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S3: Power 100% but then suddenly at around 80% (AMK)??

Discussion in 'A3/S3 Forum (8L Chassis)' started by Dennis Moeller, Jan 11, 2009.

  1. Dennis Moeller
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    Dennis Moeller Member

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    [Jan 11, 2009]
    Hi peeps

    Ok, I have this annoing issue with my 2001 AMK S3.

    If I start the car (cold or warm engine doesn't matter) the power delivery feels normal (let's call it 100%). Then I arrive at the destination and turn the engine off. If I then start up the engine again it has clearly lost some power. Car feels normal, its not juddering, it doesn't misfire or anything, it has turbo boost...It's totally normal except it feels like it has less power (around 20% left, this is of course different to measure but roughly). It simply feels a little dull!?

    It can also be the other way around. Car is started and it feels slower (a little slow, at around 80% of it's best) and then the next time i fire it up it just fly. Like its on stereoids.

    Now I know this sounds like it's just me and that maybe the weather plays a part but I have now had two friends drive it and they first didn't believe me. The first one I just said; hey try my S3 and see what you think (I told him nothing about the issue with the power)! We then drove for half an hour and he thought it was pretty normal (powerwise), meaning; yeah this is an S3 with 210hp and it drives good and normal. I then told him about the power issue, He kinda laughed but I told him to take the key out of the ignition, wait one minute and then start the engine. We drove back and the first time he floored it he went...; Oh my Fecking God...It's different. More grunt, more eager, more power. Like it's been remapped or something...We were both baffled by the reality...
    We took out a reading with VAGcom but it showed nothing, no fault codes, no sign of engine beeing remapped.

    Next friend to try it. This time I told him about it and this time it was the opposite way around as I drove to a place to meet him, turned off the engine while we smoked a fag...car feelt really good he thought, it drove really well for having only 210hp...I asked him to pull over and turn off the engine, and then start it up...we drove some more and as soon as it were safe to floor it he just couldn't believe it. It was definately slower than before?!?

    Cutting it really short; what is going on? Can you help me with this problem. Have anyone experienced the same or even remotely the same?
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  3. S3 Paul
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    S3 Paul Well-Known Member Regional Rep

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    [Jan 11, 2009]
    Hello sir.
    Erm, Ive had a few problems like this sir, When i first got my S3,
    I have a few ideas for you t try...
    first check that the diverter valve is working and the pipe work to it is in good order.
    Check that the 2 pipes that go to the top metal charge pipe are not split or starting to split.
    check that the breather pipe that comes from the cam cover isnt overly soft or split.
    now the fun bit...
    if non of the above helps you should check all the vacum pipe work on the car as a small leak will make the car like a woman... some times great... some times off.
    Start with the engine cover off ( the plastic one) and check the pipes that go to everything boost related are in good order. Also the N75 valve may be playing up or the other valve that is clipped to the top of the cam cover.
    I hope this helps. under the inlet manifold there is alot of small rubber vacum hoses that can and do split over time. its a pain to get to them but worth it in the long run. Take of the cover and suport bracket taround the dipstick to help you see these.
    And finaly the throtle valve may want cleaning and reseting ,

    Let us know how you get on .
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  4. Dennis Moeller
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    Dennis Moeller Member

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    [Jan 11, 2009]
    Thanks for the reply-

    Ok, assuring to know it's not me going bonkers. I will check all the hoses as you described. Two things I know; the car had all the vaccum hoses replaced by previous owner (done at the dealer) and also the MAF was replaced (those things initially led me to believe it was remapped). The second thing is that there's a Kimmit Racing DV that seems to be turned upside down compared to pictures of the OEM DV...But people tell me they could be installed both ways as it's only a valve and it will work no matter which way it's installed?! Could that be some of the answer - is it installed incorrectly?

    The throttle valve was also reset when they exchanged the hoses but I don't think the shop cleaned it before resetting it.

    If the N75 valve were faulty wouldn't it come up as an error when we diagnosed the engine?

