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S3 losing power/ not boosting

Discussion in 'A3/S3 Forum (8L Chassis)' started by fluffsri, Mar 14, 2011.

  1. fluffsri
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    fluffsri Member

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    [Mar 14, 2011]
    Right then, some may have read before Ive had lots of trouble with this car. It now has a reconned engine and a refurbed turbo, the turbo actuator was fecked and the turbine housing was cracked.

    Its been running great since all the work was carried out but and old fault is back, we thought it was a sticky wastegate but its now doing it with a new turbo?

    Symtoms are driving along on a constant throttle and you fan feel the torque drop! revs and speed dont change but you can feel the omph go and it wont pull past 4000rpm, no EML. When this happens and you put your foot down its flat, no power, the turbo whistles but sod all else.

    The thing is,if you drop down a gear and give it some itll pull hard all the way to the red line (I only went to 6500 but Im guessing itll keep going)

    Any ideas guys as Im at a total loss?
    #1
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  3. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Mar 14, 2011]
    Do you get a fault code when scanned with VCDS? If so can you post up the error code.
    #2
  4. fluffsri
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    fluffsri Member

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    [Mar 14, 2011]
    No EML so no codes stored, last time it was scanned no faults apparent.
    #3
  5. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Mar 14, 2011]
    I have a similar problem at the moment that I suspect might be the cat. I think the cats are breaking up and this is restricting power. Some days it's worse than others.

    I used VCDS to diagnose the post cat lambda sensor and it suggests that the cat is damaged, I'm hoping Bill will be able to confirm this for me when I see him on Saturday.
    #4
  6. fluffsri
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    fluffsri Member

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    [Mar 14, 2011]
    Vik has been complaing of a buzzing noise, I thought it was an exhaust heat sheild loose but it could be the cat, the noise eminates from gear lever area
    #5
  7. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Mar 14, 2011]
    Do you have VCDS? I can tell you how to read the lambda sensor and what to look for if the cat is damaged.

    With mine the sensor is suggesting cat damage but the MOT centre said that the car was running fine 4 weeks ago when I MOT. I will let you know what diagnosis Bill comes up with on Saturday.

    If it is the cat I have found this on eBay:

    AUDI S3 1.8 99-03 Catalytic Converter Cat on eBay (end time 16-Mar-11 10:23:48 GMT)
    #6
  8. fluffsri
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    fluffsri Member

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    [Mar 14, 2011]
    I dont have VCDS but I may know a man who does. Ill give him a shout at the weekend.

    The fault Ive mentioned doesnt happen all the time, is yours the same?

    Keith
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  9. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Mar 14, 2011]
    If you check the voltage of the post cat lambda with VCDS it is supposed to be fairly stable at idle. If the voltage is fluctuating then it suggest cat damage. Mine is all over the place but I have seen a healthy S3 lambda so I know mine definitely isn't right!

    I'll dig out the guide tomorrow.
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  10. fluffsri
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    fluffsri Member

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  11. fluffsri
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    fluffsri Member

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    [Apr 1, 2011]
    This has been with an Audi specialist all week (hes not taken that long to find it, hes doing in between other jobs). He has run the car several times but couldnt replicate fault.He has checked everything and found the thermostat had siezed so he couldnt check the settings on the road properly as the diagnostic system need temp to be over 85 degrees, car was settling at 80.

    With the diagnostic kit working properly it showed the MAF was knacked. With the MAF replaced the car was breathing properly, he could maker it loose boost to order. Fault code was a P0155 IIRC, turbo over boost. Points to N75. Slaved a new one in and same fault.

    Hes now ordered a manual bleed screw with spring and ball and hopefully this will cure it. Its the ECU that seems to be sending a dodgy signal to the N75 valve. Thats being fitted next week. Will let you know how it goes.
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  12. fluffsri
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    fluffsri Member

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    [May 11, 2011]
    Westle did you sort yours out?

    I still have the fault and all it says is over boosting. It only happens now and again though so were living with it. At a loss with it to be honest.
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  13. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [May 11, 2011]
    Hi mate. My irratic lambda readings turned out to be due to the ****e remap I had! It was running massively lean and I think the post cat sensor was going mental about it. I changed map to Revo and now it's sweet as a nut.

