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Help, a few faults :(

Discussion in 'A3/S3 Forum (8L Chassis)' started by Ian123, Aug 20, 2009.

  1. Ian123
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    Ian123 New Member

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    [Aug 20, 2009]
    Hi all,

    My name's Ian. Got a 2000 A3 Quattro Turbo. As far as I'm aware it's been remapped and has the obvious addition of an FMIC. It was flying and running great until recently.

    To quote the guy that did the vagcom for me "FMIC install looks a little slap-dash" :laugh:

    Anyway, to diagnose whatever's wrong with it they'd need it in for the day and could end up costing a fortune for the diagnosis alone.

    Basically, it's running fine driving normally, but try and boost it and you'll get that initial kick then it's like it's hit a wall and won't give it anymore power.

    I'm sure I can hear the sound of air escaping which leads me to think it's a leak. Spotting where tho is a bit of a struggle. All pipes/hoses have been tightened, etc.

    The faults were as follows... :(

    16500 - Engine Coolant Temp Sensor
    Signal Intermittent

    16622 - Manifold Pressure / Boost Sensor
    Signal Too High

    16486 - Mass Air Flow Sensor
    Signal Too Low

    16490 - Manifold / Barometric Pressure
    Implausible Signal

    17743 - Engine Torque Monitor 2
    Maximum Limit Exceeded

    17521 - Oxygen Sensor B1 S1
    Internal Pressure Too High


    I already knew about the coolant temp sensor problem and this was about before this recent problem started.

    Am I right in thinking that an air leak could trigger all of the above?

    If anyone could suggest anything then I'd be very very greatful :)
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  3. Ian123
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    Ian123 New Member

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    [Aug 20, 2009]
    Oh, and I've been reading a lot on here and I know the usual answers are N75, 710N, MAF, MAP, Actuator arm, etc.

    I tried unplugging the MAF as recommended and it made no difference. So is it ok to rule that out?

    Is there a way I can test the Recirc, N75, MAP, etc. without buying the new parts?

    Also, coming from the N75, there's a vacuum pipe that just leads to no where and appears to have no where to plug into either :think:
    Last edited: Aug 20, 2009
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  4. ash_pearce
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    ash_pearce Member VCDS Map User

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    [Aug 20, 2009]
    Hi mate, welcome to the forum!

    Firstly where are you based? We are a friendly bunch on here and serveral members will pay you a visit for the price of a beer to vagcom for you. You should really clear all faults and go for a drive to see what faults are re-occuring.

    The coolant temp sensor is vital to the engine running correctly, its a cheap part and should be replaced first.

    As for the map sensor signal too high, as a guess this will be related to the spare vac hose off your n75. It has three conection, 1 into the intake pipe, 2 a boost feed of the top charge pipe, 3 exit down to the wastegate. if this is unolugged basically your waste gate isnt opening, giving you insane boost and the relating fault!

    Let us know where you are based and then ask nicely for help.
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  5. Ian123
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    Ian123 New Member

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    [Aug 20, 2009]
    Hi Ash,

    Thanks for the reply :)

    TBH at this moment in time I'd offer more than a beer to sort it. I don't mind paying my way, it's just the garage was far too vague to keep me feeling comfortable.

    When it is boosting on occassion it is pretty insane :laugh: Not sure what pressure it's at when it is tho.

    I think it's the boost feed from the top of the charge pipe that currently has no where to go. Does this feed what the pressure is to the N75 then? I hope this is the answer to my problems, I really do lol Struggling to think how I'd connect it up tho? Is there another line I could tap into easily or anything like that?

    Really really appreciate the help.

    Oh, almost forgot, I'm based in Manchester, Ashton-U-Lyne way. I wouldn't give it a second thought travelling for the help tho.

    Oh, another edit, I'll be sorting the coolant sensor tomorrow afternoon as I have an early finish. I pass an Audi dealer on the way home too :)

    Thanks again :thumbsup:
    Last edited: Aug 20, 2009
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  6. ash_pearce
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    ash_pearce Member VCDS Map User

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    [Aug 20, 2009]
    That would mean your boost is escaping through that pipe then. It does in a way feed the n75 pressure, have a look at this for more info on n75 operation
    http://s2central.net/images/boost_control.jpg

    There should be a connection on the metal charge pipe at the back of the engine that comes off the turbo and heads towards the i/c. There are two side by side one for the recirc valve about 20mm diameter and the other for the n75 bout 8-9 mm diam'.

    see here http://i29.photobucket.com/albums/c259/jjhsoccerodp/n249/CIMG2613.jpg

    edit ignore the red circled bit on the photo, its not mine(google images)
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  7. Ian123
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    Ian123 New Member

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    [Aug 20, 2009]
    Would it mean it was escaping tho? As the hose is literally coming from the N75 and leading to no where, not the other way round. It should fit fit onto the dark blue pipe in the first diagram, which is the pipe shown in the second picture if I'm right?

    The thing is, that pipe in the second picture has been totally replaced with another one. From that pipe there is only one connection on the top and that's the one to the recirc valve, hence why this other hose leads from the N75 to no where.
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  8. markyR
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    markyR Member

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    [Aug 20, 2009]
    sounds like the intercooler fitted by the previous owner doesn't have a n75 feed on the charge pipe persuming the charge pipe is new i.e fitted with the fmic kit. You may have to use a quick tap or drill a hole with an adapter and seal appropiately then put the n75 boost hose on that.

    i'm looking at getting an intercooler my self and this is what i will need to do as the pipe doesn't come with it.
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  9. Ian123
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    Ian123 New Member

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    [Aug 20, 2009]
    So you guys reckon this would be the answer to all my problems?

    In theory, I could tap into the line that goes to the DV right as it's coming from exactly the same place? Think it'd be easier doing it that way than drilling into the pipe and trying to seal it. Not that it's ideal, but it'd be easier for me to fabricate a t-piece with 2 x 20mm ends and 1 x 8mm end coming off it using plumbing gear.

    Cheers fellas.
    Last edited: Aug 20, 2009
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  10. ash_pearce
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    ash_pearce Member VCDS Map User

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    [Aug 20, 2009]
    well lets not jump to far in front but i would say that it should cure alot of your problems. with out an n75 feed the ecu has no idea of what boost is being created and so thats why your getting alot of boost and then nothing. what you said about tapping into the dv pipe will work fine as long as its sealed 100%.

    Get that done and the coolant sensor and you should be fixed (hopefully)
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  11. Ian123
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    Ian123 New Member

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    [Aug 20, 2009]
    Fingers crossed :)

    Will sort those out this weekend and report back. You've been a big help, Ash, cheers :icon_thumright:
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  12. ash_pearce
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    ash_pearce Member VCDS Map User

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    [Aug 20, 2009]
    no worries mate, hope you get sorted!:salute:
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  13. ash_pearce
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    ash_pearce Member VCDS Map User

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    [Aug 25, 2009]
    How did you get on bud?
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  14. Ian123
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    Ian123 New Member

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    [Sep 1, 2009]
    Hey Ash,

    Sorry for late response, had a rough week last week.

    Followed through the idea and fabricated my own t-piece with 2x22mm ends and 1x8mm end with plumbing gear and EVERYTHING is sorted! Replaced the coolant sensor too (only £20) and the car is absolutely spot on now :icon_thumright: Not one single fault, as it should be.

    Thanks again
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  15. ash_pearce
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    ash_pearce Member VCDS Map User

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    [Sep 1, 2009]
    Glad your sorted mate!
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