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Another MAF Question (Sorry)

Discussion in 'A3/S3 Forum (8L Chassis)' started by LordNelson, Oct 6, 2009.

  1. LordNelson
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    LordNelson Member

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    [Oct 6, 2009]
    I have finally saved up some pennies to put into getting my S3 running better. I have had it for a number of months now and thought it to be running ok. It felt powerful as my previous car had half the bhp. but now that i am used to it, im feeling that it could be better (as standard) its a 2000 210bhp APY with no mods.

    I vaguely remember reconnecting the MAF wiring harness shortly after i bought it as i had found it to be un-plugged. i thought nothing of it. however, after scouring the forums to educate myself, im wondering that was it un-plugged for a reason.

    Like i said, ive had the car for a cpl of months now and its been running fine. returning 25mpg ave (short journeys). after reading about dodgy MAF sensors and cleaning them etc, i decided to just go out, un-plug it again and go for a blast. Well, i instantly noticed the increase in sharpness and performance.

    so, what i want to know is, what implications does un-plugging the MAF sensor have? do i need a new one or could i just clean it.

    thanks in advance for help :thumbsup:
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  3. Essflee
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    Essflee Well-Known Member

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    [Oct 6, 2009]
    Unplugging the maf will cause the car to run on default setting, if you are noticing the car is quicker/smoother when unplugged then this would suggest you could do with a new maf...
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  4. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Oct 6, 2009]
    Suck it up and buy a new one... they seem to be a fact of life when owning any car that uses one (not just limited to VAG group cars this issue)

    Buy a genuine Audi one from a dealer, ebay one are a lottery and while the likes of GSF will sell you a genuine Bosch, in my experience (and that of a few others here) the OEM ones (Bosch also) seem to be the ones that work with least issues... that said, my last one lasted 6 months.

    You may also want to get VAGCOM (or another diag tool) connected to check faults as a faulty MAF will have thrown a fault code... you may have other issues too...

    <tuffty/>
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  5. LordNelson
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    LordNelson Member

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    [Oct 6, 2009]
    cheers fellas....i just need to get in touch with someone nr Wakefield with VAGCOM to do me that favour and i will look into getting an exchange OEM MAF from the stealers (i read that they do exchange units for about £70???)
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  6. LordNelson
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    LordNelson Member

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    [Oct 6, 2009]
    so if it runs on this default setting, what will it do to fuel economy?
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  7. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Oct 6, 2009]
    default is richer so worse on fuel economy generally
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  8. MintyS3
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    MintyS3 Works 60% the time, Everytime.

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    [Oct 6, 2009]
    Wonder how they are "reconditioned" as when you swap a new one for your old one its probably a reconditioned old one that was handed in previously with the same issue lol.
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  9. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    [Oct 6, 2009]
    I was told by Audi they can't get brand new ones and they are all 'recon' units... depends on the definition of 'recon' I guess

    <tuffty/>
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  10. Y83OLK
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    Y83OLK Hulk Smash!

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    [Oct 6, 2009]
    Just to note, Trade price is £52 for a gen Audi.
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  11. metricspaces
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    metricspaces Member

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    [Oct 6, 2009]
    What's the definition of a faulty MAF? Mine was producing way too low values for a standard S3. I replaced it. Then I was getting near enough the correct values i.e. much higher g/s values than before replacing it.

    I never had any fault code in VAGCOM before replacing my MAF. So, from what I've read and my own experience,I think you'd want to just go and log your MAF values. Then if they are too low, simply replace the MAF.

    Although having said that, I've read other threads on here that said low MAF values don't neccessarily indicate a dodgy MAF, and that the problem could be elsewhere.

    However, it seems to be such a common thing with the S3, that the chances of it being a dodgy MAF seem to be quite high, as opposed to it being something else.