    The over boost error you have, does it say "maximum boost limit exceeded"? I also used to get this error from time to time and it would put the car into soft limp mode. I fixed it by fitting a brand new N75 valve. Not seen the error since.
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  14. fluffsri
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    fluffsri Member

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    [May 11, 2011]
    Good stuff on curing your fault. We had the map checked as well in case it had been mapped before we had it, its a totally std map. Tried a brand new N75, made no difference.

    Its doing as you said though, soft limp with no EML. Fault comes up as you say.
    #13
  15. cecilthesausage
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    cecilthesausage ...It's Never Finished...

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    [May 11, 2011]
    I have a cat if you think this could be the problem
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  16. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [May 12, 2011]
    Have you checked all the things it says to check on the Ross-tech website when you search the error code? Can you remind me what the code number is and I'll dig out the info.
    #15
  17. AARON77
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    AARON77 Active Member

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    [May 12, 2011]
    I love my revo I think it's great map :)
    #16
  18. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [May 12, 2011]
    My car hasn't thrown 1 error code since I switched to Revo. The old map (who's name I shall keep quiet) used to through stuff up all the time and made my lambda sensor thing the cat was damaged! What sort of a map is that!
    #17
  19. fluffsri
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    fluffsri Member

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    [May 13, 2011]
    I cant remeber the code now. Were sure it isnt the cat as all readings were well within limits. Ill look on the Ross tech site and see what it says. Whats a Revo map?
    #18
  20. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [May 13, 2011]
    Are you being serious, youve not heard of Revo? They are one of the biggest names in the remapping Market.
    #19
  21. fluffsri
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    fluffsri Member

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    [May 13, 2011]
    Nope never heard of them. Not mentioned in my usual Vx circles.
    #20
  22. blued
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    blued Member

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    [Oct 4, 2012]
    I know it is an old thread but did you resolve this? The same problem has just started happening to my '99 S3. It has been remapped but I'm not sure who by, the previous owner said it was a 240bhp remap and it normally boosts to about 20 PSI. Now it drops off like you describe. The car hasn't been used much for the past month or so, so maybe that is a factor. The only other mod I know of is a forge dump valve.
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  23. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Oct 4, 2012]
    The problem described by the original poster sounds like the car is going into "soft limp mode". This is when the ECU detects a problem, normally exceeding boost in this instance and it makes the car run on actuator pressure only which is 6psi. It's a "soft" limp as you can clear it by turning off the car then back on again.

    You really need to scan the car to see what is happening.
    #22
  24. blued
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    blued Member

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    [Oct 4, 2012]
    Yes soft limp mode is exactly what it sounds like. Can I scan it with VCDS lite or do I need a full version? I think someone I know has an old version of VAGCOM, he was able to read the fault codes on my Mk4 Golf.
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  25. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Oct 4, 2012]
    Lite should be fine. Give it a go and let us know how you get on.
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  26. blued
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    blued Member

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    [Oct 4, 2012]
    Here are the fault codes -

    18010 - Power Supply Terminal 30: Voltage too Low
    P1602 - 35-10 - - - Intermittent
    16514 - Oxygen (Lambda) Sensor B1 S1: Malfunction in Circuit
    P0130 - 35-10 - - - Intermittent
    17963 - Charge Pressure: Maximum Limit Exceeded
    P1555 - 35-10 - - - Intermittent

    The battery was completely flat when I got back from holiday a couple of weeks ago, I charged it but it went flat again a couple of days later. I've since swapped it with the one from my boat which was also a Bosch Silver although the one from the boat was 55Ah and the one from the car was 60Ah. The problem I have has only happened since the battery was changed. Could this be related or is it more likely a dodgy O2 sensor and the battery code was just thrown up when the battery died? I got the codes cleared and will read them again tomorrow after I've had it out for a drive.
    #25
  27. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Oct 4, 2012]
    It's the "charge pressure" error that's responsible for soft limp. Could be a dodgy N75 or a split hose.
    #26
  28. blued
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    blued Member

