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Running lean!!!

Discussion in 'A4/S4 forum(B5 Chassis)' started by S4twiggy, Dec 13, 2009.

  1. S4twiggy
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    S4twiggy Fully Certified Detailer!!

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    [Dec 13, 2009]
    just a question or the brains out there, would a MAF that is on its way out or dead cause a car to run lean?

    went to the rollng road yesterday with the boys and found that
    my car is running 14.4 AFR instaed of 12.0 AFR and was told by bill(badger5) that its not good. some guy on SRS said his was the same and it was his MAF so.......
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  3. jcb
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    jcb Active Member VCDS Map User

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  4. S4twiggy
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    S4twiggy Fully Certified Detailer!!

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    [Dec 13, 2009]
    would it make it run 14.4AFR lean though?
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  5. jcb
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    jcb Active Member VCDS Map User

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    [Dec 13, 2009]
    depends how shagged it is.
    can make you idle at 400rpm or 400rpm if it is properly shagged.
    don't see why if it is telling the engine that you are only seeing 90% of the air you are actually seeing how it would know to compensate
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  6. Matt82
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    Matt82 Active Member

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    [Dec 13, 2009]
    it can make it run lean. a lot of thingss can cause a car to run lean including a lambda thats lying or even a simple air leak somewhere, a cracked manifold letting fresh air in

    i honestly dont really beleive our cars would have an afr as low as 12, if remapped 20vt lumps ive seen are anything to go by
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  7. S4twiggy
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    S4twiggy Fully Certified Detailer!!

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    [Dec 13, 2009]
    surely an engine thats running lean can lead to detonation which is wot i don want at all s this problem needs to be fixed, im trying to narrow it down so im not buying things i dont need, hopefully i can get he to see phil(PW) next weekend if he free so i can get it plugged in.
    #6
  8. Welly
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    Welly VX220 SC Driver :)

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    [Dec 13, 2009]
    I'd deffo start with the MAF mate - worst comes to worst you can always stick it on the Bay and get your cash back.... Desirable item! Unless you get one on exchange....

    Don't you know anyone who you could swap with for testing purposes?
    #7
  9. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Dec 13, 2009]
    I wouldnt want to see it any leaner than 12:1 on full bore...

    14.4:1 isnt right though, keep off the throttle unless you want to put speed holes in the pistons, and your also risking taking out the EGT sensors etc.
    #8
  10. ian52
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    ian52 2000 a4 1.8tqs-yellow

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    [Dec 13, 2009]
    Running lean + boost usualy ends with lots of £.
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  11. S4twiggy
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    S4twiggy Fully Certified Detailer!!

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    [Dec 13, 2009]
    i would mate but being so close to xmas i dont want to buy things i.e MAF untl i know exactly wot is causing the problem. i dot see how the MAF would be buggered after 4mnths although i have heard of them going after a few weeks but the car is nice to drive and the power is certainly there but wot would cause it to run lean. woud vagcom pick it up then? basically i need to get her into someone who knows wot they doing.
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  12. S4twiggy
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    S4twiggy Fully Certified Detailer!!

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    [Dec 13, 2009]
    so if i keep it under 70mph and dont take it over 2500rpm i should be ok for now until i can gt her booked into phil(PW) or bill at badger5 to get her plugged in and do some logs
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  13. Welly
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    Welly VX220 SC Driver :)

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    [Dec 13, 2009]
    Again, as said before, it depends how shagged it is. I had a MAF gone and it gave no error codes on VAG COM. I totally agree, and this is one of the big problems with Audis in general - fault finding can be a lengthy and expensive process. Realistically it's most likely to be the MAF of Lambda, or a vac/boost leak.
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  14. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Dec 13, 2009]
    i would pay more attention to being light on the throttle than trying to keep it under 2500rpm

    Feather throttle at 3500rpm is more friendly for the engine than a bootful at 2000rpm
    #13
  15. S4twiggy
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    S4twiggy Fully Certified Detailer!!

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    [Dec 13, 2009]
    i am light on the throttle so its cool
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  16. S4twiggy
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    S4twiggy Fully Certified Detailer!!

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    [Dec 13, 2009]
    tbh i dont think its MAF, i know wot my car feels lie with a dead maf so im not thinking it is that as the car is powerfull and drives lovely and hen the MAF was buggered it felt like a N/A 2.7 and when i changed it it went like a rocket and has ever since bt ill not be too sure until i get it plugged in
    #15
  17. ian52
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    ian52 2000 a4 1.8tqs-yellow

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    [Dec 13, 2009]
    Fuel filter blocked or fuel pump on its way out?
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  18. Geeman
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    Geeman Low Life

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    [Dec 14, 2009]
    Conversely... what are the effects of running too rich... like mine is?
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  19. Matt82
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    Matt82 Active Member

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    [Dec 14, 2009]
    excessive fuel consumption, bore wash, fuel in the oil (depending on how rich it is..) reduced performance
    #18
  20. Geeman
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    Geeman Low Life

