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Help - Coil Pack changed but still not running right!?!?...

Discussion in 'A3/S3 Forum (8L Chassis)' started by Jodi, Jan 2, 2006.

  1. Jodi
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    Jodi Starsky

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    Can anyone help me with the following please?

    A couple of weeks ago my S3 started to struggle at idle. Not seriously - but enough for me to have to rev a little higher to pull away smoothly on a hill. Over the next couple of days the car started to vibrate at idle. Not loads but enough to concern me (once moving it felt fine).

    Car went in for a Haldex oil and filter change (specialist not stealer). He also changed coolant temp sensor (VAGCOM indicated fault). He thought the car was missing on a cylinder.

    Next day I changed all four plugs. Noticed that on cylinder 4 (passenger side cylinder) the tip of the plug was covered in unburnt fuel. On firing the car up with new plugs the vibration was still there. So I then changed the coil pack on that cylinder.

    The car now seems to be running smoother, but still not perfect. It is definitely not running at full power and the exhaust sound is definitely different (almost a phut, phut, but not obviously so). Still struggles on a hill start.

    I'm stuck as the car does feel smoother, but not as it should, however I would be surprised if two packs were down originally as it was never that underpowered or lumpy.

    I have read other posts about the leads to the coil packs melting. Are the leads easy to replace?

    What else should I look for or what checks can I do to see what the cause is? VAGCOM had no other faults registered other than the temp sensor that has been changed.

    Could the MAF cause these symptoms? Any pipes I should check?
    Any help would be really appreciated as all I can see is loadsa money going to a garage to struggle to find the solution.

    Thanks guys.

    Jodi
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  2. Jodi
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    Jodi Starsky

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    Anyone.....please?
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  3. chippie
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    chippie Member

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    hi starsky.
    how many miles has the s3 coverd
    #3
  4. Jodi
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    Jodi Starsky

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    The car has done just over 57k.

    Looking in the archives people talk about cleaning throttle bodies or leaks in pipes, but I can't believe that either of these things would cause only cylinder 4's plug to be black with unburnt fuel.

    Any help really would be appreciated.
    #4
  5. HTC
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    HTC Active Member

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    THere was a guy on here recently that had an issue with some bad wires that run from the coil packs. I can't remember if it was the wires at the engine or round the back of the bay.
    Anyhow, the wires had rubbed on the plastic covering and worn through causing the missfire. If you checked everything else, I'd start tracing the wires.
    #5
  6. amb276s3
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    amb276s3 bird spotter

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    that was me, the wires in question came directly out of the top of the coil pack/s, if you look closely you can see 4 individual wires within the black insulation, the actual coloured insulation of these wires had started to melt away exposing the copper cores,these were either touching or just too close, causing a misfire/ loss of power above 3800rpm, the heat from the engine/turbo seems to make the coloured insulation brittle and that starts off a hairline crack which then leads to the melting/peeling back process. hope this helps.
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  7. Jodi
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    Jodi Starsky

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    Cheers guys. I shall take a look tonight with my cool new head torch. Any excuse to use a gadget. I will report back with what I find or not as the case may be. Until then.....
    #7
  8. Jodi
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    Jodi Starsky

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    Had a look at the wires into the coil pack and there is a split in the brown wire (labelled no.2 on the connector) and the beginnings of a split in the blue/red wire (labelled no.1 on the connector). I do have pics, but not sure how to post them and it's getting late. Tried to cover each wire individually with electrical tape and refitted to coil pack. Started her up, but not sure it's changed anything. Still feels lumpy to me.

    What did you do to fix your problem? It seems slightly different in that you were misfiring as you hit a certain rev range where as mine feels lumpy at idle, but not so bad once I'm up and running (underpowered though).

    Is it easy to replace the leads? I couldn't see where that part of loom went to.

    I'll take it for a drive tomorrow to see how it feels, but I'm not hopeful. Any other ideas?
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  9. HTC
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    HTC Active Member

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    Yeah take it for a drive to see. As for replacing the parts. Audi will tell you that you have to renew the complete loom!! but you don't have to.
    You can buy the connector end if you need to and wires with the clip in metal parts separately.

    The only thing you would need to do is cut the old wires and solder/heat shrink the new ones on. Or get an auto electrician to perform the task.

    Let us know how you get on.
    #9
  10. amb276s3
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    amb276s3 bird spotter

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    took mine back to audi for repair, pointed out the problem to them, after a day and a half of "checking it" they repaired the loom as it was not covered,(as is any wiring), by the extended warranty for a whole replacement. cost me around £90, good as new now .
    #10
  11. Jodi
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    Jodi Starsky

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    Will take it out for a reasonable run tonight to see how it performs. I must say I can't quite see what problems the bare wires could cause as it didn't look like they could short to anything. If it still isn't good I'm going to check a couple of things again:

    1. Look at the new plug that's in cylinder 4. If it is covered in fuel that will add to the evidence against a problem related to that cylinder.