    Another approach would be to find someone who is getting correct MAF values. Replace your MAF with theirs. Go log the values from their MAF in your car. If it's way higher than the values you were getting from the MAF you have, then you'll know that it is your MAF gone.
    Last edited: Oct 6, 2009
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  12. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Oct 6, 2009]
    where you have read problems "could" be elsewhere, yep for sure, but most of the time it is MAF as it is the most common failing part on these cars, then coil packs, then n75's

    start with the most obvious first

    in the USA MAF's are I believe service items now, such was the customer pressure on Audi of America to accept these were a factory problem.
    * i think*
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  13. metricspaces
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    metricspaces Member

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    [Oct 6, 2009]
    Not sure where I read this precisely. But I was just qualifying my response with a caveat i.e. these are just things I've read and my own unqualified experience :) . Sometimes it's hard to tell how qualified the opinion is behind a response - in my case it's just from things I've read and the little bit of experience from my own S3 problems.

    The point I was making about the MAF was that in my experience VAGCOM didn't show a fault, but my MAF was definitely not working correctly - i.e. don't rely on a fault code to see if you've a dodgy MAF. Log the data in VAGCOM on a run and see what values you get.

    Just because you've low MAF values doesn't neccessarily mean you've a dodgy MAF. But as you say, because it's such a common fault, the probability is that it's the MAF that is not working correctly, and for the relative cheapness of the part and 2 minutes that it takes to replace, it's definitely worth just replacing in my opinion.

    From the service history that came with my car, the MAF was replaced less than 4 years ago - just goes to reinforce the point about this being a service item!

    I replaced my MAF and that sorted out the cludgyness and muted performance, then replaced all four coilpacks...and it was pulling better than ever and running much more sweetly.

    Then got CC stage 1 remap with Forge DV and it's like a different car...puts a smile on my face now :) ... of course then there's the brakes to sort out, followed by suspension...not to mention my front windscreen just cracked...never ends :p
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  14. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Oct 6, 2009]
    stealers dont change maf's unless there is a fault logged.. grrrr, even tho grossly under reading. its forums etc where people can exchange relative measurements where you can gauge your own to. great resource.

    there are far more faults than reported by "The Computer" and its a sad day when dealers just plug in read faults, see none, and pronounce it healthy, even tho may have driven in on 3 wheels, oil pouring out of the engine, and spluttering like chain smoker on krak, but "The Computer Says No" - lol

    laughable except its often true..

    usual performance check is disconnect maf, drive it and if it feels quicker your old maf is on its way out.
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  15. Keeno
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    Keeno Spooly Spooly Boosty Boosty!

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    [Oct 6, 2009]
    What are the symptoms of a failing/failed n75?
    Went in for an MOT and I got a mass air flow code, so I replaced the MAF (I'd been meaning to anyway, lumpy idle among other things). So anyway new MAF but no real change in performance, slightly better throttle response if anything at all...

    Would a FUBAR'd n75 throw a code on VAGCOM?

    Pretty new to forced induction, so any pointers would be appreciated!
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  16. LordNelson
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    LordNelson Member

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    [Oct 8, 2009]
    Well, the simple test i did was just to unplug the MAF....the difference was very noticable. so, i have ordered a new MAF on trade for £50 (cant say no for that price). Stealers wanted £85. I also have new OEM spec NGK spark plugs to slot in. I will report results on Monday.
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  17. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Oct 8, 2009]
    n75 going on the fritz is usually a surging boost and or uncontrolled boost moments in my experience
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  18. LordNelson
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    LordNelson Member

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    [Oct 12, 2009]
    Ok, the results are in....New MAF and new OEM spec NGK plugs.

    ITS A NEW CAR!!!!!! why did i not make these changes sooner. feel like i have more horses, more pulling power and a bigger grin :D

    in terms of MPG, il have to wait until i fill up again and work out the ave over a full tank. Il be able to put V-power in now without feeling like ive been robbed

    Happy days :s3addict:
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  19. MintyS3
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    MintyS3 Works 60% the time, Everytime.

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    [Oct 12, 2009]
    Good going. Im thinking about renewing my maf and n75. Also my plugs need doing but was going to wait till next service.
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