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  1. #1
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    Another maf/thermostat/temp sensor thread

    Hi,

    I know this has been done to death, but I can't find a clear answer to the problems I'm having (S3 2000, APY engine):

    - Takes longer than normal to fire up from cold
    - Very juddery idle
    - ECU seems to have to recover from a stall whenever the revs fall to idle
    - Takes quite a while to get to 90 on fast roads but fairly quickly in town
    - Generally sticks at 90 once its there, will sometimes dip slightly on a long cruise
    - Noticeable turbo lag

    So far I've tried:

    - Garage cleaned the thottle body during service a week or so back (made cold starts better but not great)
    - Problem is there with/without MAF plugged in, but its worse unplugged (seems more drivable unplugged though)
    - I've had coilpacks go on it before and gave much worse symptoms, so I don't think it's that, unless there's one on its last legs?
    - Turbo was replaced 2-3k ago (the MAF did get caked in oil when it went but has been cleaned with contact cleaner since, which made quite a difference)

    I'm leaning towards a combination of MAF and temp sensor but appreciate ideas?

    Cheers
    Graham

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  3. #2
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    I have experienced the problems you've put down, haven't really got an answer more of what i did on those sort of issues.

    - Takes longer than normal to fire up from cold
    Lack of fuel in the system possibly, mine had issues and after trawling various posts there seemed to be an issue with the fuel filter i.e it is clogged up. So I changed it and it has been fine since. At the same time I had to change a couple of oil breather hoses and after inspection of the old ones they were full of oil crud and sediment build up which were partial blocking the hoses this may have attributed to it as well.

    - Very juddery idle
    This I thought was to do wth the TB and after a clean and an alingment the problem went away. Previously I changed the temp sender but this didn't help.

    - ECU seems to have to recover from a stall whenever the revs fall to idle
    Have you got VAG-COM to see if there are any DTCs?

    - Takes quite a while to get to 90 on fast roads but fairly quickly in town
    - Generally sticks at 90 once its there, will sometimes dip slightly on a long cruise
    Could be either the sensor or the thermostat or combination of both. Mine had an issue where it would get to 90 then drop down to the 70 mark and then fluctuate; replaced the thermostat and it has been fine since. Have you changed the temp sender, might be worth doing. ALso on the CC system you can toggle through the computer to check the temp as you are driving.

    - Noticeable turbo lag
    Could it be the DV? Is it through all gears and ranges?

    On the MAF you can do and exchange for 80 and the temp sender is 20, a new DV is 20. These are your 'cheaper and easier' options to start with, plus if you can VAG-COM it for free then you can hopefully deduce where to go next.

    Good luck
    Jester
    "On my second S3 and loving it. RS3 here I come!!!"

  4. #3
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    Thanks for the suggestions, a couple of quick questions:

    - Oil breather hoses - the engine was flushed after the turbo gave up so am I right in thinking these *should* of been checked and sorted then?

    - 'ALso on the CC system you can toggle through the computer to check the temp as you are driving.' - How? I don't remember ever seeing this in the manual or indeed finding it by accident!

    - Dump valve - when it releases pressure you can hear it do so in 3/4 short bursts rather than one continual one like I'm sure it used to - sound strange, or is that just the nature of a re-circ?

    - Turbo lag - seems intermittent, sometimes you can put your foot down and it will fly, other times it almost feels like it isn't boosting at all, in lower gears the boost generally seems to come in earlier than higher gears.

    I haven't got VAG-COM but my friendly local mechanic is a VAG specialist so I'm sure I can get him to hook it up for me - especialyl the amount of money I've spent there lately.

    Perhaps a trip to the stealers shortly too for the cheap options (temp sender and thermostat), although I'm hesitant to go as the S3 is still stickered up from Le Mans and due there in the next couple of weeks to have the roof bubbling sorted and don't want to give them any excuses! Or would the local Unipart have these bits?

