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S3 8p boosting issues

Smithy23 Oct 6, 2019

  1. Smithy23

    Smithy23 New Member

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    Hi guys bought a audi s3 8p and seams it's under powered. Running 225bhp and cant find the issue.

    So far what I have done to try and find issue is. Smoke tests to find boost leak. Found leak on diverter valve. So changed that out with new G model.
    Changed n75 valve
    Changed maf
    Changed pcv
    Car still does not run any better. Now is garage them looking for problem. Where they have check actuator to make sure its holding boost.
    Car is running forged hoses with a piper cross filter.
    ECU is asking for correct boost pressure but not getting correct pressure.
    Also done a compressor test and all good across all 4.

    So now at loose end with no fault codes showing. if anyone can help would be good.
    Thanks
     
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  3. Smithy23

    Smithy23 New Member

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    When checking spark plugs and coil packs. Spark plugs was pretty white.
     
  4. SootySport

    SootySport Well-Known Member Team Silver

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    That means the plugs are too hot due to bad timing or fuel mixture problem. I wouldn’t drive the car until it is fixed, else you’ll end up with holed pistons due to overheating.
     
  5. prt57

    prt57 Well-Known Member

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    I would have taken the car to RTeeh in Nuneaton. Their knowledge on these cars and this type of problem is amazing.
     
  6. Smithy23

    Smithy23 New Member

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    I would if it was closer 5hrs away. Was hoping it was actuator not holding boost but it is. Going to recheck n75 today as wasnt a genuine one put on.
    And maybe map sensor because there is a repair done to wires
     
  7. samuelh_888

    samuelh_888 Well-Known Member Audi S3 Black Edition Manual

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    Were all the other parts you replace genuine items?
     
  8. Smithy23

    Smithy23 New Member

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    No they was not. As only could get them local on day. When car was in for mapping
     
  9. samuelh_888

    samuelh_888 Well-Known Member Audi S3 Black Edition Manual

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    You didn’t proceed with mapping I assume?

    Get genuine parts on, if you still have the issue then have it smoke tested to see if there is any vacuum leaks.
     
  10. Smithy23

    Smithy23 New Member

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    No didn't map. Had smoke tester on it. And didn't find any leaks
     
  11. nluk100

    nluk100 Well-Known Member

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    Are you taking the car to a VAG specialist ? where are you located?
     
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  13. Smithy23

    Smithy23 New Member

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    I'm located in plymouth devon so pretty far away for alot of things. Going to call garage at some point today see how getting on. They know there way around an engine.
    Spoke to them couple of days ago and said by looks ecu asking for correct amount of boost pressure. But actuator not getting correct amount to open fully.

    That's what it sounds like.
     
  14. nluk100

    nluk100 Well-Known Member

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    What boost is it requesting (max)? Is it modified in any way? Repair to the map sensor wire is odd, it's usually the maf wiring that gets damaged as it's disconnected during servicing etc... Definitely need to look at this more closely as this does control max boost and you may be in limp mode. Do you have any fault codes (do they have vcds?)
     
  15. Smithy23

    Smithy23 New Member

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    The n75 repair was because the connector clip was broke so put new one on. With electrical connectors. They have vagcom and only code it showed was something to do with boost limit not exceeded. Something like that.
    Here is some pics he sent me.

    He also said that if he seen this it would be normally pointing to n75. But I just replaced it
     

    Attached Files:

  16. Smithy23

    Smithy23 New Member

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    I've not seen repair to map sensor garage seen it when looking into issue. Only mod on car is a open air filter.
    Had a dv + mod but replaced now with new dv.
     
  17. nluk100

    nluk100 Well-Known Member

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    Not easy to read those graphs but it looks like it's boosting a max of 0.6Bar (1.6Bar Atmospheric) - that would suggest limp mode to me. Smoke test is not a good way to check for boost leaks, it's fine for vacuum. They need to pump around 1Bar of air pressure in via the top of the turbo inlet. Boost leaks are fairly common around the intercooler and it's pipes. Get them to check for any oily residue around the inlet and outlet pipes on the intercooler. What year is your car, as the facelift models have plastic end caps and these can leak too.
     
  18. Smithy23

    Smithy23 New Member

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    It's a 2008 model
     
  19. nluk100

    nluk100 Well-Known Member

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    2008 was the year the facelift came out - the headlights are different on the earlier models
     
  20. Smithy23

    Smithy23 New Member

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    Thanks for the help, I have researched and researched and it could be so many different things to make this happen.
    I did have one code come up when i first had car in for remap which i think was P0299 Boost Pressure Regulation: Control Range Not Reached but since I changed some valve its now gone with no codes showing.

    when researching the things that came up with when looking into it was
    *Wastegate fault with the arm flapping abit.
    *Spark plugs and Coil packs
    *Map sensor
    *lots with Dv - Which Ive changed
    *Boost leaks
    *N75 - Which ive changed
    *MAF - Which Ive changed

    done compression test and they was fine over all 4 but plugs was white and only been in there 1k miles, cambelt and water pump was done at same time maybe timing out?
     
  21. Smithy23

    Smithy23 New Member

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    Got car back from garage for weekend and going to dig into the possible causes above, anything i should look at while got car back?
     
  22. K96

    K96 Member

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    My car was suffering from a similar issue but my car was misfiring before going into limp mode and I'm not sure if yours is doing the same.

    Does it misfire at all ? Or is it just constantly in limp mode

    Sent from my SM-G973F using Tapatalk
     
  23. Smithy23

    Smithy23 New Member

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    No misfire. Might have solved issue going to double check tomorrow
     
  24. Smithy23

    Smithy23 New Member

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    But need vagcom to double check
     

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