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AAN in T3 Syncro 16 - misfire above 10psi boost

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  • #16
    Hi Michael, check the MAF terminals / connector and injector harness condition
    Panthero Coupé quattro 20vt
    Indigo ABY coupé
    Imola B6 S4 Avant

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    • #17
      Originally posted by RS2 View Post
      Update time. I've been trying out a modern setup of TFSI coil packs and a conversion loom from another S2 member (who knows his stuff, I trust his workmanship) with the following results.

      First fit of the loom and TFSI coils resulted in a permanent misfire on cylinder 4! It would not clear. This was done fairly late in the evening so I couldn't spend time swapping parts over to see what would clear the misfire. I could only put the standard setup back on for driving to work again the next day.

      To me, this proves that it's definitely an ignition fault and that the standard setup is giving the spark plugs a much better spark than the TFSI setup... but I still have no idea why I'm getting the misfire under boost.

      Any ideas? MG
      A TFSI coil conversion with new coilpacks should not have any misfire issues, assuming the plugs are correct. I would have swapped coil NO. 3 with coil NO. 4 and checked whether the mis migrared to cylinder No.3 = bad/weak coils pack.
      RS2'd 93 UrS4 5 spd sedan
      94 UrS4 V8 6 spd manual avant

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      • #18
        The problem I have is that when I had the misfire, I didn't have time to swap the parts over. I would have done but this is my only running vehicle and it was gone 10pm. My neighbours already hate the van!

        I understand checking out sensors that are related to the ignition system but how can the injection loom have an impact on this?

        MG

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        • #19
          As others have said, substitution of a known working coil pack would have given an indication of whether it was just a duff coil or perhaps a wiring issue to that coil. After all you are basically eliminating the troublesome/expensive numerous OE components for a single cheap troublesome component!
          Going back to your original post, you claim to have a 3 bar external map sensor and a chip. What exactly are these and are they compatible. Most chips for std components usually stick to the stock 2.5bar internal map sensor.

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          • #20
            http://www.s2forum.com/forum/showpos...&postcount=103
            Ah! Thought I had contributed before.
            My comments still stand. Unless anything comes up in the ecu field when running VCDS it will be impossible for us mere mortals to tell the origins of these chips. From what little I know they are not the OE ones and the boost chip appears to have a slower access speed then the 200NS that the OE one has. Whether that has a impact on overboosting or not I am unable to answer. From what I was told it was good practice to use an equivelent or faster access speed.
            Then there is the scaling of that map sensor!
            Shame its not on a stock map sensor as it might have been advisable to trouble shoot it on stock chips assuming the rest of the engine is stock.

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            • #21
              Originally posted by twoqu View Post
              Most chips for std components usually stick to the stock 2.5bar internal map sensor.
              Not in my experience.

              Agree Stage 1 = stock 2.5 Bar MAP sensor with stock everything else = 260/270 crank hp

              Agree Stage 1+ =3.0 Bar MAP sensor with stock everything else = 270/280 crank hp
              RS2'd 93 UrS4 5 spd sedan
              94 UrS4 V8 6 spd manual avant

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              • #22
                When you had the plugs out to gap them, what colour were they? I would agree that by the sound of things you've got an ignition issue but I wouldn't rule out fuelling either. My last car had symptoms exactly like you're describing and it turned out to be under fuelling that was the issue.
                You've not disturbed anything fuel related recently have you?

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                • #23
                  Thanks for the replies.

                  I have a stock ECU which I will fit and try to see if that improves things.

                  I have no idea what chips the modified ECU is running or which MAP sensor it is, but it's external and not very pretty!

                  Before doing that, I will probably try to replicate the misfire with the new setup so that I can swap things over to see what might clear the misfire. Something tells me that nothing will get rid of it out of the new kit. I'm very disapointed that the new setup seems to have less power going to the plugs than the standard setup. It did occur to me however that I'm not running as much bhp/torque as an RS2 and they use the same setup.

                  Stage 1+ is what I expect the engine to be running.

                  I plugged in this morning on the way to work and checked for faults and to read the measuring blocks on the drive.

                  No faults, nothing at all.

                  A couple of interesting points from reading the measuring blocks though.

                  Intake temp started off around 7-8oC which makes sense. But, once driving along (even at speed) this was reaching 28-30 oC. My drive is only 25 minutes so it was still 7-9 oC outside. In traffic (stationary) it reached 36 oC!

                  The misfire doesn't occur when the engine is colder but then, it also doesn't reach full boost until it's warmed up either.

                  There is also a measuring block that mentions the ABY engine code. I'm not sure why and what this has to do with things...

                  MG

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                  • #24
                    Oh, no I haven't changed anything re fuel system. I did check that it was running at the correct pressure and holding that pressure.

                    The misfire fault occured after I had the van running properly (getting 22-23psi boost) for only 5 days.

                    Previous to that, the engine never boosted over around 10-12psi because of a faulty MFTS.

                    The plugs all looked clean, I have a photo somewhere...

                    MG

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                    • #25
                      what I think is more important here is "AAN in T3 Syncro 16"

                      SHOW ME
                      sigpic
                      "For what you spent on that you could have brought a new car"
                      BUT I DON'T WANT A NEW CAR!

                      1995 S2 Avant, Volcano Black
                      1982 VW Golf Mk1, primer yellow, will be finished one day, maybe.
                      2003 VW T4 long nose X pack, (has become project)

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                      • #26
                        With the conversion setup on.



                        The plugs that I was running previously...



                        The fuel pressure after an hour...



                        MG

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                        • #27
                          Obviously the COP should improve things over the tired OE stuff. If not then its either the loom or a faulty coil pack.
                          The loom should be easy to check for continuity particularly if you suspect a particular cylinder. It may well be that a pin is not seated correctly or worst case not in its correct position which can be checked against a schematic. Basically its power, earth and the signal. You could check for at least two of those when installed.
                          Other than that I would buy one new coil to trouble shoot, its always handy to have a spare on board anyway.
                          The ecu issue can wait. But it sounds like you must have ABY SW as the AAN didn't have use the MFTS as a safeguard. This might be important as USUALLY (for Dave's benefit) it was only the AAN conversions that used a 3 bar map sensor to allow more mid range boost to move the bulk and lardy NA backsides at the same pace as us less obese S2 owners in Europe which had to make do with 2.5 bar map sensor conversions.
                          Post up what VCDS says the ecu is. I still fear that there might be a issue here but I don't think it has anything to do with the ignition. VCDS will ID the ecu by the chips I believe. Of course any reputable vendor would have put ID labels on the chips. Certaintly MTM did a 3 bar AAN version.
                          Its probably a simple fix, at least for the ignition.

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                          • #28
                            Err aren't those the wrong type of plugs anyway. Should be single prong not triple.

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                            • #29
                              Not sure I am thinking straight at this time of night but I wonder if someone before has changed the POS on NO4 cylinder so that the new loom is actually not connected to the signal from the ecu. Here is Dave's explaination:
                              http://forums.quattroworld.com/s4s6/msgs/15284.phtml
                              It would explain why it works with the stock loom/components and not with the new.

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                              • #30
                                Less obese 2 owners
                                The COP harness is one of mine. I have provided Michael with a pin-out so that he can double check it.
                                It could be that the POS plug pin has been moved; it should be obvious as it won't mate with the pins in the COP harness.
                                Panthero Coupé quattro 20vt
                                Indigo ABY coupé
                                Imola B6 S4 Avant

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