for damage but also listen for a hissing air sound if you can hear anything above the roar. It's unlikely the air valve has stuck open but if u cannot find anything else it's likely. To check the air valve, remove it from the vehicle. (it's a cast alloy object the size of a child's fist). Apply 12 volts across it's two electrical pins and wait a few minutes before checking that the shutter inside has closed. It may not seal fully but u'll notice it will close 97%. If it makes no attempt to close, get another one. If it does close and nothing else appears wrong check it's power supply plug for power. I'm not sure if the engine needs to be running.

  7. #7
    Fellow Frogger! Cubits's Avatar
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    The fact that it has pulled this stunt once before (but only momentarily) would indicate that it is indeed the valve which is toasted.

    I don't think i could hear the hissing over the revs, and i wouldnt want to inflict my engine with 5000rpm from a cold start to try to listen under the bonnet (poor car!).

    I'll rip out that valve and have an inspection of the pipes.

    These things aren't that expensive, are they?

  8. #8
    Moderator Alan S's Avatar
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    Doh!! Don't mind me. I saw the Avatar & had it in my head you had an 205/Mi16 conversion.
    Check out what has been suggested but also just check that the throttle is back at its stops when the car is stopped.
    I have had these pop the outer throttle cable at the firewall; what happens is that it somehow can get on the outside of a short tube that it fits into which of course can hold it open. Another one is the quadrent where the inner cable goes around at the throttle body can sometimes jump half out & again hole the butterfly open.
    A good starting point is to disconnect the throttle (accellerator) cable at the engine end & see if the butterfly then returns to its stops. If it does, then you know it's external to all the sensors and the like; if not, then's the time to go looking for a more devious culprit.
    Sorry about the bum steer.


    Alan S
    If it ain't broke, use a 12" shifter.....that usually does the trick!!

  9. #9
    Fellow Frogger! Cubits's Avatar
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    How did my avatar give that impression? :p

    Anywho, i fixed the idle. It turns out the throttle cable outer casing had jumped out of its recess at the throttle body end, causing it to not close enough. Once i popped that back in (and secured it!) all was well.

    Thanks guys. If i ever get a 16v conversion, i'll know what to do then too :p

  10. #10
    1000+ Posts Luca's Avatar
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    Get some degrease on to that engine bay as well mate... It looks like it could do with some love.

  11. #11
    Fellow Frogger! Cubits's Avatar
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    Yeah yeah yeah....

    It'll get some love once i've replaced all of the hoses that are leaking oil (tiny amounts, but enough to dirtify the engine). :p

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