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Cold Start Idle problem (With Video)

Discussion in 'A3/S3 Forum (8L Chassis)' started by Westy, Feb 3, 2010.

  1. Westy

    Westy Well-Known Member

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    Guys please take a look at the vid below of my S3 rev needle bouncing about first thin in the morning. The car has only started soing this over the last 2 months and once the needle has settled its fine.


    suggestions as to what might be causing this and any ideas on how I can check.

    Could the temp sensor be causing the problem?

    Also does anyone know how to embed a sodding photobucket video??? It's driving me mad!
     
    #1 Westy, Feb 3, 2010
    Last edited: Feb 3, 2010
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  3. Welly

    Welly VX220 SC Driver :)

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    Wow! Thats impressive stuff dude! Nice 25.1 MPG average I see as well....lol :)

    Have you checked for any vac leaks? And anything coming up on VAG COM? It's odd that it almost stalls, and then behaves.
     
  4. Westy

    Westy Well-Known Member

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    I'd only just filled up and reset my DIS then driven back from the petrol station the night before :)

    Nothing on VCDS and no visible splits in pipes.

    I have noticed this since doing the n249 removal but it only does it when stone cold, first thing in the morning. Apart from this the car seems to be behaving fine!
     
  5. Welly

    Welly VX220 SC Driver :)

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    Hmmmm. Whats your engine code?
     
  6. Westy

    Westy Well-Known Member

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    BAM
     
  7. Welly

    Welly VX220 SC Driver :)

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    Arse. Didn't know if it was an APY - thought it might be the SAI system playing up, but the BAM doesn't have it. :(

    Is the N249 valve still electrically connected? If so, try disconnecting it (I got fed up with mine being there so just removed it totally and left the plug hanging - sod the engine management) just for testing purposes. It won't hurt.
     
  8. Westy

    Westy Well-Known Member

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    Good plan mate, I'll disconnect it tonight and see how it is in the morning. If its ok disconnected I'll solder in the resistor to make the management light go away.
     
  9. Westy

    Westy Well-Known Member

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    Ok, I unplugged the N249 valve and tried again this morning and it was even worse! The car dropped to about 200 revs and I have no idea how it didn't stall!

    Video is here:

     
  10. Welly

    Welly VX220 SC Driver :)

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    Hmmmm, OK. So unplugging the N249 wasn't the most successful test! :(

    My question is that why, when you unplug it, does it make it so much worse. On that video it looked like she was idling like a scatty crack whore..... Then was fine once settled down. You said this only started when you removed the vac chamber etc?
     
  11. Westy

    Westy Well-Known Member

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    I only noticed this problem after doing the N249 bypass but put it down to coincidence. Unplugging the wiring from the valve didn't throw up a light on the DIS either but may have done on VAGCOM, I'll check that later.

    It's only the initial start up then once its stopped spazzing out it idles fine! Does anyone know what the N249 valve is doing during the startup cycle?

    Welly (or anyone else who has done the N249 bypass) can you try unplugging the valve and see what happens for you.
     
  12. Welly

    Welly VX220 SC Driver :)

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    Mine is unplugged dude, and has been for weeks. Reason being that I had all these coil issues and couldn't be arsed to keep taking the bracket off all the time!

    I, like you, don't get a DIS warning, or EML, but there is a fault code logged for the lack of N249.

    But, back to the point, no cold start issues.
     
  13. Westy

    Westy Well-Known Member

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    That's interesting! Could it be possible that the map on my car requires the N249 for startup?
     
  14. Welly

    Welly VX220 SC Driver :)

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    Possible, but I would think unlikely. Out of my depth of knowledge... I have PM'd Badger5 the link to this thread, hopefully he can say more definitively...
     
  15. Westy

    Westy Well-Known Member

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    Found this PDF that explains what the N249 does if anyone wants a bit of light reading:

    http://shaw-clan.com/beetlepix/N249cutaway.pdf

    The diagram of how the N249 is plumbed in looks different to the S3. I'm sure we dont have the hose that connects to the N75 valve!?
     
    #14 Westy, Feb 4, 2010
    Last edited: Feb 4, 2010
  16. Welly

    Welly VX220 SC Driver :)

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    No, we don't.... It connects to the DV instead. Same basic principle I guess though, a method of boost control. Instead of realeasing boost through the DV, it opens the wastegate.
     
  17. Westy

    Westy Well-Known Member

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    If I get time this weekend i'll put all my N249 gubbins back on the car and see if my cold start issue goes away.
     
  18. Welly

    Welly VX220 SC Driver :)

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    I think that's the only belt and braces test you can do really to be fair. I'll be interested to see results, never heard of that before!!
     
  19. Westy

    Westy Well-Known Member

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    If it does fix the problem then we'll be stumped!

    I'll do another VCDS power run too because when I removed the N249 I got an extra 2 psi but lost 10bhp!
     
