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S4 BI-Turbo MAF problems

Discussion in 'A4/S4 forum(B5 Chassis)' started by darylpurnell, Apr 2, 2007.

  1. darylpurnell
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    darylpurnell My other car has two engines!

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    i have a 1999 S4 bi-turbo which i have been running for a couple months without a MAF connected (waiting for funds to buy a new one), as the car would not accelerate or rev above 3000rpm with it connected.
    i have just bought a new MAF and put it in the car and it runs just as bad as the origional one. i sent this MAF back because i thought it was faulty and they sent me a new one, but upon installing this new MAF the problem is still there.

    when the new MAF is connected and all fault codes removed from the ECU i took the car for a test drive (trying hard not to stall the not so smooth engine), when i got home no new fault codes were generated.

    The MAF has all the signals connected to it 12V 0V and 5V and i have buzzed the signal wire to the ecu and it was ok.


    I am stuck, has anyone else had a similar problem??, do i need to let the ECU adapt to this new sensor??

    thanks in advance for any replies

    Daryl
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  2. Beerzo
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    Beerzo Masa'warty 3200... Talk To Me!

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    Not sure if this would help but try disconnecting the battery for 30 mins ro so to allow the ecu to reset.
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  3. jcb
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    jcb Active Member

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    i should think running it without a MAF is inadvisable.
    would defo have to reset the ECU when changing something of that significance
    #3
  4. darylpurnell
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    darylpurnell My other car has two engines!

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    disconected the battery for an hour reconected and it is still the same.

    just tried clearing all fault codes first and will leave off for a lot longer, is there another way of reseting ECU?
    #4
  5. darylpurnell
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    darylpurnell My other car has two engines!

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    just had a better idea i put in my spare ecu which has been disconected from the battery for two months, still the same problem !!!

    Help
    #5
  6. Phantom_A4
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    Phantom_A4 Member

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    Sparkers might be mis-firing, i had a similar problem. Wouldnt idle right at all and the revs kept fluctuating betweent 1,100rpm and 700rpm. One of the sparkers had perished quite badly so replaced all 6 and ran just like new.

    Have you tried looking in to that?
    #6
  7. darylpurnell
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    darylpurnell My other car has two engines!

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    it runs sweet as a nut with the maf disconected (although lower power) but i take look at the sparkers tomorow. thanks
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  8. ZeroK66
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    ZeroK66 Member

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    Sounds really dodgy, you should really get this checked out by a specialist. heathchecks are as little as £45 and by the sounds of things would save you from a serious problem.

    See MRC tuning...
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  9. Turbo Lag FTW
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    Turbo Lag FTW Hate those none insured you know who types

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    When you connected your new MAF did you let the car idle for 10-15mins so the ECU could adapt to the new part?
    From what Ive heard any modification to the air supply inc sensors requires the car to idle for 10-15mins without any acceleration as to let the ECU adapt and correctly calibrate itself. Otherwise problems will arise as the ECU will struggle to deliver the correct amount of air to the ignition process.

    I could be wrong tho, just remember reading it somewhere on the american forums.
    #9
  10. sun and kath
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    sun and kath Member

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    Not sure if this will be your solution, but thought id mention it. I had the up and down idle and slighty rough running. I suspected the MAF and disconnecting it fixed the idle, but the car was a much rougher. - guess a limp home mode. Reconnecting the maf improved the running, but also brought back up and down idle and the car was still slightly rough and jerky.

    Turned out had to re syncronise the thottle (Drive by wire) with the acelarator. That fixed my car.
    #10
  11. pt7550
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    pt7550 New Member

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    pray tell how did you do that? mine has the rough idle and was told it was because of a new TB that was fitted and needed 'syncing'
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  12. ZeroK66
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    ZeroK66 Member

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    I would stop playing guess work and give MRC a call. I would expect they would be happy to offer some advice. Failing that a visit would be highly recommended.
    #12
  13. sun and kath
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    sun and kath Member

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    Hi Pt7550

    I used VAGCOM, i had the free shareware and an ebay bought wire previously. But to fix the problem i had to part with 100 dollars to RossTech and now have full VAG com. then I fixed my car in a couple of mins, after weeks of messing around.the instuction for re sync the throttle is on the ross tech web site - dead easy.
    #13
  14. mckay9uk
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    mckay9uk A4 2.4 30V PES Supercharged

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    Disconnect the battery negative for several minutes put it back on, switch the ignition on without pressing the gas or starting the car, and leave for five minutes, you may hear the throttle resetting itself, start the car without using the throttle and let it idle for five minutes.
    This is the manual way of ressetting the throttle this needs to be done when ever the battery is disconnected for a period of time. This can fix poor idling and hesitant acceleration. Let me know if this helps.
    #14
  15. mckay9uk
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    mckay9uk A4 2.4 30V PES Supercharged

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    full instructions here http://www.ross-tech.com/vag-com/cars/throttlebody.html
    #15

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