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    [Dec 14, 2009]
    Arse. Better get it sorted then!
    #19
  21. jonnya
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    jonnya Member

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    [Dec 14, 2009]
    Mate, I'd just take it to MRC - they do a health check to diagnose exactly this sort
    of problem.
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  22. Matt82
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    Matt82 Active Member

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    [Dec 14, 2009]
    hes in south wales, arnt mrc pretty far up north?

    once you factor in petrol youre looking at £££ each time just to find out what the problem is...
    #21
  23. jcb
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    jcb Active Member VCDS Map User

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    [Dec 14, 2009]
    then book it round a road trip, dirty weekend, eBay delivery, business trip etc etc.
    Thats what I do.
    its worth it to see a specialist rather than spending £100 on something that doesn't sort it.
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  24. Matt82
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    Matt82 Active Member

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    [Dec 14, 2009]
    or do the research properly to start with so the £100 isnt wasted,

    id like a one stop solution to car issues, but what if they dont have the part in stock so you have to come back? its a bit impractical and youre lining their pockets big time on a car where is must be hard to justify that expenditure any more
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  25. jonnya
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    jonnya Member

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    [Dec 14, 2009]
    If you have access to VAGCOM then yes, you can do some of the research yourself. However, without access to the diagnostics and the ability to do sensor logging
    you are just guessing. I don't think 49+VAT is that steep to have someone who really
    knows what they are doing look over the car.
    #24
  26. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Dec 14, 2009]
    Depends how many miles you need to drive to get there...

    A vagcom cable costs a tenner from ebay, and will allow you to see what the ECU thinks the problem is.

    Its also far to easy for a "specialist" to say "aye mate, your EGT sensors are away, but that will have been caused by the airflow meter and you need new coolant sensor too, plus the sprocket flange and we'll change the lot for 5 million pounds"

    I'm not saying they will, but i'd be taking a look myself first. If its lean, either the lambdas are broken or the AFM is reading wrongly, there really isnt many other options.
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  27. Matt82
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    Matt82 Active Member

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    [Dec 14, 2009]
    yup, that about sums it up.

    getting them to diagnose it will cost £50 a pop, and what have you learned? you definately wont be forgetting the pin number on your credit card in a hurry.

    youll be lining their pockets and perpetuating the myth that these cars are a royal bugger to live with, further destroying their already comedy resale values. on top of that their is the moral issue youd have spending £££ if not ££££ on the upkeep of a car thats only worth £3k-£5k etc
    #26
  28. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Dec 14, 2009]
    The problem is that because they're more of a prestige car, less DIY happens.

    We've been trying to track down an odd throttle cut issue on craigs car since he baught it.

    If you take a vagcom log of a full throttle run in 3rd, you can see the throttle go to 100%, then once the RPM's get to 4k ish, it pulls the throttle back to around 50% and stays there until the redline.

    We posted up logs and suchlike on RS246 (i think), and most of the responses were basically "get a health check". I tried pointing out in the thread that all MRC would do is exactly what i've done, i jsut needed some pointers as to why it would be cutting the thottle. Someone said to log boost request and actual to see if it was overboosting, which didnt work on craigs ECU due to it being very early. One of the MRC guys even posted on the thread to say something along the lines of "yes that ECU is pre-C suffix so doesnt do any boost recording" but not even a snippet of help for the problem we had.

    Afaik the problem is still there, unsolved.
    #27
  29. S4twiggy
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    S4twiggy Fully Certified Detailer!!

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    [Dec 14, 2009]
    ideally i would love to take it to MRC or acompany like it to get a health check but as im in south wales a trip to banbury from where i am plus costof health check would be over £100 so thats out the question at the moment. im not going to just buy MAF's, lambda's or sensors just to see if it cures the problem so im going to try and get someone to do some logs for me and sensor readings to try and narrow down the problem and wot it needs to cure it, if someone is competent wth using vagcom then they would do exactly wot a specialist would do, id love to get the car pressure tested so MRC would be a great call but i just cant justify it so close to xmas.
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  30. jcb
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    jcb Active Member VCDS Map User

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    [Dec 14, 2009]
    pressure testing is easy and not worth getting someone who charges £40 an hour to do it.
    I agree you need to get as many things checked out before you start throwing good money after bad.
    there must be some VAG chaps in South Wales somewhere
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  31. S4twiggy
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    S4twiggy Fully Certified Detailer!!

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    [Dec 14, 2009]
    hopefully i can get mark to have a look at it for me, ill pay him for his time so fingers crossed mate. if only i had a pressure testing kit, some guy in work is making e one but thats been for like 3 mnths now so no joy there
    #30
  32. jonnya
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    jonnya Member

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    [Dec 15, 2009]
    Really? The free VAGCOM version now lets you log all the groups and interprets all
    the fault codes for you?. As far as I am aware, only the full version is of any use for
    diagnosing this type of problem.

