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Boost problems in higher gears

Discussion in 'A3/S3 Forum (8L Chassis)' started by gman_s3, Feb 3, 2010.

  1. gman_s3
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    gman_s3 New Member

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    i had my s3 remapped a few months ago, it runs really well in 1st, 2nd and 3rs gears. When it's in 4th, 5th or 6th gear it doesn't seem to boost properly between 3500 to 5000rpm at which point it boosts ok again.

    the reason i'm finding it hard to know whats wrong is because the problem only persists in the 3 higher gears.

    has anyone suffered from this problem themselves or have any ideas what could be the cause of the problem?
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  2. Welly
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    Welly VX220 SC Driver :)

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    Get VAG COM or find someone with it, run requested vs actual logging (Block 115). At least this way you can see what is going on, and whether the ECU is getting the boost requested. Also, a boost gauge would give you a better idea of what is actually going on....
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  3. badger5
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    badger5 RIP S3dave Site Sponsor

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    does it fluctuate/surge?

    higher loads in the taller gears
    n75 and or plumbing to it could be the culprit
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  4. gman_s3
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    gman_s3 New Member

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    don't have a vagcom unfortunately, but might go to a local diagnostic garage to get it done.

    it doesn't sure, i can the boost building up up to around 3-3500 rpms where i expect it to really pull well but it just doesn't until it hits 5000rpm.

    What do you mean by plumbing to the n75 by the way? i previously had a j-valve but got the standard one back in and didn't notice much difference between them tbh.
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  5. gman_s3
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    gman_s3 New Member

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    i've just taken it for a spin now with the maf disconnected and it was pulling really well through all gears, so it seems as tho the maf is to blame.

    thing is tho i've only just replaced the maf a couple of months ago it was the same story when the maf was brand new. and also why would the maf work alright through the first three gears and not the the other 3 gears.
    could it be the maf itself thats the problem or the way it is being read?
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  6. badger5
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    badger5 RIP S3dave Site Sponsor

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    fueling going to cock when the load is higher probably
    do you run an induction kit? can the maf vibrate at all? is the filter contaminated? was it a cheap maf? do you have bad luck...

    {delete as appropriate - lol}
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  7. gman_s3
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    gman_s3 New Member

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    it's a bosch maf, but i'm just curious as to whether there may be a different maf on the APY engine compared to the BAM or AMK, mine is an APY.

    i've just got the standard airbox also. I think i'm just having bad luck as you say!
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  8. Welly
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    Welly VX220 SC Driver :)

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    You've described me in 5 words!!

    The MAF going scatty in the higher gears is pretty simple, the longer the gear, the more lengthy the reading period will be.

    In 2nd or 3rd for example, it's all over pretty quickly, where as into 4th and 5th the volume of air coming through is higher for longer.
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  9. gman_s3
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    gman_s3 New Member

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    That makes sense. Is the standard maf audi supply the car with a bosch or something else, just so i know before i replace it, again?!
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  10. Welly
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    Welly VX220 SC Driver :)

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    No, the standard MAF is a Bosch I believe. You said you only replaced it 3 months ago? Was that from a main dealer?

    If so, take receipt and give them some stick to see if you can get a replacement for free - or at least discounted.

    3 months worth of use is unacceptable, you expect a MAF to last for longer than that. Even cheap and crappy Ali Benn Singh make ones normally do better than that....
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  11. gman_s3
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    gman_s3 New Member

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    i got it from some local place that stocks bosch parts, this will be my third maf since june now. none of them so far have worked as well as when the maf is disconnected. this place does replace them for free within 6 months tho which is lucky!

    it does make me wander tho that the problem may be due to the socket connecting to the maf or something else maybe. the red bit inside the socket does look a bit worse for wear.
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  12. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    Be aware that if Audi suspect you have an aftermarket filter (green cotton/K&N etc) they will void the parts warranty.. they did that with mine. I had an Audi supplied part that went after 6 months and they blamed the Piper cross panel filter for putting oil on it which was a bit odd as it wasn't oiled... I was running it dry... Just make sure you have a paper filter fitted just in case they ask to see your filter...

    As for the type of MAF, I would personally only ever use an Audi supplied one... I had a Bosch one supplied from GSF but it wouldn't work... they did replace it and even gave me a refund when the Audi one I eventually bought sorted the problem. This is odd seeing as the Audi ones are Bosch supplied but I have never had any initial probs with Audi sourced MAFs...

    Don't even think about using an ebay one either....

    <tuffty/>
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  13. Welly
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    Welly VX220 SC Driver :)

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    I'd second that mate.

    If you've had problems with three MAFs then maybe it's time to swallow the cost and get an OE one. It may just sort your issue forever....
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  14. gman_s3
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    gman_s3 New Member

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    thanks for the advice guys, ill be getting another maf tomorrow from my usual supplier. if that doesn't work ill get one from audi.

    once again, cheers.
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  15. The Stig
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    The Stig Member

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    what about the Pierburg MAF, i seems a better MAF i read....
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