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Hesitation/Misfire problem

Discussion in 'A3/S3 Forum (8L Chassis)' started by RichA3Turbo, Jan 20, 2006.

  1. RichA3Turbo
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    RichA3Turbo ...Watching you! Staff Member Moderator

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    Well i've checked the temp on the gauge, and on the climate control, and they are more or less the same which tells me the temp sensor is OK.

    Thanks for the advice though - i will consider it if it still doesnt start.

    Rich
    #81
  2. madvw
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    madvw Active Member

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    the climate one would give you the figure you need. From my experiences on my corrado i found there to be 2 temperature sensors - one for the ECU and one for the Dash guage.
    #82
  3. RichA3Turbo
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    RichA3Turbo ...Watching you! Staff Member Moderator

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    [ QUOTE ]
    the climate one would give you the figure you need. From my experiences on my corrado i found there to be 2 temperature sensors - one for the ECU and one for the Dash guage.

    [/ QUOTE ]

    Correct - Both of which appear to be OK.

    Rich
    #83
  4. god_thats_quick
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    god_thats_quick Numptie of the highest order

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    What normal temps do other S3 owners get on the climate control jobbie, mine seems to hover between 94-96 when up to temp?
    #84
  5. RichA3Turbo
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    RichA3Turbo ...Watching you! Staff Member Moderator

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    My 'stat is screwed, so only gets upto about 76!
    #85
  6. HTC
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    HTC Active Member

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    Gauge should sit at bang on 90 all the time on s3 and a3. Anything else and I'd start looking at the cooling system and sensors.

    Me buddies S3 had the sometime will start, sometimes won't and horrible cold running probs as well.

    A new coolant sensor fixed it, but interstingly his dash and aircon temps were reading fine.

    Same issue with my golf. Gonna be swapping the sender on monday.

    Not looked at the wiring diagrams, but there are 4 pins. Maybe only half the sensor fails?? /ubbthreads/images/graemlins/confused.gif
    #86
  7. god_thats_quick
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    god_thats_quick Numptie of the highest order

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    [ QUOTE ]
    Gauge should sit at bang on 90 all the time on s3 and a3. Anything else and I'd start looking at the cooling system and sensors.

    Me buddies S3 had the sometime will start, sometimes won't and horrible cold running probs as well.

    A new coolant sensor fixed it, but interstingly his dash and aircon temps were reading fine.

    Same issue with my golf. Gonna be swapping the sender on monday.

    Not looked at the wiring diagrams, but there are 4 pins. Maybe only half the sensor fails?? /ubbthreads/images/graemlins/confused.gif

    [/ QUOTE ]

    When you say that the gauge should site at 90 all the time do you mean the digital readout on the climate too, as I can't believe it can always be exactely 90, if some others with S3s could like me know what the climate thingy shows for temp (49 on the climate thingy) once up to temp after a few miles etc that'd be good.
    #87
  8. Khufu
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    Khufu Active Member

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    IIRC my brother who works for SAAB says the one you see is like an average temp, hence it stays at about 90 degrees even though in reality it is actually altering depending on engine load. The digital readout will be more acurate.
    #88
  9. HTC
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    [ QUOTE ]
    [ QUOTE ]
    Gauge should sit at bang on 90 all the time on s3 and a3. Anything else and I'd start looking at the cooling system and sensors.

    Me buddies S3 had the sometime will start, sometimes won't and horrible cold running probs as well.

    A new coolant sensor fixed it, but interstingly his dash and aircon temps were reading fine.

    Same issue with my golf. Gonna be swapping the sender on monday.

    Not looked at the wiring diagrams, but there are 4 pins. Maybe only half the sensor fails?? /ubbthreads/images/graemlins/confused.gif

    [/ QUOTE ]

    When you say that the gauge should site at 90 all the time do you mean the digital readout on the climate too, as I can't believe it can always be exactely 90, if some others with S3s could like me know what the climate thingy shows for temp (49 on the climate thingy) once up to temp after a few miles etc that'd be good.

    [/ QUOTE ]

    Sorry dude, me reading to quickly. thought you talking about dash gauge.

    I'll get me coat.

    Still, weird that the temp sensor can fail but the gauge work. I'll have to look at some diagrams.
    #89
  10. Markb
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    Markb Active Member

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    So Rich any progress on the cause of the problem?
    #90
  11. RichA3Turbo
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    RichA3Turbo ...Watching you! Staff Member Moderator

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    [ QUOTE ]
    So Rich any progress on the cause of the problem?

    [/ QUOTE ]

    Will let you know tomorrow!!
    #91
  12. RichA3Turbo
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    RichA3Turbo ...Watching you! Staff Member Moderator

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    Right guys, I've had an interesting day!

