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high idle speed s4

Discussion in 'A4/S4 forum(B5 Chassis)' started by Tuffty, Oct 16, 2010.

  1. Tuffty
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    Tuffty Member

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    [Oct 16, 2010]
    my s4 has randomly started idling at 1100 - 1200 rpm
    i've checked all the hoses i can get to for leaks, the recerc valves are seating nicely,
    i've cleaned the throttle flap and reset it.
    the only fault codes i'm getting are the EGT sensors (supprise supprise lol ) and an intermitant lambda heating fault.
    the car idles smoothly drives ok, although you can feel a slight surging at very light throttle.

    any thoughts?
    #1
  2. SonicDeathmonkey
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    SonicDeathmonkey Member

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    [Oct 16, 2010]
    Mine did exactly the same until I had the EGTs sorted, except it would also hessitate at about 3,000 rpm before kicing off again. Weird.
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  3. SonicDeathmonkey
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    SonicDeathmonkey Member

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    [Oct 16, 2010]
    bye the way, how does the 84 GTE turbo go? I used to have a J plate GSi Red Top. When I went to pick up my brand new Fiat Coupe turbo in '99, the woman at the fiat dealer asked me if "I made it myself". I didn't know what to say to her...
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  4. Tuffty
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    Tuffty Member

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    [Oct 16, 2010]
    mine does sometimes hesitate which i put down to the EGT's but it's idled fine up until now which is what i find odd.

    The astra's just shy of 290bhp, so makes the S4 seem very tame lol
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  5. evilscotsman
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    evilscotsman Space Cowboy

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    [Oct 17, 2010]
    cts?
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  6. Tuffty
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    Tuffty Member

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    [Oct 17, 2010]
    Think that'll be my next port of call, started it today from cold and the idle dropped down to normal after a min or so, but after driving it was back up to 1200.
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  7. SonicDeathmonkey
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    SonicDeathmonkey Member

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    [Oct 17, 2010]
    Doh, I should have said that I changes the CTS at the same time!!!
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  8. mwarrey
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    mwarrey Member

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    [Oct 17, 2010]
    What's CTS? I have the same issue on mine
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  9. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Oct 17, 2010]
    Coolant Temp Sensor.

    Easy to check with vagcom before condemning it though.

    Does your coolant guage behave? it should quickly climb to 90 in about 5-10mins and stay there resolutely.
    #9
  10. Tuffty
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    Tuffty Member

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    [Oct 18, 2010]
    changed the cts, no joy, looks like i'm gunner have to put my hands in my pockets for some new egt sensors and hope that solves it.
    #10
  11. evilscotsman
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    evilscotsman Space Cowboy

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    [Oct 18, 2010]
    a log of vag com for various values might provide a picture mate before you spend any more cash, a cheap lead and a run using the laptop then post the graphs, fuelling, boost, maf, temps, etc etc its all in there :)
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  12. Tuffty
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    Tuffty Member

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    [Oct 18, 2010]
    have the free version of vag com but my laptop battery died a long time ago so it needs permanent 240v lol, what should the maf read under load on an s4?
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  13. evilscotsman
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    evilscotsman Space Cowboy

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    [Oct 19, 2010]
    240v inverter plugged into the fag lighter - thats what im using, laptop wont run more than a minute off the mains lol
    #13
  14. Tuffty
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    Tuffty Member

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    [Oct 23, 2010]
    chucked a couple of Exhaust temp sensors on and she's still idling high. tried with the maf unpluged and she coughs and splutters but idles lower.
    bring back carbs! lol
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  15. evilscotsman
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    evilscotsman Space Cowboy

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    [Oct 23, 2010]
    tps calibration maybe work?

    Asda selling a 80W inverter that plugs into the fag lighter, £15 and it'll run yer laptop in the car for ever...
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  16. Tuffty
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    Tuffty Member

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    [Oct 23, 2010]
    have tried reseting the tps. will run off some logs tomorrow, at least the fault codes are clear now lol
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  17. Tuffty
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    Tuffty Member

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    [Oct 24, 2010]
    think i've found the problem, looking at the logs the bank 2 lambda is basicly shagged and not doing anything.
    Why do I get the feeling that bank 2 is the passenger side one which a complete sod to get to lol.
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  18. evilscotsman
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    evilscotsman Space Cowboy

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    [Oct 24, 2010]
    haha yeah it probably is mate :)

    Good find. Likely its preventing closed loop mode operation eh.
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  19. Tuffty
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    Tuffty Member

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    [Nov 2, 2010]
    lambda now fixed, still not idling right.
    think it's gunner catch fire soon !
    #19
  20. Tuffty
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    Tuffty Member

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    [Nov 8, 2010]
    Have now sorted it.
    turned out that the throttle flap had come out of alignment, and the foot on the throttle with the ignition on then off doesn't work on the S4, a quick reset on vag-com and job jobbed. :beerchug:

    Ross-Tech: VAG-COM: Throttle Body Alignment
    #20
  21. S4twiggy
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    S4twiggy Fully Certified Detailer!!

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    [Nov 8, 2010]
    if you leave the ignition on for about 30 seconds ive been told the TB resets itself
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  22. Tuffty
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    Tuffty Member

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    [Nov 9, 2010]
    Doing that only sets the max open and shut of the flap. Not the idle / overun etc positions
    #22
  23. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Nov 9, 2010]
    TBH i cant believe that.

    Seems completely stupid to design an ECU that every time the battery was removed the car NEEDS to be plugged into a dealer computer to reset the throttle body. Given the throttle position is a safety critical component, there MUST be an automatic alignment system built in.

    Did you actually try just turning the ignition on without touching any of the pedals and leaving the car for a minute or two to do its thing?
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  24. Tuffty
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    [Nov 9, 2010]
    Trust me I've spent 3 weeks searching for an answer to this. I've tried with and without moving the throttle and various lengths of time with the ign on and off. Ive even left the battery off overnight to try and get it to reset. But the vag-com way was they only thing that worked.
    #24
  25. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Nov 9, 2010]
    Fair enough. Maybe yours was extra-stuck or something :p
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