    Ok, I'll clean the Throttle valve and inspect all the pipes and hoses. And try and install the DV "the right way"...

    Again thanks!
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  5. NHN
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    [Jan 11, 2009]
    Yeah do a TBA after cleaning as over time it can get some black **** around the gap of the flap which doesnt allow it to close properly, check as above all hoses but doubt split as does when its cold & pipes only really show small splits when warm as cold rubber is fairly hard(no jokes) & also if you can drive then stop then drive with more power also with less power then split would be same at all times when warmed up tbh not intermittant IMHO, check for any **** in the maf, check airbox for any leaves, check the dv is working prop by removing & its spring is working ok, even change DV makes differences aswell

    If its mapped it could also be the intake pipe from airbox to turbo collapsing & the upgrade by forge is much harder & better pipe tbh & doesnt collapse, this can cause intermittant issues like loss of power cause if you have an increased vaccum in the pipe then of course it collapses pipe & you get less air flow which of course powers down aswell, just ideas as seen his before

    But overall check with Vag for any codes being thrown
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  6. S3 Paul
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    S3 Paul Well-Known Member Regional Rep

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    [Jan 11, 2009]
    I had the turbo intake pipe problem too. But when it "collapses" it feels more like lag than a loss of power.
    The vacum leaks i mention are there all the time but as the engine moves it takes time to log the fault on the ecu. i would try a stock dv valve or check the one you have but would definatly fit it the same way round as the stock one.
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  7. Dennis Moeller
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    Dennis Moeller Member

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    [Jan 11, 2009]
    Thanks mate. That made sense cause if mapped the inlet pipe could be playing up...Is it a difficult job to change it to the upgraded Forge?

    And no fault codes come up...tried two times.

    I will refit the DV the way the OEM is installed, ie. the valve is "standing up" not "laying down" as mine are...

    To both; cleaning the TBV...anything to be aware of regarding the valve itself? This is motorized right, so no movement is good yeah?
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  8. NHN
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    [Jan 11, 2009]
    Not difficult at all, just make sure you get the bottom half onto the turbo properly & make sure its in the correct position for the top connections then fix the jubilee round the turbo end & tighten thats all & top connections are damn easy tbh IMHO

    If it has play just by using a small finger than this could be an issue on the TB, but if you have to force it to move even 1mm then its fine, but clean the **** of it anywhere so balanced well, make sure there's no visible gap when its closed, then do your alignment with vag, but as with all this just take time & patients dont be heavy handed, as Vin Diesel says "Got nothing but time baby, nothing but time" lol

    If no codes thrown then doesnt sound to serious IMHO from when I had my S3, check no pipes have been pinched cause I had that happen after some numpty fitted some bits back after cambelt service, needless to say fixed it myself

    but amazes me how some of these guys manage to become a mechanic(sorry, vehicle technician) lol, its like calling a medical consultant a doctor over here, FFS they're mechanics & they're doctors, simple as that, lol, "what did you train to be, doctor, then whats problem being called a doctor", lmao
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  9. Dennis Moeller
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    Dennis Moeller Member

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    [Jan 11, 2009]
    Yeah, the stuff's been changed at the authorized dealership and show up in their registry but I don't know if they did an ok job tbh. Every hose is secured with these:
    [​IMG]

    Is that correct to use these...seems a bit amateurish but this is my first Turbo car with "delicate" technique so I'm a bit of a newbie on these engines...
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  10. NHN
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    [Jan 12, 2009]
    Nah its sprung loaded so it shouldnt be a problem & you can push it open to clean, just make sure its not actually loose when it flips back into closed position, well its supposed to be closed so if its open at all without pushing it then this could be sign of an issue but clean it up & see what you get afterwards, I had mine for 7 years & cleaned it once, never had one issue

    Nah jubilee clips are very good tbh & for me they've been very reliable so wouldnt worry about them at all, but check everythings tightly done up ok, be careful not to tight where pipes get squashed or hoses get cuts from overtightening
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  11. Dennis Moeller
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    Dennis Moeller Member

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    [Jan 13, 2009]
    YEAH PROBLEM SOLVED :yahoo:

    Had a go at it last night and I started off by inspecting all the hoses on the upper part of the engine. No faulty hoses, no cracks - just good healthy rubber everywhere. Then I decided to turn the DV to it's OEM upright position and then....

