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Emission Control warning Light, erratic idle speed = my car doesn't like motorways!

Discussion in 'Audi S4/A4/A4 Cab (B7 Chassis)' started by mancdan, Oct 16, 2012.

  1. mancdan
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    mancdan Member

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    I keep getting a problem whenever my car has been on a Motorway/dual carriageway run.

    I recently went from Manchester to Glasgow for the weekend and upon returning back to Manchester the Emission Control Warning light came on when I exited the Motorway after approx 4 hours driving.
    The light stayed on for 2 days and then went off. This was 2 weeks ago.

    The light has now come back on and been on for approx 48 hours and I haven't done any long driving runs.

    The other problem I have is erratic idle speed again every time I go on a motorway run, even if its just for a couple of miles.
    When I exit the motorway and come to a stop, the idle speed varies between 1000 and as much as 1400 rpm sometimes, it sounds like my car is revving its tits off!
    The only way I can bring it down is to gently let the clutch out a bit, but as soon as I depress the clutch again the idle speed begins to creep up. Its so annoying that I now hate it every time I use a Motorway or similar type of road.

    I have had the Coil pack recall done plus recent Cambelt & water pump change, but the erratic idle speed was present before these were done anyway.
    Anyone have any ideas what the problems could be? Could they be linked?

    Thanks, Dan.
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  2. mancdan
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    mancdan Member

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    Emission Control Light now gone off again!

    Could the ECU be temperamental/faulty and does anyone know approx cost to replace the ECU?
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  3. solaris
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    solaris Member

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    Could be the PCV valve, a scan would confirm this..more info here
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  4. mancdan
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    mancdan Member

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    Thanks Solaris, this sounds just like my problem as I have noticed MPG has gone worse too.
    Can you remember the price of the PCV Valve and is that the Audi Part Number (part number 06F129101N)?

    Cheers, Dan.
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  5. olethalb
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    olethalb Member

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    mine does the same ocasionally, just fitted BSH PCV fix plate but still does it. seems to be an issue with a split pipe to my carbon cannister.

    As Solaris says though PCV is first port of call
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  6. mancdan
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    mancdan Member

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    Any idea on approx cost of PCV Valve and Gasket?
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  7. olethalb
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    olethalb Member

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    i bought a plate that gets rid of the PCV part completely, turns out my PCV was fine anyway (recently replaced) by precvious owner.

    sorry can't say how much a new PCV is
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  8. mancdan
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    mancdan Member

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    How much was the plate you bought then olethalb?
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  9. olethalb
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    olethalb Member

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  10. mancdan
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    mancdan Member

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    OK, PCV and gasket successfully changed last Friday. Took me about 15 mins once I got the correct tools!
    Part Numbers & prices were as follows: PCV at £37 = 06F 129 101N and Gasket at £18.40 = 06F 103 483E

    BUT, still got the erratic idle issues and the Emission Control Warning light has come on again :wtf:

    Is it time to get someone with VCDS to plug it in??
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  11. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep

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    i cant belive ppl still change parts when hey havent had a scan for codes
    its a waste of time and money
    it could be a split pipe or even the MAF
    unplug the maf see how it runs.
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  12. mancdan
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    mancdan Member

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    I did think that bez but read somewhere that changing the PCV valve after 50k miles was a good idea anyway, but lesson learned!
    Where abouts is the MAF?
    (By the way, was it you I came to in Sheffield to clear my airbag light when I changed the wiring under the seat?)
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  13. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep

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    iv done a few infact loads
    so yeah could have been
    across from the pub an carwash ?
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  14. mancdan
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    mancdan Member

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    I think so, on the main road with tram lines?
    Rough idea as to where the MAF is so I can unplug??
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  15. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep

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    yeah thats me
    the maf is on the left as your looking under the bonnet on the pipe going to the airbox
    put a pic up ill point it out.
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  16. mancdan
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    mancdan Member

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    Here you go Bez, hope picture is close enough.

    A4 Engine bay.jpg
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  17. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep

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    remove the big airpipe
    and you will se eit under there
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  18. mancdan
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    Should the MAF just unclip and pull out or do I need to remove those security torx screws?
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  19. mancdan
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    mancdan Member

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    Unplugged what I thought was the MAF (part no. 06F 906 461A) and ESP light has come on!
    Have I unplugged wrong part?
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  20. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep

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    the MAF may send a light on
    there is 2 security screws holding it to the tube
    when u get a new maf its already in that tube
    to clean it u need to remove them i have a use 1 with around 1k miles on it
    take a pic with thebig air pipe off ill point it out
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  21. mancdan
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    mancdan Member

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    I didn't need to remove air pipe to unplug the MAF so will need to remove it and then take a pic for you.
    Let me know how much you want for your used one too.
    Cheers.
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  22. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep

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    (it was the MAF you unplugged)
    how did it drive when you unplugged it
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  23. mancdan
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    Haven't drove it yet but am about to leave work so will know in the next few mins and report back later!
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  24. ANDYTQ
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    Mine idles too fast when cold so changed pcv anyway its done 88,000 so probably past its best,i would like to give the valves a clean next and change fuel pump follower at the same time.
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  25. mancdan
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    Well, unplugging MAF didn't alter the erratic idle as it appeared again this morning whilst in traffic and I had only driven on A/B roads, max speed 35mph and done approx 6 miles. Also the Emission Control warning light came on again.
    I have now plugged the MAF back in again and ESP light has gone out but ECW light has stayed on.

    This is a video of the erratic idle whilst at some traffic lights this morning. You can see that I revved it a little at 8 seconds to see if it would go back to normal and it didn't.
    I also let the clutch out a bit at 22 & 46 seconds to get the idle down, but as soon as I depress the clutch back in, the idle speed goes back up again.

    Its driving me fckin mad now and I'm thinking it really needs to go on VCDS.

    [video]http://s6.beta.photobucket.com/user/dti2k/media/ErraticIdle.mp4.html[/video]
    Last edited: Oct 26, 2012
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  26. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep

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    if your around my way again ill scan it you
    see if the problem is stored
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  27. mancdan
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    mancdan Member

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    Cheers Bez, I'm never usually around Sheffield but would make a special trip there just to get it scanned as its really bugging me!
    When is a good time/day for you?
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  28. bez101
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    bez101 Yorkshire & Humber Rep. Regional Rep

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    sunday after 5pm
    or day next week after 7pm
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  29. mancdan
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    Cheers mate, I will let you know.
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  30. mancdan
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    mancdan Member

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    This issue has now been fixed by Rick & Spencer at Unicorn Motor Developments in Stockport.

    It turned out to be the N80 Valve and so far the idle speed is perfect and car runs a lot better too.
    Cost of new part approx £25 plus an hours labour to fit.

    I would like to give a big shout out to both these guys as they are very thorough and have a great wealth of knowledge.
    I would have no hesitation in recommending their services.

    Now to save some pennies for one of Rick's customer remaps!
    #30

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