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    1. 04-01-2002 08:02 PM #1
      Alright.... don't have a book for this car. Bentley recently released the CD-ROM edition, but I'm holding out for the actual book format. Anybody have the CD?

      The 1551 reports that cylinder #1 is misfiring quite frequently; car runs like crap; exhaust smells of raw gas.
      1551 does NOT report any error codes.
      Check engine light is blinking.

      Remove the harness connector going to the cylinder 1 coil pack and there is no noticeable change in engine speed/sound/etc.

      Test for spark on coil pack #1, no spark. Use same test on pack #2 -- Spark. So my test is ok, and I don't have spark on pack #1.

      Swap pack #1 and #2. 1551 reports that cylinder #1 is misfiring... remove connector from cylinder 1 and get the same results as before. Just for ****s and giggles, remove connector at coil pack #2 (which was just swapped --- was installed in cylinder #1 position), car runs much rougher and idles much lower... then died)

      So... at this point I know for a fact that the problem is lack of spark on cylinder #1, and I know for a fact that the coil packs are in proper working order.

      Test on the coil pack harness connectors:
      pin #1 on numbers 2, 3, 4 pack conncetors measure about 130k to ground. On pin #1 of pack #1 harness, I get about 9 megs or so (can't remember for sure now... damn! It was something rediculously high as compared to the others)

      pin #2 on all of the connectors measure 0 ohms to ground... so they're all tied to ground

      pin #3 on all of the connectors measures +12v (+14 of course when the car is running)

      Having some trouble (again, the manual isn't available yet) tracing the wiring from the coil packs (pin 1/control leads) back... I figured they would lead to the computer, but they don't seem to (which I still don't believe)
      Definitely can't find the same color coded wires at the computers harness (very few of the wires are even the same gauge)... but another problem --- the colors on the wires at the coil packs seem to have faded from being exposed to heat at the cylinder head.


      Anybody out there that has a copy of the schematics?

      It's a '99...

      Dark now, and I don't have tools over here (it's my mom's car)... hate to see her spend money on repairing it ---- looking forward to your replies.

      Thanks,
      Matt MattWebb502@yahoo.com


    2. 04-01-2002 08:44 PM #2
      nah, that's not it... thanks for the input though!

      I just went and checked for spark again on cylinder 1... no visual evidence of arcing.

      So then I moved to the nervous system test... couldn't feel the slightest bit of anything from coil pack #1's HT out...

      tempted to put this POS meter on it for kicks, but I hate to risk damaging working test equipment.

      ...so... once again.
      coil packs are in perfect working order, I have no sparkat coil pack #1. I have +12v and ground at pack #1, apparantly no control from the signal lead at pack #1.
      One more little detail... the crimp on the signal lead at the harness connector checks out to be good.

      thanks again,
      Matt


    3. 04-01-2002 09:57 PM #3
      My Audi had the same problem, although I'm not sure it was cylinder 1. New plug, new wires, new coilpack.....ended up being the computer....dead output to the coilpack. I was about to chip it too. it was covered under warranty. Good luck with your problem.
      14 VW Touareg TDI
      08 Audi Q7 S-Line

    4. 04-02-2002 07:57 AM #4
      Matt:

      So you swapped coilpacks and they worked on a different cylinder, correct? And, you also verified that plug #1 will fire if hooked to a different cylinder than #1?

      I have the CD and can look up the wiring info you need, should be able to trace from coilpack to the pin of the ECU and make sure its not a dead wire or bad connector.

      If the wire checks out then you will probably need a new ecu as bubbleboy said.

      Not sure what the impedance is supposed to be on the control signal, but 9Mohm sounds like an open circuit for sure. Assume there is some kind of FET or transistor output/gate that you are measuring across, probably pulls down to ground to activate the coil but I'm not sure. Bentley might say what it is supposed to ohm out to.

      Probably don't want to drive the car as the raw gas will damage the cat and corrupt/dilute the oil.