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    [Oct 4, 2012]
    Thanks, so is the next step getting a boost leak test done? I've seen this boost leak tester kit on ebay. Should one of these do the job?
    #27
  29. Westy
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    Westy Double Dark Side! Diesel & 8P

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    [Oct 4, 2012]
    #28
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  30. blued
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    blued Member

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    [Oct 4, 2012]
    Thanks again, I'll need to check all the pipework at the weekend. I suspect it will just be the charge pressure code that comes back tomorrow but we will see!
    #29
  31. fluffsri
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    fluffsri Member

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    [Oct 5, 2012]
    Bluey, we never cured it. It was also on a std map and still is. Westy we has it scanned,.live scanned when driving.and it doesn't show a fault. It give an over boost signal but that's it. Tried2 New N75 valves ans even a manual but it didn't like that. Tried loads of the usual suspects and nothing changed it. It won't cut in.1st or 2nd andwill go to the recline but in 3,4, 5 and 6th it dies at around 54/5600 rpm. Were trading it in soon as had enough.
    #30
  32. jezzy
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    jezzy Member

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    [Oct 5, 2012]
    fluff
    did you look at your coilpack wiring harness.
    This becomes frayed over time and causes some of the issues you have.
    Try stripping it back to where it joins the loom and checking ( mine had about 10 holes in it)
    And its free apart from a roll of insulating tape.
    #31
  33. fluffsri
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    fluffsri Member

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    [Oct 5, 2012]
    No mate, first I've heard of this. I'm on my jollies at the mo so may take a look at it when I get back. To be honest Vik is so fed up with it she is prob trading it in with in the next 2 weeks.
    #32
  34. karl210
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    karl210 Member

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    [Oct 7, 2012]
    if your on the standard tip it could be collapsing, turbos suck really hard (giggedy) and these crappy standard tips go weak over time, give it a squeeze where it comes from the airbox and bends down the kindof ribbed bit but even still mine was collapsing and it still felt like it would hold up.
    #33
  35. blued
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    blued Member

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    [Nov 20, 2012]
    Just a quick update, I replaced a hose clip on the inlet pipe because it had definitely moved a bit since I had it off to do the v belt. It seemed ok for a while but I'm intermittently seeing the boost gauge suddenly fly up and it goes into soft limp. I've also had it go into soft limp mode from first start up of the day without giving it any high boost. Does this point to the N75 rather than a boost leak?
    #34
  36. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Nov 21, 2012]
    what codes did it pop up?
    #35
  37. blued
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    blued Member

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    [Nov 27, 2012]
    Sorry for the delay I didn't manage to get the code read until today. Just the following code now -

    17963 - Charge Pressure: Maximum Limit Exceeded
    P1555 - 35-10 - - - Intermittent
    #36
  38. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Nov 28, 2012]
    limp mode then from overboost..
    still doing it?

    potential causes a dodgy n75 valve and or pipe leaks or sticking wastegate/actuator
    #37
  39. blued
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    blued Member

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    [Nov 28, 2012]
    Yeah it does it from time to time. I've checked the hoses but there is nothing obvious, I realise that under pressure it could be a different story though. I also forgot to mention that sometimes when it gets above 10 PSI there can be a point where it jolts, if that makes sense? Almost like a misfire.

    I didn't think of the actuator - if I spray WD40 into where the actuator rod comes out and work the rod in/out could this help if the actuator was sticky?

    I bought a Golf TDI a few years ago that had been diagnosed with a faulty turbo but it turned out to be a bit of grit stuck in the actuator arm. I'll price an N75, does anyone know what the return policy tends to be at Audi for unwanted parts if it turned out to be something else?
    #38
  40. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    [Nov 28, 2012]
    when cool, see if you can pull the actuator arm out.. if it moves that confirms.. but the actuator capsule itself could be leaking.
    if you have access to someone with a smoke tester, you may be able to find a leak.. N75 valve could be the cause also.. You will have to ask the supplier re their returns policy.. They may not accept it back being electrical..
    #39
  41. blued
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    blued Member

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    [Dec 31, 2012]
    I can move the actuator arm no problem so will rule that out for now. I've ordered an N75 valve to try, will sell it on if necessary. Hopefully that will sort it, I'll keep you posted.
    #40

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