    I set out this morning, and soldered all my Racelogic connection and heatshrunk them all - They are now proper permanent connections. This took me bloody ages to do as for the awkwardness of it!

    Once i had done, i crossed me fingers and started the car. No luck! Still only running on 3 cylinders. So i swapped the spark plugs and tried again...Still...Nothing!

    By this point i was getting rather p*ssed off with it! So next port of call was the coil packs. One by one, i disconnected the coil pack plugs and started the car. The first one i unplugged (cyl 4) made no difference, with all the others (Cyl 1,2,3) all making it run on 2 cylinders.... AHA! i thought - duff coilpack!

    So i touched the branh of the exhaust manifold for that cylinder and it was cold, where all the others were rather hot!

    I swapped Cyl4 with Cyl1 coilpack (after letting mani cool down) and repeated the process - Still cyl4 playing up!

    Still thinking coilpack?

    WRONG!

    I took the coilpack out (cyl4), and with a spare spark plug, put it in the coilpack, and grounded it and started the car - No spark!

    This pointed to a wiring fault, so i disconnected the plugs from the ECU and buzzed them all out continuity - nothing very little happened!

    Thats when i had a brainwave!

    On the earlier 1.8T, there is a spark generator or something - It sits on the airbox lid. The cilpack wiring goes from ECU>Spark Gen>Coilpack.

    I checked continuioty from coilpack to the spark gen - OK
    I checed continuity from spark gen to the ECU - OK

    FINALLY! I had found the culprit! I borrowed a spare one off of my mates Mk1 1.8T, and gave it a go. Started car and after a bot of a splutter, it was running perfectly on 4 clyinders!

    WOOHOO!!

    put mine back in and it ran on 3 again. Conclusive i think!!

    So, i'm now pretty certain that this has been the cause of my hesitation issues, and it finally gave up on Thursday evening.

    Its taken me the best part of 5 hours today to sort this god damn thing out!

    ETKA calls it a Control Unit Power Output Stage.

    Rich
    #92
  13. HTC
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    HTC Active Member

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    Good work detective Rich. Always a big relief when you find a definate cause and solution!
    #93
  14. RichA3Turbo
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    RichA3Turbo ...Watching you! Staff Member Moderator

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    Took bloody long enough! Was getting V V V p*ssed off with it!
    #94
  15. Markb
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    Markb Active Member

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    Great stuff!

    So what sort of price are these to replace?
    #95
  16. Khufu
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    Khufu Active Member

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    as said, the ends justifies the means LOL.Seriously, glad you gotta result.
    #96
  17. RichA3Turbo
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    RichA3Turbo ...Watching you! Staff Member Moderator

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    [ QUOTE ]
    Great stuff!

    So what sort of price are these to replace?

    [/ QUOTE ]

    I'm yet to figure that out - My mates golf was using a Hitachi version which doesnt appear in ETKA so going to have a look about - Im expecting though around £30

    Rich
    #97
  18. darnich
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    darnich Member

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    Good catch!
    Glad you've sorted it out!
    #98
  19. HTC
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    HTC Active Member

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    If its the "control unit power output stage" its fookin' expensive for what it is.

    part number 4D0 905 351 £222.19 inc vat!! /ubbthreads/images/graemlins/shocked.gif

    I'd heading down the breakers yard for that one.
    #99
  20. RichA3Turbo
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    RichA3Turbo ...Watching you! Staff Member Moderator

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    [ QUOTE ]
    If its the "control unit power output stage" its fookin' expensive for what it is.

    part number 4D0 905 351 £222.19 inc vat!! /ubbthreads/images/graemlins/shocked.gif

    I'd heading down the breakers yard for that one.

    [/ QUOTE ]

    Yep - was doing some research and found that /ubbthreads/images/graemlins/frown.gif bloody ripoff!!
  21. Ryanc
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    Ryanc Active Member

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    scrappy time.
  22. Drill
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    Drill Member

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    Any chance someone has a pic where I could see where this thing is?

    Thx /ubbthreads/images/graemlins/beerchug.gif
  23. HTC
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    HTC Active Member

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    Its quite easy to find. Its attached to the top part of the air filter box. It has two electrical plugs that are attached one either side.
  24. RichA3Turbo
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    RichA3Turbo ...Watching you! Staff Member Moderator

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    But its only on earlier models - If its DBW, then i dont think you will have it - i think its intergral part of the coilpacks.

    Rich
  25. AL_B
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    AL_B Active Member

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    Excellent stuff Rich. Well done mate.

    AL
  26. benk
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    benk Member

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    As you say, that little thing sits on top of the airbox and receives small electrical signals from the ECU. Those small signals effectively trigger the circuits to the coilpacks. Later cars don't have this box of tricks as the functionality was moved to become part of the coilpacks themselves.

