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b5 s4, in and out of boost!

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  • b5 s4, in and out of boost!

    Well ever since i went stg+ i knew my car was a ticking time bomb, unfortunately that bomb went off a little less than 2 months ago. Turbo's are screaming, sounding more like a supercharger than a turbocharger, i take it that would be the dentist drill sound. Now what exactly is making that whinning sound? the bearings?

    Anyways onto the big question, Why would the car be consisitantly in and out of boost. I will get in and drive with the car building no boost, almost like the turbos are holding the car back from excellerating. As soon as i lift my foot of the throttle and apply it again i will have boost. And it will do this off and on all the time. Sometime it work normally, while other times i have to let of the throttle and than apply it again to have the turbo's build boost.

    What causes this? i figured if they were going to blow it will happen all at once, not piss me off to no end like this. Car is not smoking or using any oil either.

    Which is why i am stumped.

    Any feedback or info on this topic would be great.

    Thanks in advance

    Kevin
    Kevin

    2000 s4, Custom vast stg2+, piggie pipes, ssac catback, evoms intake, 710n's, eibach sportline springs, RS4 Reps, VDO boost guage

  • #2
    Re: b5 s4, in and out of boost!

    Soft limp mode. Scan the ECU for fault codes and see if you have positive or negative boost pressure deviation codes.
    Jordan
    Jerbel Autowerks

    Distributor of parts from:
    JAW, 034 Motorsport, Power Up Lubricants and OEM replacement parts
    (403) 690-7135
    jordan@jerbelautowerks.com

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    • #3
      Re: b5 s4, in and out of boost!

      thanks Jordan, its quite odd, i can get past my turbos being pooched cuz it still hauls ass, but when i have no boost at all it drives me nutz!

      i will be scanning for codes either tonight or tomorrow and doing a pressure test to fix these problems.
      Last edited by fazda; 05-12-2011, 03:13 PM.
      Kevin

      2000 s4, Custom vast stg2+, piggie pipes, ssac catback, evoms intake, 710n's, eibach sportline springs, RS4 Reps, VDO boost guage

      Comment


      • #4
        Re: b5 s4, in and out of boost!

        Check the hose leading in to your N75 valve as when there is a hole in it wastegate control gets all messed up and you get some boost sometimes then nothing other times. Also good to check the N75 itself as they have been known to go bad.
        2020 Toyota Corolla Hatch (At least its a Manual!)
        2001 Audi S4 (Trunk still smells like Ryan?)
        2001 Audi A4 - RIP
        2004 Mygale SJ04 - Racecar
        2013 Toyota Sienna - Baby Transporter
        2001.5 Audi S4 -SOLD
        1986 Reynard SF86 -SOLD
        2003 Jetta GLI - Garbage bin

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        • #5
          Re: b5 s4, in and out of boost!

          Don't listen to Roger, he has a hate on for N75's, Fed Ex, Customs and several other things.
          I may appear to be nice, but don't be fooled, I probably don't like you

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          • #6
            Re: b5 s4, in and out of boost!

            Thought he also had a hate on for his B5 S4
            --
            Rod
            Ex-presidente

            Drive

            2016 VW Golf .:R

            Drove
            2001.5 Audi S4 / Santorin Blue STAGE II+ / JFonz Tuned

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            • #7
              Re: b5 s4, in and out of boost!

              lol so should if check it or not.. haha
              Kevin

              2000 s4, Custom vast stg2+, piggie pipes, ssac catback, evoms intake, 710n's, eibach sportline springs, RS4 Reps, VDO boost guage

              Comment


              • #8
                Re: b5 s4, in and out of boost!

                Checking n75 lines and wastegate actuation should be done while testing for boost leaks. So yes
                I may appear to be nice, but don't be fooled, I probably don't like you

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                • #9
                  Re: b5 s4, in and out of boost!

                  ^ Agreed, although the N75 WG lines need to be tested separately from the rest of the boost-leak test.

                  A bad N75 is a possibility. It's not likely the WG lines. When you have a hole in a WG line, the car will tend to overboost
                  Jordan
                  Jerbel Autowerks

                  Distributor of parts from:
                  JAW, 034 Motorsport, Power Up Lubricants and OEM replacement parts
                  (403) 690-7135
                  jordan@jerbelautowerks.com

                  Comment

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