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  1. #1
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    Question '99 S3 - New Owner - Boost Issues / Power Loss

    Alright Fellas, I picked up my S3 last week and i am very happy with it so far. It has the QST 260Bhp upgrade package (have invoices for everything) I believe it may even be a replacement ECU, Miltek SS system and Forge Recirculation Valve, otherwise it's standard engine wise. I've been driving it a week or so without issue and the acceleration is unbelievable. However, driving home a few days ago I noticed the power wasn't coming in as low down in the rev range and it isn't as fast as it should be. It still goes but the real power is missing. It's almost like it isn't boosting properly. I've been reading a load of threads on here to get my head around things, and last night has a good look in the bay to see if anything was amiss.


    • Can't see any split pipes
    • Already disconnect MAF sensor and it doesn't make any difference (also took it out to look at it and it clean) It's a plastic square thing which I assumed would be more of a lambada sensor type device but there you go!
    • Removed Fuel Pressure Regulator and that was clean and showed no signs of damge/blockage etc

    I'm thinking it could either be the N75 valve, PRV valve or the PCV breather (I am still very new to these engines so abbreviations are confusing, if anyone is able to explain what these abbreviations are in full i'd be appreciative!) Thing is there is no way to visually inspect these. I am pals with an Audi technician and he scanned it using a Snap On Diagnostic reader at the weekend while I was getting a fresh oil change and we found no faults, however, at this point the car was still going strong without issue, and only had the problem this week. Will try and scan it again when I get a chance (he is always very busy), but I am wondering if any of you guys have any advice as to what the issue may be? I can hear the turbo sucking, possibly sounds a touch louder and hollow which leads to think it could be the PRV valve after reading the symptoms described in this thread:

    2001 S3 Boost Leak


    Also a pic of the Forge (not sure whether it's a dump/wastegate/ or re-circulation valve actually) and the bay etc. Excuse the poo pics they're off my iphone.

    Engine Bay with covers removed:




    Also check the FPR and that was clean and fine:



    Forge (TBC) valve:



    Here's where it was plumbed into. There was oil mist and crap here but it's old dirt not fresh so I cleaned the area after removal:




    Overall the car is pretty mint and the previous owner has spent a fortune maintaining it (he has owned it 11 years!) so I want to get it running correctly and look after it well. It's a great car but this issue is stressing me out!

    Any help or advice would be great. I love the car and want it to be running 100% as it goes like a rocket!

    Thanks

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  3. #2
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    Best bet is to get it scanned with VCDS, have a look in the vcds section to see if there is anyone near you who may help.

  4. #3
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    So I just need one of those cables and to download vcds lite to scan it?

    Also should mention the idle varies a touch too. Yesterday on start up after work was just ver 1000rpm but today sat just under?

  5. #4
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    Also should I be concerned about all the oil mist around the waste gate pipes?

  6. #5
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    Anyone?

  7. #6
    s3dave's Avatar
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    Just clean it up and keep your eyes on it..

  8. #7
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    In order to scan it using VCDS do I just need one of those cables then the lite version of the software? It's definitely not on full power and not sure if it's getting worse (it's probably the same)...

  9. #8
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    Yep. Order a cable of eBay (around £10) and software for ross tech. It's limited in functionality but can give you faults codes for the whole engine.

    You can also clear them. For the cost I recommend anyone if a vag car to get one.

  10. #9
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    Also and a long shot but check all hoses top and bottom for leaks, i was convinced my turbo was on its last legs over the weekend, down on power and smokey. had a good look over it in the night and found a huge whole in the underside of a boost pipe! :O changed in a low and behold shes now better then ever! worth a shot seeing as its free to have a look!

  11. #10
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    Ok thanks mate. I scanned it just now using the Snap On diagnostic tool and it only showed the fault where i had disconnected the MAF sensor, nothing else, so now I have to see if its a split pipe or one of those valves (N75/DV/or pcv etc.). Argh I'm sure it's something simple bit just trying to find it! Anyone in Hertfordshire who knows their stuff with S3's?

  12. #11
    Adam P's Avatar
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    I had this issue with mine and after scanning the car and searching the internet i had a combination of boost leaks from pipe work and needed a new air flow sensor. Low and behold she pulls like a train again
    2001 Audi S3 8L Ming Blue - Rebuild Complete


  13. #12
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    Quote Originally Posted by Adam P View Post
    I had this issue with mine and after scanning the car and searching the internet i had a combination of boost leaks from pipe work and needed a new air flow sensor. Low and behold she pulls like a train again
    Argh I need to sort mine again! How did you discover which pipes were affected? I had a good look under the inlet manifold last night took a few bits out but could see any cracked pipes at all. Really need to smoke test it or something as it has to be a leaky hose. Failing that one of those valves!

 

 

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