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misfire on boost help please

Discussion in 'A4/S4 forum(B5 Chassis)' started by rob_1986, Jul 4, 2013.

  1. rob_1986
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    rob_1986 New Member

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    hey all am new to the forum ar rob i have a 1996 audi a4 1.8 turbo
    i bought the car and had a misfire when boost tried to come in so i bought new spark plugs and it seems to run alot smoother n better but again when boost comes in it will misfire and u dont get the boost :( any ideas ? also the n75 valve has been taken out and running a manual boost controller also new diverter vavle fitted cheers
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  2. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    I had the same problem changed to later coil packs and icm delete, no more missfires under boost !!
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  3. rob_1986
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    rob_1986 New Member

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    did the car idle fine and run fine if u didnt boost it ? and are the late coil packs bolt down or just push down ? and what is the icm delete ? sorry new to audis cheers
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  4. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    Basically you can use the bolt down hitachi coils or 2.0TFSI coils and adapters.

    you need the repair harness for the mk4 platform 1.8T's with 4 pin coils and you pull the wires out the loom from the icm and the original wires and wire it to the repair harness.

    some pics

    [​IMG]
    [​IMG]

    I used a 16 pin male and female connector from a citroen (as i work there and was easily obtained) and allows quick release, or you can just solder them,
    [​IMG]

    finished product :)
    [​IMG]
    #4
  5. rob_1986
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    rob_1986 New Member

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    ok cheers mate ill give it ago see what happens
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  6. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Check for boost leaks.

    I wasted days chasing missfires on my mums replacing all sorts of ignition components, and it turned out one of the small hoses off the inlet manifold was split. Fixed the hose and no more problems.
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  7. rob_1986
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    rob_1986 New Member

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    cheers well i just bough some coils today part number 0 040 100 013 will see if they make a difference if not i have a roll of vac pipe so will replace them too
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  8. rob_1986
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    rob_1986 New Member

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    right 1 thing sorted no misfire at all now after changing vac pipes but now am not getting any boost at all u can hear the turbo whistle but no boost at all feels gutless any ideas ? also how do you have your turbo set up as i am running actuator pressure to inlet manifold cheers
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  9. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Why do you have the actuator connected to the inlet manifold? Whats the N75 doing?

    Post some pics of the pipework.
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  10. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    But your missfire is under boost so hows that sorted when you have no boost ????

    Pics of pipe work as above !!
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  11. rob_1986
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    rob_1986 New Member

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    i have no n75 valve installed this is how i got it and misfire is sorted as its no longer there but still does not boost just runs like a normal engine with no turbo :( how would the pipe work be set up with no n75 valve ?
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  12. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    With no n75 it should just be off the port of the turbo to the wastegate, are you sure theres no n75 on the TIP and your not talking about the n249 under the manifold ???

    even with the pipe from turbo to wastegate you should see actuator pressure of 4 psi iirc
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  13. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    Post some pics up as they will explain alot about your current setup !!
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  14. rob_1986
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    rob_1986 New Member

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    hi mate i tried ro run A pioe from actuator to turbo housing and made no difference and yes defo n75 vavle near air intake pipe had a mate come up today with a scanner and it come up with temp coolant sensor fault and n75 error but obvious there is no n75 lol cheers for getting back to me struggling to get pics at moment as phone broke
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  15. rob_1986
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    rob_1986 New Member

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    i will put the n75 valve on tomoz along with new coils and new diverter valve and see wat happens and also brake bulb icon come up on dash but doubt that will effect the boost at all
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  16. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    Just few things to ask

    Is there a single vac pipe from the front of the manifold to the diverter valve ??

    have you replaced the fuel rail pressure pipe at the back of the manifold ??

    if you have put a pipe on the actuator and turbo comp housing you should see actuator pressure have you got a boost gauge plumbed in ??

    also if theres no boost it could be the wastegate penny valve in the turbine housing thats gone have you had any abnormal noises on overrun ??

    what diverter are you running ??

    Have you tried unplugging the maf to see if its any different ??
    #16
  17. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Just noticed the MBC thing.

    Its probably not a missfire, its probably fuel cut from trying to run too much boost?
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  18. rob_1986
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    rob_1986 New Member

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    hi mate thanks for getting back to me

    yes 1 single pipe from standard recirc valve to inlet manifold
    not replaced the fuel pressure rail pipe as yet
    and not got no boost gauge in at the min
    and ill check the wastegate this weekend
    and unplugged the maf and the car turned off

    cheers
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  19. rob_1986
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    rob_1986 New Member

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    right put the new parts on and the 1st time i started it and give it a test run it boosted once then would not boost again any ideas ? everything back to normal all vac pipes and n75 valve back in place
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  20. rob_1986
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    rob_1986 New Member

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    misfire back again when try to boost so far have replaced new spark plugs,new pipe from standard dv to inlet and had new diverter valve on too and replaced 2 coils too checked on another code reader and not bringing any codes up after a 5 min run could the standard dump valve be a issue ?
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  21. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    Have you replaced the FPR pipe at the back of the manifold, have you tried an icm ??

    swap all four coils for some good ones ??

    try spraying some brake cleaner round your pipe work at idle if you have an air leak the revs will rise but dont spray loads at a time do it in short bursts.

    when you unplug the maf and then start and drive it is it still the same ??
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  22. Oranoco
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    Oranoco Active Member

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    iirc even when throwing an MBC on these if the N75 valve isn't left plugged in the system throws a strop.