  20. Welly

    Welly VX220 SC Driver :)

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    Lost 10 BHP? Huh? Where did you put it Westle? Huh? Did you hide it? :)

    Thats strange, although atmospheric conditions mightn't of helped. Its one of those 'needs to be done on the same day' tests really.
     
  21. Westy

    Westy Well-Known Member

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    I'll do a before and after, same day test on sunday then. My guess was that because the N249 wasn't there to open the DV mid throttle that's why I was getting the extra PSI but the ECU was retarding the timing due to the extra boost! I was hoping that a silicone TIP and FMIC would bring the timing back in line, but I wont find that out till next month ;)
     
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  23. Welly

    Welly VX220 SC Driver :)

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    Oooooh I can't WAIT to fit my FMIC this weekend.... If the jubilee clips arrive that is. 3" pipework needs 70 - 90 mm clips. Try finding those at Focus....
     
  24. Westy

    Westy Well-Known Member

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    You should have just bought some guttering from focus and fitted that!
     
  25. Welly

    Welly VX220 SC Driver :)

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    Hmmmmm.... Not sure how well it would react to being hit by a stone at a ton.... But meh. Cheap and cheerful!
     
  26. Sandip

    Sandip Well-Known Member

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    Westle you may have already done and tried this but have you cleaned your throttle?

    Another thing you could try before anything major, just put your ignition on, leave it for a couple of minutes and let the after run pump go for a bit then start it, see if it's any different.

    No harm in trying, if you have already then ignore this post lol
     
  27. Westy

    Westy Well-Known Member

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    Thanks for you suggestions Sadip, I'm after anything at the moment. I always let my fuel pump prime before firing the enine but I'll leave it a bit longer tomorrow morning. I haven't had my TB cleaned yet but I think i'm onto something with the N249 valve as its not behaving correctly, so I'm going to do down the route of replacing the vac chamber first before I try a TB clean. cheers
     
  28. Welly

    Welly VX220 SC Driver :)

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    I'd be inclined to agree, especially when disconnecting the N249 made it much worse! Still, a clean TB is a happy TB. I wet and dry'd mine, then polished it for good measure!

    http://s591.photobucket.com/albums/ss354/welly1986/?albumview=slideshow

    This is the one off of my old AGU - but the S3's is just as gleaming! Well, was. :(
     
  29. Sandip

    Sandip Well-Known Member

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    It's not the fuel pump Westle, it's the secondary waterpump, when i had a similar thing happen to mine, it started a little better after letting it run for a while.
    If you can get hold of some vac pipe you could bypass the n249 totally, this will rule it out for definite, its not a big job to do, take 5-10mins
     
  30. Westy

    Westy Well-Known Member

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    I thought I had bypassed the N259 by ripping all the vac chamber and stuff off! What do you mean?
     
  31. Sandip

    Sandip Well-Known Member

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    When the n249 consists of a vac pipe from the dv to the intake manifold

    Basically disconnect the vac pipe what is under the intake manifold on the left hand side, then run a vac pipe directly form here to the dv, done!

    Bit of a **** image but hopefully it helps you bud, the connection is under the black dot under the Intake manifold

    [​IMG]
     
  32. Westy

    Westy Well-Known Member

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    Thats what i've done mate. The N249 vavle is just connected electonically!
     
  33. Sandip

    Sandip Well-Known Member

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    ok cool, so it ain't the n249 then:) try my other plan though lol
     
  34. Westy

    Westy Well-Known Member

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    What I said was I only started to get this problem when I bypassed the N249. This morning I tried a cold start of the car but with the N249 electronically disconnected and the problem got worse. This weekend I will put all the vac chamber back on and see if my problem goes. If it does then I dont have a clue why its causing the problem!!!
     
  35. Westy

    Westy Well-Known Member

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    I started up this morning with a slight stutter but not as bad as yesterday.
     
  36. Westy

    Westy Well-Known Member

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    I think the N249 valve was a red herring because I am now getting the really poor cold startup issues as seen in the 2nd vid above. Vagcom isn't showing any errors but I'm going to replace the temp sensor.
     
  37. Welly

    Welly VX220 SC Driver :)

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    Thats weird dude! As the OMC said, how bizzare....
     
  38. Westy

    Westy Well-Known Member

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    Ok I swapped my temp sensor last night and started this morning. Still the same!

    Te temp sensor I took out wasn't an original one so it has been changed before.

    Tomorrow morning i'm going to unplug the MAF and start it up to see if its any better.
     
  39. Welly

    Welly VX220 SC Driver :)

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    Process of elimination..... lol. It's definately something electrical spazzing out.
     
  40. Westy

    Westy Well-Known Member

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    Yeah it's definitely getting worse each day too! The temp sensor was a nice waste of £33, I think I'll test the mad before just going to buy one :)
     
  41. Welly

    Welly VX220 SC Driver :)

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    Yeah, now that sounds like a good shout!!
     
  42. Westy

    Westy Well-Known Member

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