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Good news and bad news!! PC good, remap bad!

Discussion in 'A3/S3 Forum (8L Chassis)' started by simch, Mar 18, 2007.

  1. simch
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    simch Active Member

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    [Mar 18, 2007]
    Well its been an interesting weekend with good news and bad news.

    First the good, finally cracked open the Porter Cable and all the gear I have bought to go with, (thanks to ebay Stevie and Polished Bliss for all the gubbins).
    well still a bit new to the PC, but having successfully mopped cars with a rotary before, I am not shy to it, and managed to remove the annoying 2 inch long "scratch" in the bonnet, the annoying rear bumper scratches courtesy of previous owners missus scraping the shopping in and out of the boot!) and one on the roof that was about 7 inches long.
    So it looks super dooper mint now, very few swirl marks if any, and resplendant in its Zymol titanium too!

    So overall pleased with that and the spacers arrived for my audi tt BBS spkit rims yesterday, just awaiting bolts now and it should be looking nice..!

    Now the bad news, went to try an interim remap yesterday a generic one from a custom mapper, Jabbasport, just an interim stage while the BT bits and bobs are acquired....! Mine is a late 2003, S3, BAM, and an import if that makes any difference...?
    Seems to be healthy enough, but never felt as quick as my AGU mk4 with K 03sport turbo, proabbly as quick top end, but the short gearbox on the s3 I think was flattering a motor that was a bit asthmatic. So a vagcom check revealed no probs, car has 46k on it. New prepared map was loaded in, vagcom check again then a vagcom log run was done while I went out for a blast about......
    Immediately, the part throttle torque increase was impressive, the car surging forward at half throttle with gusto...but then if you nail it in 2nd from about 2k revs, there is a massive thrust of boost, a loud whilstle as it does so, then it gets to about 4k and there was a strange noise form the turbo, like a sort of screeching or farting noise...and the boost seemed to drop off very quick...above 4500, it felrt near identical to before, maybe a bit quicker, but not at all progressive power as my k03 sport is....?

    So back to base for a check of the logs.......seemed to be getting the advance pulled back possibly due to lower octane fuel, although it was on super unleaded..? So the map was tweaked down a level, the original would have suited Vpower gas I think, we dont get that round here! So same process off I went again, felt softer, a bit more progressive, but after a mile or so of driving, again, got this same sensation of weird noise and the car being pulled off boost....? Weird. Read all the logs again, seemed far far better, but I was not happy, not having driven a remapped s3 in some time, it just did not feel right...!
    So on went the boost guage, and the experts took it out for a run....came back, (this was on the softer map with max 1.6bar dialled in).....OMG.. it had been running up to 1.6bar no prob, then under load, the boost was creeping up to over 1.8bar.....?/ Possible N75 valve problem..., so a new one was fitted, and the same map tried again......better infact, but the same symptom, albeit it toook longer to creep up and up...? Strage noise appears to be the compresser wheel complaining!!
    So (fair plays to the guys!!) they load in a new mapo, this time an off the shelf map for the 240bhp TT sport, with the torque tweaked to give a bit more pull mid range, but max I think was 1.4bar........roat test showed it again pulling up to 1.7bar and not at all happy.......?
    So after about 5 hours of tweaking, the original map was reloaded......road test showed boost climbing to 1.2bar steadily, max should be 0.9bar I think...?

    So overall, its a buit perplexing. The MAF was a little "low" on vagcome reading, (8.5grams at 3k revs) a new one would have maybe shown 9.3 or so although up to 10grams has apparently been seen). But it was not felt that this was the cause.... By this time fuel was out and local gas station only had 95 ron, so this was not helping, and despite the "increased" boost, the car still does not feel a quick as it should IMO, (and the guys at Jabba).

    So I am a bit at a loss, their feeling is it could be a turbo problem, but it is a stock car, a late one too and I think has had a very easy life so far! Possible sticking wastegate actuator, but very difficult to confrim or fix really, not when its hot anyway. Jabba guys seem happy enought o book it in for BT, as they will be able to map around anything with the new turbo, and whilst I'll have a new MAF and N75 at that time, (plus cambelt, waterpump and any other sensors etc) I am just a bit concerned that if their is anythign "duff" that is not showing on Vagcom, and it subsequently fails, it could cause a problem with the new set up...?

    But surely boost is only controlled by the ECU, dumpvalve, N75 and the wastegate....so as these will all be either renewed or remapped with new set up, it should all be OK....?


    I would still like to understand what was going on yesterday, but as the jabba guys say, the motor is very sound itself, and pretty much everythign else will be renewed with the conversion...? I questioned the DP and Cats, and it appears knacked cats may cause these symptoms too, with the turbo chasing more boost if there is a blockage of sorts....? Again a new DP adn cat will be fitted.. but I would still like to understand whats going on!

    Any ideas or similar experiences...?

    PS bit thanks to the Jabba boys and girls who spent all afternoon with me and the puzzling problem, then refused to let me pay anything for all their messing as it ended up back as standard!
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  3. Tallpaul
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    Tallpaul Member

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    [Mar 18, 2007]
    Outstanding that Jabba didn't charge :)

    I'll have 50p on it being a leak at the join of the downpipe and turbo.
    #2
  4. simch
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    simch Active Member

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    [Mar 18, 2007]
    Would this give an overboost then...? I certainly cannot hear any leak, but it depends how big it needs be?
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  5. Gti Jazz Blue
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    Gti Jazz Blue Active Member VCDS Map User

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    [Mar 18, 2007]
    Another possibilty is a secondary hose, I had a problem with my Golf IV where the secondary hose to the N75 had come adrift and that caused boost issues with the boost realy strong and on or off. The hose stopped the N75 controlling the wastegate correctly.

    Paul
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  6. simch
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    simch Active Member

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    [Mar 18, 2007]
    replaced n75, hoses at that end seemd ok, but I will check them over.

    Also clean the EGR, and check the hoses to that too.

    Had us a bit stumped, but I am beginning to think its the wastegate sticking.
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