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Thread: 2.7t misfire

  1. #1
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    2.7t misfire

    PLEASE CAN SOMEONE GIVE ME SOME ADVICE,I HAVE A 2000 A6 2.7T THAT IS RUNNING VERY POORLY SHE WILL ONLY REV TO ABOUT 3000 AND THATS IT.TOOK IT INTO THE GARAGE AND HOOKED IT UP TO THE COMPUTER IT SAID FAULT ON PLUG 4 SO CHANGED ALL PLUGS AND STILL THE SAME SO SWAPPED COIL PACK OFF NO3 AND FAULT CAME UP ON NUMBERS 3 AND 4 SO PUT NEW COIL PACK ON AND STILL THE SAME PROBLEM ON NUMBER 4 BUT RUNNING EVER SO SLIGHTLY BETTER IF ANYONE HAS ANY IDEAS THEY WOULD BE MUCH APPRECIATED.

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  3. #2
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    Have I read this correctly?

    If you swapped nos. 3 & 4 coil packs over and the scanner then said fault on 3 and 4, is this because you have put a faulty coil onto No. 3 and the scanner has read the earlier fault AND the new fault on No. 3? You then put a new coil on No. 4 when in fact the suspect pack is now on No. 3, not on No 4. If this is the case, the car would STILL be running on 5 cylinders and a perfectly good coil pack, originally from No. 3, is now in the bin?

    Just a thought . . . . .

  4. #3
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    no swapped 3 back onto 4 so only fault was coming back on no4 no problems on no3 just on 4?

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    Sorry, misunderstood.

    I take it you have changed HT leads too. Very often a fault code will be registered for a particular cylinder "misfire" due to a high or infinite resistance HT lead. This is due to the voltage output of the coil pack going very high and the current going very low. This will reflect back from the coil secondary into the coil primary winding thereby altering the parameters that the ECU is expecting to a position outside of its "software window".

    Worth a try?

    Any other symptoms?

  6. #5
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    Is she rattling on startup at all?

    I ask this as some of the 2.7T engines are known for having chocolate camshafts and as a consequence of this they self destruct.

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    no other symptoms been back into the garage and now the computer is saying that somewhere coming of number 4 plug and going to the ecu there is a wire going to earth or a bad earth?

  8. #7
    Liskeard Classic Cars

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    Andy...Not sure what engine you have (2.6 or 2.8 - not sure about a 2.7!) but we had one in about a year ago that kept showing 4413 and 4414 codes as if it was the injectors. We traced the low tension wiring back (From the injectors to the ECU) and found breaks in the wires that showed on the meter but were invisible to the naked eye but only where they ran accross the top of the engine - the rest of the wiring was ok.
    Once replaced the misfire was annoyingly still there but was a lot better. Further investigation showed ver high resistance in all of the HT leads which were replaced - Problem cured.hth
    Al

 

 

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