    2. Check the old coil pack from cylinder 4 in cylinder 1. If that works, then it will point towards loom or something else related to cylinder 4.

    If (and I can barely bring myself to even suggest it) there was a loss of compression in that cylinder would the symptoms be as I am experiencing - slightly rough idle, strange exhaust note, unburnt fuel on plug, but reasonable running once going?
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  12. Jodi
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    Jodi Starsky

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    Really confused guys.

    Car was only slightly odd at startup pulled away all was fine. Noticed that not all power was there, but not far off being right.

    Once the car is above 1500 rpm the car feels smooth as you like. I can't believe that it is only firing on 3 cylinders. 6th gear at 80, just tap the accelerator and it was pulling. It was just too smooth to be anything but normal. After about 15 minutes mixed driving including motorway I pulled into my mates drive, drop into neutral and it was as lumpy as hell!!! Aaarghh.

    Start up 10 mins later still lumpy, pull away (giving it a few more revs than normal) and we're off again. As before, when I get up to speed it's smooth as you like, but as you slow down and the revs drop I can hear the exhaust (sounds like it's blowing a bit).

    Now for the really weird bit....after a further 5 mins the air con stopped working. Every time I tried to put the "fan" sign on it would immediately switch off!?!?!

    We reached our next destination, stopped for 10 mins or so and off we went again. Same story, lumpy idle, smooth at speed , exhaust sounds like its blowing at lower speeds and now the air con was working again!!! The damn thing was running smooth as you like at 70+, pulling with good force well into 3 digits. Surely a car running on 3 cylinders couldn't perform so well up in 3 figs even one with 275 bhp, could it?

    What's going on? Could it be:

    1. Intermittent ignition lead failure (that doesn't ever occur at high speeds only at low revs and idle and even then not all the time)?

    2. Dodgy battery?

    3. Dodgy alternator?

    4. Exhaust problem?

    5. Something else?

    Under what conditions can the air con pack in and then come alive again? This is driving me nuts guys please help me stay sane and financially sound.....

    Yours very perplexed,

    Jodi
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  13. jojo
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    jojo S3 Drift King! Staff Member Moderator

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    The ClimateControl will deactivate the compressor( ice symbol ) if the outside temps are below 5*C, to prevent it from freezing up, so it's working perfectly.
    As for the idle, could be a sensor problem?, what revs is your car holding during idle?
    #13
  14. HTC
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    HTC Active Member

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    Check injectors as well. Duty cycle and wiring.

    Agreed, Air con switching off at low temps is normal.
    #14
  15. starski4578
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    starski4578 Member

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    Nice one jojo, thats cleared that one up for me about the symbol not staying on(air con) /ubbthreads/images/graemlins/beerchug.gif. I too thought i had a problem. Cheers
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  16. AL_B
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    AL_B Active Member

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    Have you tried changing the coolant temp sensor? Worth a go for about £35.

    Have you tried running with the MAF disconnected? Is it smoother then? If so, your MAF could be on the way out.

    Apologies if you have already tried these.

    AL
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  17. Jodi
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    Jodi Starsky

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    Guys,

    Thanks for the input.

    JOJO - The car idles at just over 800 which is normal I believe? You can just feel that it's lumpy/missing. Today on initial start up I had to give it revs to get away without stalling. Thanks for the info on the A/C. It's probably done that loads recently, it's surprising what you notice when things start to go wrong that you didn't see before.

    HTC - What should I check for on the incectors and how? Duty cycle?

    AL - I had a new coolant temp sensor fitted a couple of weeks ago as it did show as an error code on VAGCOM. It's made no difference, however auto choke works much better and idles settles much better.

    I will do some more playing tonight. Sorry about all the questions, but I hate to be beaten or give in.

    As an aside if the MAF is on the way out (and a new one was supposedly fitted at last service approx 10k ago) would this cause the car to miss on one cylinder only?

    Cheers guys,

    Jodi
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  18. HTC
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    HTC Active Member

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    I'll look up the proceedure for checking injectors a bit later for you. It's likely to involve VAGCOM as I know you can fire them with the engine off via laptop.

    The pikey way would be to remove them one by one, place them in a jam jar and run the engine for a few seconds whilst watching the spray pattern.

    Like I say I'll check the proceedure when I get home.

    Have you checked the compression on that cylinder yet? Might be worth a trip to halfords to buy a compression tester as they are cheap and at least you'll know then if you've got something major out or not.
    #18
  19. Jodi
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    Jodi Starsky

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    Further update.