    Cheers
    Graham

  5. #4
    jesters3's Avatar
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    Quote Originally Posted by grumbas View Post
    - Oil breather hoses - the engine was flushed after the turbo gave up so am I right in thinking these *should* of been checked and sorted then?
    They would not have checked these hoses norm would dealers as it is not a 'serviceable' part or check.. The Oil Breather hoses run around the engine block just feeding fumes here and there. Mine hadn't been changed for 6 years so had quite big build up, the only way I found these was because they were split and I had to get new ones. Otherwise I would never have known as it is not something you just whip off normally and have a look at

    Quote Originally Posted by grumbas View Post
    - 'ALso on the CC system you can toggle through the computer to check the temp as you are driving.' - How? I don't remember ever seeing this in the manual or indeed finding it by accident!
    Check out: http://www.wak-tt.com/tt/climatecontcodes.htm

    Quote Originally Posted by grumbas View Post
    - Dump valve - when it releases pressure you can hear it do so in 3/4 short bursts rather than one continual one like I'm sure it used to - sound strange, or is that just the nature of a re-circ?
    Pass I have the standard OE one still in the car. IIRC people say that if you have a 'fluttering' sound this is a sign of a fecked DV

    Quote Originally Posted by grumbas View Post
    - Turbo lag - seems intermittent, sometimes you can put your foot down and it will fly, other times it almost feels like it isn't boosting at all, in lower gears the boost generally seems to come in earlier than higher gears.
    Hmm, so foot down at any revs or gear sounds like mine, holds for a short while and then fires off, TBH haven't got a clue.


    Quote Originally Posted by grumbas View Post
    I haven't got VAG-COM but my friendly local mechanic is a VAG specialist so I'm sure I can get him to hook it up for me - especialyl the amount of money I've spent there lately.
    I would fecking hope so! May be worth it as well as do do some boost leaks tests if necessary to help out on the other issues.

    Quote Originally Posted by grumbas View Post
    Perhaps a trip to the stealers shortly too for the cheap options (temp sender and thermostat), although I'm hesitant to go as the S3 is still stickered up from Le Mans and due there in the next couple of weeks to have the roof bubbling sorted and don't want to give them any excuses! Or would the local Unipart have these bits?
    Temp sender you can do your self, on the Wak TT site there is a guide, plus you can get the parts from VAGPARTS.COM. For the Thermostat this is more of a job but you can still get the parts in from VAGPARTS.COM plus a few hours of work to sort: Poorly Thermostat?
    Jester
    "On my second S3 and loving it. RS3 here I come!!!"

  6. #5
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    Just remembered - I think at least one breather hose got changed on the service as it was split and showing an error code. Still waiting on the invoice to find out whats been done.

    'Fluttering' would be a good way to describe the DV noise! I'll have a search...

    Thanks for the help, looks like a weekend with the tools out...

  7. #6
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    Ideally speak to your garage and get a scan done and cleared before you start changing bits. Then after you've changed the bits get another scan done and so on so that you can see what has and hasn't helped.
    Jester
    "On my second S3 and loving it. RS3 here I come!!!"

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    Had a quick look this morning to try and get the part no off the temp sender and noticed the breather (pr bypass?) hose under the inlet manifold had come off!

    Also noticed the hose on the bottom of the DV wasn't on particularly well so fingers crossed that will solve that problem too.

    Can't wait to get out for a drive now....

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    Right, been for a quick drive, idle is back to normal at least!

    The DV seems a bit better but not great, so its either off to the stealers, or quite tempting to go for an upgrade, especially as its remapped.

    Using the climate 49c code the highest it registered was 85 with high 70s being the norm. The dash showed fairly steady at 90 most of the time but did dip to 85 now and again. None of the run was in traffic, although did keep getting stuck behind people insisting on doing 40 in a 60 - my pet hate!

    So is that the temp sender (which I notice is already a green one), or the thermostat?

  10. #9
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    fluttering

    Quote Originally Posted by grumbas View Post
    Just remembered - I think at least one breather hose got changed on the service as it was split and showing an error code. Still waiting on the invoice to find out whats been done.

    'Fluttering' would be a good way to describe the DV noise! I'll have a search...

    Thanks for the help, looks like a weekend with the tools out...
    The way i identified DV defective was if you rev the car on standstill up to about 3000rpm and just blip the throttle in that range from tickover you will hear the fluttering type sound which somtimes is described as pots and pans chattering together in sink

    Having now replaced my DV i can only just hear turbo when boosting a slight whooshing of air with window open and no noise when revving as described
    Hope this helps
    I have had breather pipes replaced that are underneath top cover on engine recently the only thing i noticed when changed my secondary air pump is a lot noisier on start up
    My car ran ok but was rather thirsty on the old juice 200 miles full tank standard 1.8 T atround town

 

 

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