      Will try to post the info for you tonight.

      -Scott


    5. 04-02-2002 08:16 AM #5
      yeah... I've prepped her to shell out the cash for a new computer. ******** that these things fail.... this is the second computer in two weeks that I've seen fail.

      - Matt


    6. 04-02-2002 08:35 AM #6
      Problem is definitely wiring related... no question about that.

      > from coilpack to the pin of the ECU and make sure its not a dead wire or bad

      yep yep... that's what I need... would really like to have for four packs.

      > Not sure what the impedance is supposed to be on the control signal, but 9Mohm sounds like an open circuit for sure. Assume there is some kind of FET or transistor output/gate that you are measuring across,

      ahh... but this is even with the computer disconnected. This is a point of confusion.

      > probably pulls down to ground to activate the coil but I'm not sure.

      yeah, but not so simple... usually the drivers are found in the form of proprietary Bosch/Hella control packs. I'll pull it apart tonight and double check on this particular computer, but chances are I'll find the same old proprietary ********... so not much chance of being able to repair the computer without hook-ups at Bosch.

      > Probably don't want to drive the car as the raw gas will damage the cat and

      don't need to worry about that!

      > Will try to post the info for you tonight.

      yeah.... pinout info for the computer harness/coilpacks would be great. Thanks...

      - Matt


    7. Member
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      04-02-2002 08:41 AM #7
      Seems like you did everything except swap out a $2 spark plug. I had a misfire on cylinder #1 first then cylinders #3 and #4 until I went out and bought 4 new Autolite 3923 spark plugs and put them in and BINGO no more problems the car is running strong and not throwing any codes. I would suggest buying 4 new spark plugs and swapping them in, BTW my stock plugs didn't look like they were in bad shape either but replacing all 4 of them solved my problems. At least give it a shot before dismissing it.
      ______________________________
      09 CC
      98 GTI VR6 MKIII.V
      01 Jetta PVW Featured
      00 GTI (RIP 4/01)

    8. Member
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      04-02-2002 09:04 AM #8
      quote:
      Problem is definitely wiring related...

      Wiring terminates at connectors, so after removing the ECU take a close look at the ECU connection plug. Most of the time simply disconnecting/reconnecting a wiring harness plug is enough to wipe the connector clean and make the problem go away (temporarily).


    9. 04-02-2002 09:45 AM #9
      quote:
      yeah... I've prepped her to shell out the cash for a new computer. ******** that these things fail.... this is the second computer in two weeks that I've seen fail.

      She is the original owner, and it has less than 100k. Wouldn't the computer be covered under the 100k powertrain warranty?

      -Steve


    10. 04-02-2002 03:13 PM #10
      quote:

      TOTALLY AGREE!!, hey dude change spark plugs they are cheap and youll have the problem solved.

      I agree that swapping out a $2 spark plug is a good idea in the interest of being thorough, but how is that going to fix an open circuit to the computer? If the wiring harness on one coilpack tests out different than the rest of the harnesses, it sounds like that might be the problem, no?

      -Steve


    11. 04-02-2002 04:26 PM #11
      good point... might be covered under the 100k MI WT.....

      spark plugs aren't going to fix it.

      If you all can tell me that your car produces spark in all four cylinders and you can remove one of the HT leads/packs and expose your hand to cylinder head ground and the HT out and feel nothing at all (hold it there for 30 seconds or more), then I'll buy into it and get some plugs.

      Spark does not exist at pack #1. Pack #1 is in perfect working order when connected to pack #2 harness connector.
      There IS a problem with the pack #1 harness' signal lead... which should lead back to the computer harness.

      As far as the 130k measurements go (remember, with the computer out) --- I figured that was some sort of internal-to-the-harness pull down resistors (weird)...

      measure from pin1 pack 2, to pin 1 pack 3 and you get --- tada.... 260k.

      back to pin 1 pack 1 to ground, 9 mega-ohms or so.....................