    I could nearly take it out without using force. The jubile clips weren't even tightened. I took it out and installed "the right way" and made sure everything was tight and good...took a testdrive and something wasn't right. Back in the shop, reversed the position of the DV and a new testdrive..Nooo power at all. Like driving an NA 1.8...something must have been wrong and now it was totally wrong, I thought appearently. Suddenly I discovered that I forgot to attach the switch that sits right to the left of the MAF switch (Neeewb)....in with the sucker and another testdrive...

    BAM, power all the way, really eager up through the rev range and a big smile appeared on my face. Turned the engine of, took out key and hit it again. The same; engine and car just took off. Drove around small roads for an hour just having a blast and emptying the gas tank. Did a final check, turned it off and started it again. Full power again....

    So, luckily the problem were solved. I did notice a slight hesitation or two and a very small hickup when boosting but as I've read in numerous other threads; thats another story...probably the N75, the TBV needs cleaning and a reset...or another switch needs replacement here and there.

    BTW just had the car in for the service with belt changes etc. and everything was replaced. Hadn't had time to do it myself and didn't feel comfortable enough - I'm sticking with suspension, brakes and cosmetic appearence, thats my field. Fluids, filters, sparkies, Haldex lubed up, waterpump, belts etc. etc everything new. Wonderful. No fault codes except one for a switch on the thermostat that needs replacement.

    Happy camper now....THANKS GUYS...Owe it to you :friends:
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  12. NHN
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    [Jan 13, 2009]
    Cool man, its always the simplest things huh, so to check is the DV still upside down?

    Got any pics as I'm intrigued
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  13. Dennis Moeller
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    Dennis Moeller Member

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    [Jan 13, 2009]
    Yeah the DV is kinda lying down compared to OEM standing up...I can take a picture and show you...or because it's freezing cold outside make a drawing soehow...give me a few minutes then...
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  14. Dennis Moeller
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    Dennis Moeller Member

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    [Jan 13, 2009]
    Here you go..1 masterpiece made in a hurry...(Ok, let's forget about it yeah)

    Hose outlet (or is it inlet?) nummer 1 and 2 as I would say they are supposed to be installed. The DV is an upright position.

    Mine is installed the opposite way around. "Hole/hose" no.. 1 goes to maf/air...and no. 2 goes to the turbo..

    [​IMG]

    The way mine is intalled (opposite the picture) it makes a faint screeching sound...You can hear it really clearly if you're outside the car and it kinda irritates me that people look at me like I'm some nutter with a Volvo 240 big turbo...

    Will a brand new Forge 007 make any noise...
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  15. Dennis Moeller
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    Dennis Moeller Member

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    [Jan 13, 2009]
    Aaargh...I made a mistake...switch the numbers on the drawing! 1 should go to 2 and 2 should go to 1...THEN you have my drawing of what I think will be the OEM position of the DV

    And mine is the opposite way around...Yeah....eeehh...get it?
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  16. NHN
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    [Jan 13, 2009]
    well for me my s3 was as above in the image, if you have it round other way then I can only say it isnt as per spec of the car & if your dv is built differently then maybe it will need reversing round, but I'd get a forge as I had mine for ages & never had an issue & fitted oem properly, but I can recall now I had a sudden loss of power in london one day & it was just purely a pipe come loose & yeap it was the damn jubilee clip that wasnt tight enough, god that day I really did **** my pants as thought its the turbo, lol, reconnected pipe & damn she went even faster :racer:
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  17. Dennis Moeller
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    Dennis Moeller Member

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    [Jan 13, 2009]
    Hehe...you do get a sweaty moment when it happens...Forge is on the A-List.
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