    See here for some info on the Power Output Stage / Ignition Control Unit / Ignition Amplifier , (it has many names):

    http://forums.audiworld.com/a4/msgs/1594531.phtml
  27. RichA3Turbo
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    RichA3Turbo ...Watching you! Staff Member Moderator

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    Cheapest i've found so far is Murrays Direct which is £108+vat. MUCH better, but still looking. It hurts to pay so much for such a physically small part!!
  28. benk
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    benk Member

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    Perhaps, but remember that by having this part, you should be avoiding the coilpack problems that most people get with later models.

    Do Audi still replace people's coilpacks free of charge? If so then maybe you could try arguing that in the earlier models, the N122 is the problem, and not the coils, so will they help you with cost on the older part?

    In terms of Hitachi parts instead of the Bosch one, my mate's A4 also had the Hitachi part, but I didn't risk trying it in my A3 1.8T when I was testing my N122. When I read up up this, some people were saying they were equivalent, and swappable, but I wouldn't want to take the risk myself, and even less in your case when you've got enough other additions and tweaks in place.
  29. RichA3Turbo
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    RichA3Turbo ...Watching you! Staff Member Moderator

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    This is the same part that fails in coilpacks - But its not a common issue. Mines lasted 8 years and 75000 miles.

    I tried the Hitachi part, as the part number is identical apart from the prefix, which is purely down to it being a different manufacturer - it worked just fine.

    Rich
  30. AL_B
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    AL_B Active Member

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    RIch, guys,

    As said above, later model cars don't have this N122, and the output stage is combined into the coil pack.

    But what I don't understand is, if the output stage is combined in the coil packs, how does that affect earlier model cars (like yours Rich) that still have the N122? Presumably you are using version "J" or "L" coil packs?

    AL
  31. RichA3Turbo
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    RichA3Turbo ...Watching you! Staff Member Moderator

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    [ QUOTE ]
    RIch, guys,

    As said above, later model cars don't have this N122, and the output stage is combined into the coil pack.

    But what I don't understand is, if the output stage is combined in the coil packs, how does that affect earlier model cars (like yours Rich) that still have the N122? Presumably you are using version "J" or "L" coil packs?

    AL

    [/ QUOTE ]

    Al,

    my coilpacks are different to yours or cars which dont have the N122. Mine look similar to this:
    [​IMG]

    where your should look like this:
    [​IMG]

    Rich
  32. AL_B
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    AL_B Active Member

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    ahhhhhh, right. So you are using the older style coil packs. That explains things then.

    Bet Audi/VW wished they'd never changed the design now, after all the problems the newer style coil packs caused.

    AL
  33. RichA3Turbo
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    RichA3Turbo ...Watching you! Staff Member Moderator

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    Yep thats for sure - I cant complain really as this is the first bit of electrics that ahs failed since i've owned the car...other than the A/C compressor last week...D'oH!

    Rich
  34. benk
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    benk Member

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    Exactly my point - the old way seems more reliable to me, and I've only ever heard of about 2 or 3 people who had N122 failures.
    The point I was trying to make is that I'd rather have the N122 than coilpacks failing every now and then, but yes, the price of that tiny part is a kick in the nuts.
  35. RichA3Turbo
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    RichA3Turbo ...Watching you! Staff Member Moderator

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    [ QUOTE ]
    Exactly my point - the old way seems more reliable to me, and I've only ever heard of about 2 or 3 people who had N122 failures.
    The point I was trying to make is that I'd rather have the N122 than coilpacks failing every now and then, but yes, the price of that tiny part is a kick in the nuts.

    [/ QUOTE ]

    Yeah so would I - its costly, but less of a pain.

    Rich
  36. HTC
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    Have you tried any online breakers yet? I've had alot of success with them in the past.
  37. RichA3Turbo
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    RichA3Turbo ...Watching you! Staff Member Moderator

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    I've just bought a brand new one for £126 from murrays. Hopefully a new one will last longer than one thats come off a car of a similar age. Also need it ASAP!

    Rich
  38. RichA3Turbo
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    RichA3Turbo ...Watching you! Staff Member Moderator

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    Update:
    Car runs now OK...but still got the hesitation issue. Bugger!

    i've ordered coolant temp sensor and air temp sensor (in TB) and replacing thermostat on saturday. Is HAS to be one of them!

    Rich
  39. darnich
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    darnich Member

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    I wish you'll have it sorted soon!
    Good luck
  40. benk
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    benk Member

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    I think N249 was mentioned way back in this post - I couldn't be bothered to search back and find out, but this thread in the seatcupra.net forum mentions some stuff about behaviour of the N249 and that some people remove it:

    http://www.seatcupra.net/forums/showthread.php?t=42406

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