      This all leads me to believe that there is a problem with the harness.... I am going to steal a 'scope from work today and throw it on the coil pack pins... see if I'm getting any sort of pulse.

      As far as the connector on-off method goes ("3-on/3-off method" as I know it), has had no effect and visual inspection indicated that the pins were all in good shape. I could take some of my De-oxit Dn5 to it (for those of you who aren't familiar with this stuff... MIRACLE WORKER)


      thanks again for the input everybody... I'll post the results when I find them... which I expect to find tonight.

      thanks,
      - Matt


    12. 04-02-2002 07:14 PM #12
      ended up not getting a 'scope from work... didn't want to mess with the hassle involved.

      Again I tried tracing the wiring back from pin 1 on pack 2 harness connector (known working; known good).... does not lead to (atleast not directly anyways) either of the two ECU connectors or any of the connectors that lead into the car (inside the ecu box)... lowest reading I could get at any of the pins on the computer harness was about 130k .... hmm.

      Traced the main harness as best as I could see and I'm damn near convinced that the coil pack harnesses join with the main fatty harness and enter the ECU box.
      This is bizarre-o, and I'm still in disbelief that they don't lead to any of the pins on the ECU connectors..... but I checked all pins atleast 3 times.

      Also verified that pin 1 on the #'s 2-4 pack harness connectors read 130k or so to ground when the ECU is either connected *OR* disconnected.

      DAMN I wish I had the book for this car.... frustrating pissing in the wind like this.

      Anybody out there that can tell me where these damned coil pack control leads terminate?
      It almost seems that there is a seperate ignition control "computer" somewhere that operates as a dummy slave to the main ECU.


      As far as the 100k MI powertrain WT goes, I looked into it ---
      it seems that it covers all transmission parts (case, internal parts, torque converter, etc), engine and all internal parts (valvetrain, pistons, etc, etc) and really that's about it.......... although the ECU is pretty much life support for the engine, I don't think they're going to cover it. Not from what I read anyways..

      - Matt


    13. 04-02-2002 08:34 PM #13
      presto!

      funny... I started to play with this yesterday, but then stopped fooling with it --- it certainly looked like a driver for something (like a driver for coil packs), but I dismissed that possibility --- didn't even consider it was all the way over on the airbox because it uses it (and the cold air flow) as a heatsink!

      I dismissed the thing as a weird looking new-school VW MAF!
      not the case... this is definitely the driver stage I was looking for.

      The golden rule that was taught to me in my days as an electronic repair technician:

      "The technician is his own worst enemy."

      that rule has, once again, proved itself to be the truth.

      Alright... I'm excited now...
      going back out there and I'm going to figure up pinouts and post them... I hope someone can look this stuff up in their book and give me Bentley test procedures.

      Thanks to Overboost for some solid info.

      - Matt


    14. 04-02-2002 09:16 PM #14
      I planned on setting this thing up on the bench and testing it if it passed the initial tests... looks like that won't be necessary..

      5 pin connector on one side, pin 3 is ground. 1/2/4/5 are control inputs (assuming from the ECU --- they'd better be! )

      4 pin connector on the other side ---

      pin 1 is driver pin for coil pack cylinder #1, pin 1.
      pin 2 is driver pin for coil pack cylinder #2, pin 1.
      pin 3 is driver pin for coil pack cylinder #3, pin 1.
      pin 4 is driver pin for coil pack cylinder #4, pin 1.

      harness for all the packs test out OK, BTW.

      pin 1/4 to pin 3/5 (ground) resistance = 25 megs (did I say 9 before? either way... it's high as sh!t... really no difference to me)
      pin 2/4 to pin 3/5 resistance = a happy 135k (sorry, I said 130k before... whatever)
      same applies for 3/4 and 4/4

      Pretty damned safe to say that this driver pack is very simple and there's nothing weird going on with it--- I'm sure of that.... therefore it's safe to say that these test results are adequate enough to label the component as defective.