    Last night took car for a short run around the block. Nothing too untoward. If you didn't drive the car everyday like I do then you wouldn't notice anything. Car was boosting in 1st and 2nd gear fine.

    This morning I checked the battery for the hell of it. All was as I'd expect 12 and a bit volts and 14 and a bit volts with the engine running. Went back to the seat to turn the engine off and the RED temp light was displayed on the DIS?!

    I had the coolant temp sensor and seal replaced a few days before christmas. A few seconds after switching the engine on it displays every time. I did the self check with the engine off (press the switch by the clock twice) and everything was ok. I'm guessing that if the temp warning comes on just after you switch the engone on then the sensor would be faulty or is it trying to tell me something else?

    I also put the old coil pack from cylinder 4 into cylinder 1 and didn't notice any extra lumpiness so looks like the misfire isn't down to coils.

    Anyone have any other ideas. AL you asked if the temp sens was ok. If it's not what effects would you expect to see?

    Thanks in advance.

    Jodi
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  20. craggy_t
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    craggy_t New Member

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    Hey Starski,
    I had this exact same problem on my 1.8T. Same symptoms.
    After extensive playing around it became apparent that the IGNITION MODULE was faulty and failing to forward the instruction from the ECU to put a spark on my No.2 plug.
    A quick 2 minute job and the car is running perfect again!
    A quick way to check this is get a light circuit tester and apply the positive terminal to each of the four contacts on the smaller plug. Watch for a strobe light effect on each one.
    One of mine was missing!
    Audi want around £400 to fix this but I know of a couple of places that'll do you one for around £80 - £90 with 3 years warranty.
    I've got the e-mail for a guy on ebay who'll do it for £30, but no warranty
    Hope this helps, Craig
    #20
  21. Jodi
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    Jodi Starsky

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    This sounds promising. Did you get the temp sensor on the DIS too?

    When you talk about the 4 contacts in the small plug I'm guessing that you mean the plug that connects to the coli pack?

    Do you know where the ignition module is? Will the fix affect my re-map?

    Jodi
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  22. craggy_t
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    craggy_t New Member

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    [ QUOTE ]
    This sounds promising. Did you get the temp sensor on the DIS too?

    When you talk about the 4 contacts in the small plug I'm guessing that you mean the plug that connects to the coli pack?

    Do you know where the ignition module is? Will the fix affect my re-map?

    Jodi

    [/ QUOTE ]

    No need to get the temp sensor done on mine.

    Can't see the direct wiring coz it disappears into the loom. There are only two plugs on the module. A 5 pin and a 4 pin. Mine is under the cover for the air filter housing and it sits nicely on top making it really easy access. (My part number is 4D0 905 351)

    It shouldn't affect your remap because the unit is basically an amplifier.

    Best of luck
    #22
  23. Jodi
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    Jodi Starsky

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    [ QUOTE ]

    A quick way to check this is get a light circuit tester and apply the positive terminal to each of the four contacts on the smaller plug. Watch for a strobe light effect on each one.
    One of mine was missing!


    [/ QUOTE ]

    Can you do this with the engine running. I'm just wondering how you get the ignition module to fire if it's disconnected as the engine won't turn over. Sorry for being a little dense I had a late night last night.

    Jodi
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  24. craggy_t
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    craggy_t New Member

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    Can you do this with the engine running. I'm just wondering how you get the ignition module to fire if it's disconnected as the engine won't turn over. Sorry for being a little dense I had a late night last night.

    Jodi

    [/ QUOTE ]

    You have to have everything connected and the engine running to check for the spark plug signal. You can pull the rubber gromit from the back of the plug and put the tester probe in there.
    #24
  25. Jodi
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    Jodi Starsky

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    I thought I was losing it for a mo. That makes sense. Thanks for the info. I'm not going to get a chance to check for over a week as I'm off to St Anton tomorrow for my annual boarding trip. Can't wait.

    I may get back in touch if I need a new unit so that you can tell me who your contacts are. My parents live in Peterborough which isn't a million miles from Lincoln.

    I hope this is the answer.........
    #25
  26. craggy_t
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    craggy_t New Member

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    Okey Dokey, Have a good trip. I was boarding in Tignes just after Xmas and it was awesome!
    #26
  27. AL_B
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    AL_B Active Member

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    [ QUOTE ]
    . AL you asked if the temp sens was ok. If it's not what effects would you expect to see?


    [/ QUOTE ]

    Most people arribute lumpy running to temp sensor and/or MAF, so just wanted to know if you'd changed them, in order to rule them out. Which you have.

    I'm stumped mate. You've tried a lot now.

    Like you say, I guess next is testing the injectors, like HTC says.

    AL
    #27

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