    I would look at getting the N75 back in place with it's associated pipework and see hwat happens then. Pics of your current setup would be helpful but, to me at least, it sounds like a cretins been at work before you got it trying to eek more out of it the wrong way.
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  23. rob_1986
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    rob_1986 New Member

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    well i have put all the pipes back to normal how they should be replaced a few pipes with silicone ones but thats about it and the n75 valve is plumbed back in now and connected :) once its running if i discconect the maf the car stalls and wont start till its plugged back in i can hear a slight whistle from the turbo but nothing out of the normal still confused
    #23
  24. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator

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    How do you know it's not boosting if you have no gauge?

    Have you logged stuff on vagcom?
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  25. rob_1986
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    rob_1986 New Member

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    there is no boost i can defo tell had turbo cars before and this is gutless feels like am driving a normal 1.8 20v non turbo and no not had it on vagcom as yet i will try it after fitted new dumpvalve then atleast its had a few new parts which i can rule out
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  26. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    Where you based rob ??
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  27. rob_1986
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    rob_1986 New Member

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    batley near wakefield mate and which is the fpr pipe ? i have checked most of the pipes n stuff and all seem ok am thinking either faulty dump valve or faulty n75 valve its strange caus if i take the n75 valve off i dont got a misfire but i dont get boost either but if i put the valve back on thats when i get the misfire
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  28. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    take photographs of your boost control pipework.
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  29. rob_1986
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    rob_1986 New Member

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    right took the new spark plugs out today and they are black defo carbon build up so wat u guys think ? vac leak ? and sorry carnt get any pics at min as phone broke cheers
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  30. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Well find another one then.

    It could be anything, but without seeing the car, or some photos of the car showing the potentially dodgy pipework, or a fault code scan, or some diagnostic logs, we wont have a clue.
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  31. rob_1986
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    rob_1986 New Member

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    well the pipe work is all clean u can not see any cracks/splits at all thought i would try a few things today so started with the maf sensor i unplugged it and the car did not stall at all it was the exact same but when i plugged it back in the revs went up and down for a few seconds then back to normal ( i did say in other post the car did stall when unplugged the maf that was my mistake it was the ignition amplifier) am new to these cars so learning slowly
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  32. rob_1986
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    rob_1986 New Member

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    and i have scanned the car with a normal scanner and did bring up faulty temp sensor but thats all sorted now and re scanned and nothing else came up
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  33. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    The pipework might not be split, but it might not be going to the correct place...

    How have you plumbed the three legs of the N75?
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  34. rob_1986
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    rob_1986 New Member

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    Right plug facing up as normal then right part going into air intake pipe then middle part going to turbo housing and left part going to actuator this is how it was before so I have put it on the same way
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  35. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    is the long nipple going into the intake pipe, or towards the actuator?
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  36. rob_1986
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    rob_1986 New Member

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    into the intake pipe mate its strange as took the n75 off and capped the pipes and kept the n75 valve electronically plugged in and it wont misfire but still wont boost :( thinking possible faulty airflow maf sensor now as if i start the car and un-plug the maf it dont make any difference to the revs but then throws a code up for the maf sensor on the scanner
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  37. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    worth a try if you've done the coils.
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  38. rob_1986
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    rob_1986 New Member

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    will let you know the out come :) hopefully it will be cured with that then its time to tweak it a little once i know its running right
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  39. rob_1986
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    rob_1986 New Member

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    right back again lol put new maf on and seems alot better getting a bit of boost now but still not like it should be so as everything else done am probs thinking sticky turbo vanes ? got some cleaner so will try it tomoz and see what comes from it :)
    #39
  40. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    1.8T's dont have turbo vanes im affraid only diesels, id be checking the wastegate penny valve as they are also a known problem with our 1.8T's do you have a rattle on overrun ??

    try getting a camera and get some pics up, as saying what youve got to showing what youve got are two totally different views of things !!

    if a friend has a iphone or android take some pics download the photobucket app and upload them and get some thrown on here off hid phone its easy im always on my iphone on here very rarely use the laptop only for vagcom purposes and downloading films (and not those dirty filth ones either before anyone says out lol) !!!
    #40

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