      Next step is to determine why it failed.
      I assume it's a heat related failure.... wouldn't surprise me in the least bit. Tomorrow I will perform tests on the driver leads coming from the ECU; I expect to find that there are no problems with the ECU.

      If I don't post any more follow-ups that means that this driver pack was indeed the only problem.... I plan to buy/order one tomorrow.

      if anybody's curious, VW/AUDI PN: 4D0 905 351

      ...I'm curious to see if there's a part number that supercedes it... also curious to hear if it's a common failure. Anybody out there with a newer than '99 1.8T that has a different part number on theirs?

      thanks again EVERYONE for the input.
      - Matt


    15. 04-02-2002 09:31 PM #15
      work at a dealer in your area and it is definetily the ignition module seen it before. about 3-5 times in two years i got a test module in my box. first thing i do when i get a car that has only one or two mis fire codes running rough like that. youll probably have it fixed by the time you read this.

    16. 04-03-2002 12:40 AM #16
      I also have a 99 B5 and I Had the same problem..Cylinder misfire... Changed the plugs and nothing, It wound up being the (ECM) Emissions Control Module.
      Expensive little bugger somewhere around $350.00 HTH

    17. Member
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      04-03-2002 08:37 AM #17
      ECM = Engine Control Module...it controls emissions and gives you a nice red light on the dash when they are too high.

    18. 04-03-2002 11:29 AM #18
      I have the answer....

      Its the lowest sleeve portion of the coil packs is faulty it can be replaced for cheap at the VW parts counter, I have had the exact problem and performed the exact steps of resolution to no avail till my local tech let me in on the secret, not one misfire since...if you need the part numbers and the fix from tech who fixed it call the number at http://www.aprhouston.com and ask for Mike Staley, he will have you fixed quick I promise.....


    19. 04-03-2002 04:33 PM #19
      quote:
      I have the answer....

      Its the lowest sleeve portion of the coil packs is faulty it can be replaced for cheap at the VW parts counter, I have had the exact problem and performed the exact steps of resolution to no avail till my local tech let me in on the secret, not one misfire since...if you need the part numbers and the fix from tech who fixed it call the number at http://www.aprhouston.com and ask for Mike Staley, he will have you fixed quick I promise.....


      no... not the problem. Remember, I swapped coilpacks 1 and 2, problem REMAINED in cylinder #1... the problem is NOT a defective coilpack in ANY WAY.

      The problem, I PROMISE, is not the sleeve of the coil pack, but is the ignition control module...


      now... back to JayBeeSki:
      said ECM ... Emissions Control Module $350.

      Electro Man said
      No..."Engine Control Module".... which controls emissions components and drives the check engine light.

      AFAIK, the MIL is driven by the ECU --- so ECU = ECM.
      I cannot see the ECM/ECU only costing $350.

      my theory on this point of confusion --- JayBeeSki was told "Ignition Control Module" and thought that 'they' had said "Emission Control Module"

      The coil pack driver component, whatever the proper name (Ignition Control Module gets my vote), is going to cost me $250 --- and that's a hook-up price (it's not for me, it's for my parents, so the supplier probabally upped the price a little bit from what he would sell to me for)...
      I could easily see this costing $350 retail.

      Does that clear up any confusion or just add to it?

      - Matt


      [Modified by MattWebb, 1:40 PM 4-3-2002]


    20. 04-04-2002 07:21 PM #20
      finally checked the schematic:

      power output stage traces back to pins 70, 78, 77, and 71 of the 80 pin connector on the ecu.

      coil packs trace back to the ecu at pin 1 of the 80 pin connector.

      coil packs brown/yellow = ground, connects all 4 packs together.

      coil packs black blue = to ecu, connects all 4 packs together.

      coil pack grey/brown = to power output stage.
      coil pack grey/black = to power output stage.
      coil pack grey = to power output stage.
      coil pack brown/black = to power output stage.

      sounds like you have it licked, but thought you migfht want to double check.

      -scott


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