    The "specialist" you anecdotally refer to sounds more like a dealer to me ;-).
    I recommend MRC because they have found problems that nowhere
    else had a clue with. For example, they found that the vacuum piping around my fuel
    rail had not been welded properly from the factory (i.e. it had a vacuum/boost leak
    from new). There are many more reasons than what you state for why the engine
    may be lean (intermittent fuel pump fault, boost leak, injector fault)
    #31
  33. Matt82
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    Matt82 Active Member

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    [Dec 15, 2009]
    leak in a hardpipe... a boost leak kit would find that too. all it would require would be for the user to be able to hear the leak

    sure they will have a lot of experience with the engine, the main benefit of that will be theyll be able to tackle jobs faster due to experience, but when it comes to diagnosing, provided you have the time you can achieve the same as they can

    i see it as a complete waste of time driving hundreds of miles just to get someone else to diagnose a problem for you, esp on something old/low value like a B5 S4.
    #32
  34. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Dec 15, 2009]
    Free vagcom will give you the fault codes, ok it doesnt translate them all into english but all the codes are on rosstechs site anyway so it only takes a few seconds to look them up.

    I think the free version lets you log or at least view single items, but yes, you need a licenced version (which is only $100) to do full logging. I'd much rather spend my money buying a VCDS licence than paying for a one off health check, because as i've said ALL the information available to the specialist is available to you once you've got your vagcom setup.

    My point with the specialist was that should they inform you half the sensors need replacing, you only have their word for it. I'm sure some of them are streight up enough not to lie, but do you KNOW that all those sensors are duff? No. I've heard them recommending AFM replacement when an EGT sensor dies, but without putting the car on a dyno and looking at the AFR, you dont actually know if the EGT has just packed up because its 12 years old, or because the AFM is actually dead.
    #33
  35. Matt82
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    Matt82 Active Member

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    [Dec 15, 2009]
    exactly. if you cant figure it out, search on a board on the ross tech site.

    as for taking people's word for it, i did think that at the start after all the horror stories about having to have every sensor changed. mine are all functioning and giving plausible figures after all this time.

    the reason i dont touch garages is because of little scams like that
    #34
  36. S4twiggy
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    S4twiggy Fully Certified Detailer!!

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    [Dec 15, 2009]
    thats the reason i want someone i know to look at the car for first, if they then say that they cant do it and cant find the problem after trying hard to do so then a trip to a specialist it would have to be.

    jonnya i know wot your sayin about MRC and i know wot they do so you dont need to preach them to me as i want the car in there nxt year for some work done i.e custom remap, milltek etc as ive heard very good stories about them, the only thing i cant justify is the petrol costs to get there and back and pay for the health check. if this was in feb or even january i would be straight there but i have xmas to sort out, my tax is up 31 dec and my MOT is on 15th january so its a tough one for me this month.
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  37. S4twiggy
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    S4twiggy Fully Certified Detailer!!

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    [Dec 15, 2009]
    if i get the rosstech license, does it come with a lead aswel as the software? i have a cheap ebay led and vagcom but it aint easy to use so i cant be bothered with trying to get it to work so im looking to get rosstech license in the new year but want to know wot comes with it??
    #36
  38. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Dec 15, 2009]
    two options.

    1) genuine rosstech cable which comes with a licence for £250ish
    2) get a licence for your existing ebay cable for $99

    I dont see why its "not easy to use", the real rosstech lead isnt going to be any easier?

    I'm an advocate of the $99 licence as it will do anything you want to do on a B5, and rosstech will give you a $99 discount on the real lead if you ever do want to upgrade to a genuine cable in the future.
    #37
  39. jcb
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    jcb Active Member VCDS Map User

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    [Dec 15, 2009]
    just bought one, $229 IIRC (plus the usual £20 to the DHL nazis!)

    my ebay lead was a bit tempremental, didn't like the port, didn't like the software version, could find teh car, didn't want the ignition on, didn't want the ignition off, lost signal halfway through etc etc.

    new one is plug and play
    #38
  40. S4twiggy
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    S4twiggy Fully Certified Detailer!!

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    [Dec 15, 2009]
    like JCB said, the lead doesnt like the port when try'd on my car, it worked on my old mans B5 2.4 but only after guidance from a guy on SRS, when i try it on mine it comes up sayin summin about interface so i thought bugger it. rosstech is the way to go. think ill get the lead and license at the same time, no excuses for not wrking properly then.
    #39
  41. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Dec 15, 2009]
    I've never had an issue with mine, and used it on various cars. I'm sure Mark and Lee both have ebay cables and craig has one too without any problems.

    The only connectivity advantage the rosstech cable gives you is that its a native USB interface. The ebay cables are serial, but use a USB to Serial convertor, and in some cases the port number the PC allocates to the convertor changes, usually when you use a different physical USB port on the PC.

    IMO its not worth double the price, for a B5 anyway, however if you feel its worth the expense then go for it. At least with the real cable you'll have support from rosstech for the hardware too.
    #40

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