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  1. #1
    coyote's Avatar
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    1.8T Boost Problem

    I have started getting a loss of boost. This only seems to happen occasionally in 3rd or 4th gear when I floor it from around 1800 rpm, the car pulls fine up to 3000 rpm then seems to stop boosting for around 1 second (feels like the car is being pulled back) then it boosts ok right through the rest of the revs.

    Any ideas?

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  3. #2
    evilscotsman's Avatar
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    could be you've got a flaky dv or n75 boost control valve? I wonder if its hitting overboost briefly and dumping then continuing.

    It could also just be an old fashioned flat spot caused by plugs or coilpacks, just chucking some ideas in
    B4 TDI - old skool project / daily driver...if it ain't broke, it's probably an Audi...


  4. #3
    coyote's Avatar
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    Cheers Scotty. My car is due a service very soon so as they need doing anyway I will pick up some plugs from Halfrauds.

  5. #4
    evilscotsman's Avatar
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    no probs mate, other thing to think about - is it after using cheap unleaded it does it? Mine "pinks" badly on normal unleaded 95 under load and the power sags - but on 99 super from tesco it doesnt do it, modern cars will retard the timing if pinking occurs.

    I think if you were hitting overboost you would probably get a CEL light, even a flash of it.

    Maybe worth getting it scanned for codes? My fav guess at the moment tho is a plug or coilpack breaking down under pressure.
    B4 TDI - old skool project / daily driver...if it ain't broke, it's probably an Audi...


  6. #5
    J7USS's Avatar
    Shuddup Foooool!!

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    Evil, how could you put 95 in your car , dont it drive rough??
    Mine always seems to sound raspy when Ive had to use it..
    Ever since I used it in the 4star days, Im para to put it in any of my motors. My scooby sounded like a talbot when I had to fill up on 95 during the fuel crisis!!

    anyway where was I...

    I wonder if the DV like you say is leaking. The more boost you putting through it the more pressure hence if its split then it just gives way under heavier boost.
    What do I know...
    The last time I had a similar problem, I changed Both the DV and N75, gave all the pipes a good seeing to, checked everything and it was ok after that.

    Coyote, is there any Hissing sounds at all under boost?
    Have you tried driving with both front windows down, stereo off, fixed up and looking sharp!lol listening for any unusual sounds from the bay??
    Might be worth a try, thats how I knew there was something wrong with mine.

  7. #6
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    Hi,

    Im getting somthing similar. on a quite morning, with the drivers window open, when I leave the end of the road I can hear the turbo making a twittering noise under accelaration. Seems a little flat as well after the initial boost cuts in......other turbo cars i have heard or driven seem to have a smooth boosting sound. sorry thats the only way i can think to describe it!...have had the vag-com on it and not showing any faults
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  8. #7
    evilscotsman's Avatar
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    j7uss I can only get crap 95 at our local petrol station but i usually fill up on nothing but tesco 99 super cos its the best. yeah it does sound tinnier on 95 and it pinks.

    And aye guys the dv is mechanical so the ecu cant monitor it. low boost wouldnt be reported as a fault like overboost. A faulty N75 valve can I suppose pull the plug when it shouldnt but the likely culprit is the dv. The twittering sound will be the diaphragm leaking and doing bird impressions lol
    B4 TDI - old skool project / daily driver...if it ain't broke, it's probably an Audi...


  9. #8
    coyote's Avatar
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    I use V-power 90% of the time and it is in my car at the moment so it can't be a fuel issue.

    As soon as it stops raining i'll "fix up, look sharp" and blast around the local area listening for the birdies under the bonnet.

    I think i'll change the plugs first thing tomorrow as they are needed and if that doesn't change things depending on cost its a trip to the stealers (2 miles away) or vagparts (30 miles away) to pick up the valves.

    What dv should I be looking for 710N?

    I still love it even though its not running properly

  10. #9
    evilscotsman's Avatar
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    yeah 710n but there are revisions of it, "J" i think is the high boost one - j7uss can say for sure as hes changed his
    B4 TDI - old skool project / daily driver...if it ain't broke, it's probably an Audi...


  11. #10
    coyote's Avatar
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    Changed the oil and plugs, gave the boost pipes a good check over and refitted and tightened all the clamps up.

    Car is running like a dream

  12. #11
    evilscotsman's Avatar
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    cushty
    B4 TDI - old skool project / daily driver...if it ain't broke, it's probably an Audi...


  13. #12
    J7USS's Avatar
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    Good stuff. Its best to keep checking the pipes aswell because they easily come loose, even after a good tightenting.
    Glad you got it sorted though, nothing better than a positive result.

  14. #13
    "Stick a V8 in it!"

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    Your car should not be "pinking" audibly at all...

    There is a knock sensor fitted to the engine and the engine management will retard the timing waay before any pinking becomes audible to the naked ear.

    Been out in my bros S4 doing some VAGCOM logs and it was pulling 7-8degrees out of the timing at certain points of the rev range due to the 95 oct fuel that was in it, but it still wasn't audible at all, and the difference in performance really wasn't that noticeable.

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  15. #14
    J7USS's Avatar
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    Mine definatley sounds different with crappy 95 and the performance was definately noticable.
    Its even slightly noticable between Vpower and BP ultimate.

    My local shell had a Vpower day last friday and it was same price as Unleaded 88.9p ltr so I filled her right up. Apparently they are doing it again soon. Even gave the Mrs Polo a good fillng up!

  16. #15
    coyote's Avatar
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    Aaaaarrrrrgggghhh!

    Driving along and then a sudden loss of power followed by a flashing engine management light... I tried to keep calm and carried on until the next layby. Car was sounding rough so bonnet up, screwdriver in hand I took off the engine cover and pulled the coils out to check one by one. Found the culprit number 3.

    Now I have a hard decision. The Audi stealer is 3 miles away so I could go there for 8.30am to pick up a coil pack and get to work late. Or go to Vagparts on a long lunch break for a cheaper part, but the temptation to get the credit card out for some door blades maybe too much!

  17. #16
    J7USS's Avatar
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    ...its coilpack fever!!!

    Go on mate, treat yourself.
    Why Not...Just dont tell the mrs and jobs a good-un

  18. #17
    coyote's Avatar
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    Thanks for the support J7USS

  19. #18
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    Time for a update:

    After the 1st coilpack died and was replaced the 2nd died immediately, changed that then the 3rd died? When I spoke to Vagparts I was told that they had just got off the phone to someone who had just had 3 blow on them at once, they also stated that as soon as the temperature drops they sell more coilpacks so it must now be the season for them. I also managed to walk out of Vagparts without the door blades, it was a close shave though (maybe after xmas)

    My car now has clean oil, new filters, new plugs, new coils, new brakes, new tyres, ive also ran van-com and cleared all old faults and the car is now once again running perfectly... So what can go wrong next?

 

 

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