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misfiring in 3rd cylinder, help please

Discussion in 'A3/S3 Forum (8L Chassis)' started by xCoupexAshx, Mar 29, 2012.

  1. xCoupexAshx
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    xCoupexAshx All Torque

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    ive had a problem of not firing up in 3rd cylinder on and off for ages now, joys of intermittent problems.
    latest problem has thrown up this fault

    04EE boost valve output open
    414C knock sensor 2
    023F Intake manifold pressure below control limit

    ive tried new sparks, new coils new injectors,, new maf and new ignition amplifier. still wont wont. any one had a similar problem or shed any light? this car is nothing but a nuscience. German reliability blows lol >.<

    thanks, ash
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  2. jay1601
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    jay1601 Well-Known Member

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    have you done a compression test ?
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  3. murran
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    murran Active Member

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    04EE boost valve output open
    boost valve open circuit. this will leave you with .3 bar max boost. you need this sorting out. the boost solenoid valve controls the wastegate, its on the inlet pipe from the airbox to the turbo, near the recirc valve. theres a two pin plug to it, check for broken wires.
    023F Intake manifold pressure below control limit
    this is to do with the pressure sensor picking up on the fact the boost pressure is too low due to the boost solenoid fault above.
    414C knock sensor 2
    you need to check the wiring to this sensor. there are two knock sensors bolted to the block under the inlet manifold. sensor 1 is inbetween cyl 1+2, sensor 2 is inbetween cyl 3+4.
    did the fault code say what was wrong? low resistance? high resistance? short to ground?

    non are directly related to a specific cyl misfire. how do you know its no.3 thats misfiring?
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  4. xCoupexAshx
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    xCoupexAshx All Torque

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    thank you very much =] ive tried unplugging the leads to the coils while running and on the 3rd cylinder from the left (ie. 1 2 3 4) that doesnt affect the car, yet if you pull out 1,2 or 4 you hear the car drop down in rev's/power. tried swapping coils round, new sparks. and swapping injectors round and its always 3rd cylinder where if wont fire up it seems.

    ill check the top solution one monday. but as you said i dont think it will solve the misfire issue =/ speaking to someone today and said could be a wiring fault from the ecu to the coil. would i have to continuity test the whole length to check this?

    on the knock sensor, says signal too low. sorry forgot to include that.

    and yeh compression test came up fine
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  5. murran
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    murran Active Member

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    ah signal too low. if you undo the 13mm bolt holding the sensor to the block, corrosion might have got in between the mating surfaces. if it has, sandpaper them up and refit. the sensor should be correctly torqued up. 25nm i think... (but check up on this).
    if the mating surfaces look clean if might need a new sensor.
    or to be sure, swap it with the "sensor 1" as they are interchangable. see what happens.........

    reguarding the misfire.... have you not got a fault code for it "misfire detected cyl. 3" stored in the ecu?
    if its not lack of compression and the coil just isnt firing the spark plug... then yes the wiring needs checking back to the ecu. get a wiring diagram etc continuity checks etc. ecu plug to the coil plug.

    if you can wait while monday i can print the diagram off autodata at work and tell you the pin numbers.
    what engine code and year is it?
    Last edited: Mar 31, 2012
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  6. xCoupexAshx
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    xCoupexAshx All Torque

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    that would be effing fantastic mate, so appreciated =] ill pm you my email address if you could send it over? and sure thats no worrys. na they were the only 3 errors that came up. i shall try these fixes monday tho wen im bk in the garage and hopefully know from there :)

    its a 1998 a3 1.8t agu engine
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  7. murran
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    murran Active Member

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    cant email it mate, i can print it off and bring it home and tell you pin numbers, wire colours etc.

    might be able to scan it in on the printer and email it that way. i'll ask our lass, im not right up on this shizzle.
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  8. xCoupexAshx
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    xCoupexAshx All Torque

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    haha ok mate, thanks all the same =]
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  9. xCoupexAshx
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    xCoupexAshx All Torque

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    just to let you know, its cos where i moved the ignition amplifier cos theres no airbox anymore, it wasnt earthed properly. hopefully that will have fixed it, works so far. im a douche ^_^ lol
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  10. murran
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    murran Active Member

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    but the airbox is plastic. how would it be earthed?
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