Digifant Idle at 2.5-3k When Warm

Discussion in 'Engines' started by nickh89GTi, Jul 3, 2008.

  1. RIP-MK3 Forum Addict

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    i don't think this is an isv issue myself, more likely a temp sensor or similar
     
  2. nickh89GTi Forum Member

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    Hey MK3valver, thanks for you reply mate. I'm hoping its jus a poor quality temp sensor from GSF.

    My mate set up all the ignition timing and fuelling/airflow etc a couple months back and i checked the ignition timing this morning as per rubjonny's FAQ and was to far advanced. I then phoned him and asked him if he had set it like it and he said it was smack on the marks as it should be. Could this be linked to my problem?

    Cheers guys

    Nick
     
  3. rubjonny

    rubjonny Administrator Staff Member Admin

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    did he follow my guide when he set it up though, or did he set the timing at idle? I'd replace the sensor with a VW one as the GSF ones are known to be a bit pants, though your problem does not sound like an issue with the sensor. usually when the sensor goes its hard to start rather than high idle.

    If the timing was set up properly by your mate then it could be that your dizzy is loose or perhaps your cam or crank sprocket is moving thanks to a damaged/missing key...
     
  4. nickh89GTi Forum Member

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    I don't really now if he done it as per your guide, he's not the sharpest tool in the shed :lol:. I expect he has done it at idle speed as i didn't have your guide to leave for him. I assumed he would know what he was doing as he works in a tuning garage.

    All the timing marks line up spot on i checked when i was looking at it yesterday. Its really weird because if you leave it for 5-10 mins after it is up to temp then start the car it idles fine.

    Cheers Nick
     
  5. rubjonny

    rubjonny Administrator Staff Member Admin

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    reset the ign timing as per me faq, then get him to re-do the idle & co as per the faq. Or just print it out and make him re-do the lot properly :lol:
     
  6. nickh89GTi Forum Member

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    Think i will take it back to him to do properly. Would everything being out be giving these problems mate.

    Thanks for your help mate. Hope this sorts it out as its really frustrating.

    Cheers Nick
     
  7. rubjonny

    rubjonny Administrator Staff Member Admin

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    well if he didnt put the ecu into setup mode before messing with the idle & co this will make it idle funny id expect, and the ign timing being out wont help either! Get it set up right first, then we can rule that out if the problem comes back!
     
  8. nickh89GTi Forum Member

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    Its weird because i don't remember it being this bad before he had it for an afternoon. Will get it sorted then get back. Hope this is causing it tho.

    Cheers Nick
     
  9. nickh89GTi Forum Member

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    Another thing was i tried setting the ign timing and then the idle but the idle screw went right in (wouldn't turn anymore) and it was at 1100 - 1200 rpm?

    What do i need to do so i can set the idle to 950?

    Cheers Nick
     
  10. rubjonny

    rubjonny Administrator Staff Member Admin

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    sounds to me like your throttle cable is too tight, or the throttle stop isnt adjusted properly. either that or you have an airleak somewhere!

    Make sure when the throttle is released it hits the stop on the front firmly. If not loosen the accellerator cable slightly. If that doesn't allow it to hit the stop, loosen the idle switch underneath, if its been adjusted too far in it will hold the throttle open! I managed this one on mine, but to be fair I 'adjusted' my throttle switch bracket with a few light taps with hammer & drift as I had no way of getting to the bolts at the time :lol:
    Also worth getting a new throttle screw, dirt cheap from VW!

    If the throttle is definitly hitting the stop ok, have a good look at all your vacuum hoses, dont forget the one round the back of the throttle body, plus the 2 on the brake servo pipe, and the big yellow blanking cap on the brake servo pipe too. Check all 6 of your inlet manifold bolts are tight, bit of an **** as they're allen bolts and are hidden deep between the 2 manifolds!

    If all of that checks out, and only after you are sure everything is a-ok, adjust the throttle stop. The haynes procedure is as follows:
    1. Back off the adjustment screw until a gap exists between the carrier lever and stop lever.
    2. Turn the adjustment screw until the two levers just make contact, then continue to turn a further half-turn. Tighten the locknut.

    [​IMG]
     
  11. nickh89GTi Forum Member

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    I replaced the vacuum hoses a couple of weeks ago. But the vac hose i brought has a larger internal diameter than the ones i removed. Would this cause a problem ie. more air can travel through the vac pipes?

    Cheers Nick
     
  12. rubjonny

    rubjonny Administrator Staff Member Admin

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    hmm possibly, but i'd be more worried about them not fitting the existing vacuum fittings properly and allowing an air leak! I get my stuff from VW, its good stuff. I've heard BMW stuff is good too, apparently its silicone IIRC?
     
  13. nickh89GTi Forum Member

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    They do slide on and off of the throttle body fittings and the FPR very easily as they have a 5mm I/D so may be causing air leaks where the smaller 3mm I/D vac hoses would form a tight seal around the fitting? [:s].

    This would only be causing a slight air leak although i suppose any amount of un-metered air will cause problems.

    What do you think?

    Cheers Nick
     
  14. rubjonny

    rubjonny Administrator Staff Member Admin

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    yeah you dont want your vac fittings to be loose, get some 3mm i/d stuff :thumbup:
     
  15. nickh89GTi Forum Member

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    Think i got some spare 3mm I/D lying around the garage. Will check the condition of it and give everything another go.

    Hope this solves the problem.

    Cheers for your help, will post my findings later.

    Nick
     
  16. nickh89GTi Forum Member

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    Hey rubjonny,


    Been out and changed my vac lines and went for a drive to get up to temp. Got home switched engine off then on again and problem solved. [:D]

    Guess the 5mm i/d vac lines were getting warm and expanding allowing air leaks.

    One thing i did notice was that when coming up to a junction and dipping the clutch the revs would drop to about 400-500rpm. Is this just the idle needs setting up again?

    Cheers for your help chap. :thumbup:

    Nick
     
  17. rubjonny

    rubjonny Administrator Staff Member Admin

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    could be if you're sure the idle switch is pukka!
     
  18. nickh89GTi Forum Member

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    Yea i'm pretty sure the idle switch is pukka as its the third one i have put on. :lol:

    I'm hoping it just needs the idle and CO set up and also will re-check the ignition timing just to be sure its spot on.
     
  19. nickh89GTi Forum Member

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    Hi Guys,

    Just when i thought i had solved my idle problem it has come back.

    The idle is now sticking at about 2k rpm even when it is started from cold. When it doesn't do it i know have a nice solid idle at 950rpm (was lumpy before).

    I have had to change the main pump recently as the plastic housing had developed a nice leak. I have also changed the ISV and inlet boot for know good items, and i also had the vacuum lines on the front of the throttle body the wrong way round.

    Should i now invest in a new blue temp sensor from VW or is the problem being caused by something else?

    Thanks in advance for any help guys.

    Nick
     
  20. rubjonny

    rubjonny Administrator Staff Member Admin

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    i would buy a new blue sender either way, its always the 1st thing I change on these cars. is the idle screw still wound all the way in?
     

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