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Cleaned IAC, now stalls on every start.

Discussion in 'VR - VS Holden Commodore (1993 - 1997)' started by CRCinAU, Oct 9, 2012.

  1. CRCinAU

    CRCinAU New Member

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    Hi all,

    Originally (ie what caused me to clean the IAC) was that even taking your foot off the accelerator would stall the engine (fun at 80kph!). So I cleaned the IAC and now when it idles, it is very smooth.

    I used the howto on this site:
    http://forums.justcommodores.com.au...313-vn-vr-iac-idle-air-control-how-clean.html

    I've posted pics of the 'dodge' I had to do as the blasted screw snapped off (which is apparently common).

    So - now that I've put it all back together, I've noticed that every time I start the car (hot or cold), the engine stalls. If I give it a bit of a squirt on the accelerator while cranking, it jumps into life and idles fine. It runs fine, idles fine while stopped at intersections etc...

    I've hooked up EFI Live to the car and can see the IAC steps changing when the engine is reved and going back to idle. The mixture is good according to the O2 sensor. I also reset the IAC and LTFC using EFI Live after cleaning both the throttle body and the IAC.

    This leaves me at a bit of a loss. The only thing I can think is that the IAC is not opening up enough for the start? Any thoughts on this? Any signs to look for on EFI Live?
     
  2. GTP 85

    GTP 85 291 hp @ the wheels

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    Have u reset the iac? rev it in neutral up to approx 3k and let the revs come down on its own. Usually it will stall first time. Do it again, and the iac steps should reset
     
  3. CRCinAU

    CRCinAU New Member

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    I haven't done that... What do you mean by let it come down on its own? If its in neutral, then holding the accelerator at 3000rpm will keep it at 3000rpm?
     
  4. James39

    James39 Gave up on VL's

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    Which means remove your foot from the pedal once you have reached 3000 RPM.
     
  5. CRCinAU

    CRCinAU New Member

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    Righteo :)

    I wasn't too sure if you started it and straight away held 3000rpm that the ECU would back it back down to idle until the throttle was reset and used again. I've driven the car normally for about 100km - but it still stalls on every start. I'll try holding it at 3000rpm for a little while on start and see what happens....
     
  6. NickVR

    NickVR Active Member

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    What Gilbs said is right to reset it. Best to start again from scratch.

    1 Disconnect the battery (about 10mins should do)
    2 Reconnect when time has passed.
    3 Start the car and instantly rev the car to 3k or around that doesn't need to be exact. (hold throttle down a bit when starting if you want)
    4 Hold it there until you hear the car change the revs by itself.
    5 Keep your foot steady until it's finished and the revs are maintained.
    6 Release the accelerator
    7 Then put your foot on the brake and put it into reverse. Let it learn the idle (a few seconds should do it)
    8 Then with your foot still on the brake put it into drive. Let it learn the idle (a few seconds should do it)
    9 Shift back into park.
    10 Then put the A/C on. Let it learn the idle (a few seconds should do it)

    This will complete the idle relearn procedure. Steps 7-10 can be done when you drive it next but I do it straight away because sometimes it won't learn during a drive.
     
  7. FXST01

    FXST01 The Grey Man

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    When installing the IAC valve, ensure that pintle is less than 28 mm from the body. (the screw in tabs)
     
  8. aussie4life11

    aussie4life11 Keep It Simple Stupid

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    Would this be the same for a 94 vr v6 series 2 acclaim?
     
  9. yxyx64

    yxyx64 New Member

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    not sure what you mean by good but o2 not used at idle in vr. o2 should show high voltage at idle.

    maybe clean iac again if above ideas did not fix as all this love may have dislodged some junk near iac .........
     
  10. NickVR

    NickVR Active Member

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    I was told so but never tried it on a V6. I do it every time my car get a flat battery because it won't idle otherwise. But mine is a V8.
     
  11. aussie4life11

    aussie4life11 Keep It Simple Stupid

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    Well i have been having problems with my idle for some time now and it also surges. Could this be because the baseline wasnt set properly?
     
  12. NickVR

    NickVR Active Member

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    It is possible. Costs nothing to try.
     
  13. soslowbro

    soslowbro New Member

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    Absolutely. Follow NickVR's how to mate. I tried it today and I dare say it's fixed the issues I was having.
     
  14. The1

    The1 A Memcal a Day Keeps..

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    The way above is nearly right, no need to rev or anything,

    Remove Battery Connection and leave a for a few minutes to reset PCM
    Reinstall battery connection
    start car and leave it run for 5seconds then turn it off

    Done

    Or a tech1 scantool can be used to issue a reset command.
     
  15. NickVR

    NickVR Active Member

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    Mine won't idle if you let it do it by itself. Everytime my battery dies (car isn't used that often) I follow what I wrote down and it has no issue every start after that. If I don't rev it, it will stall every start and I will have to use throttle to start it. You don't have to rev to 3k though I think 2k is high enough anything over is fine too. I was told to do it like this by a mate of mine who is mechanic and is great with commodores and all their issues.
     
  16. The1

    The1 A Memcal a Day Keeps..

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    When the pcm runs after a reset the IAC is just remapping it's step limit 0-255 by going fully in and fully extended. The pcm learns alot of other things on first startup, by reving on first startup you would be just masking a problem. I would reset the correct way and let it stall with a Tech1 connected, it can retrieve stall data and see what all the sensors were doing and there readings at the time of stall and look for the cause.

    Here's a scan in.

    [​IMG]
    [​IMG]
     
  17. NickVR

    NickVR Active Member

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    I am getting the car tuned soon as it has a cam in it and that may be the issue. Might try that procedure and see if it works too. Never know. Cheers for the info.
     
  18. The1

    The1 A Memcal a Day Keeps..

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    arh yep with a cam prob need slightly higher idle, then recheck and adjust throttlebody to get IAC at correct steps around 30. But that should all get fixed up with the tune :D
     
  19. NickVR

    NickVR Active Member

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    The throttle was done by the mechanic. But may need to be done again once tuned. Although it idles fine once I do that procedure (no higher than stock) but if I don"t do it, it stalls and doesn't what to do. Never had an issue with the V6 in it but that was stock, lol.
     
  20. aussie4life11

    aussie4life11 Keep It Simple Stupid

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    when i have had my iac out to clean it, i wasnt able to "push the pintle in" but it did screw in and out. is this normal or is it a stuffed iac?
     

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