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Help with a boost issue. Audi S2 Coupe with RS2 upgrades

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  • Help with a boost issue. Audi S2 Coupe with RS2 upgrades

    In the picture is the fault I have.

    Basically the car cuts boost hard at about 1 bar then the boost comes back and then it cuts again and so on. The car accelerates smooth up to about the 1 bar point then the cutting boost starts.

    Twice during the test drive the boost was normal 1.8/1.9 bar then the boost issue appeared.

    I disconnected the MAF and put my pressure plug in, closed off the rocker breather pipe to do a boost leak test. The car has no leaks from what I can see.

    I am thinking this could indicates a sticking N75.

    Any pointers will help.



    Attached Files

  • #2
    Just tested the outputs from the ECU all working. All going on and off. N75 operated ok.

    Comment


    • #3
      WG spring too stiff ?

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      • #4
        I don't think so its the original WG and spring. It has never been opened. Several weeks ago the car was running ok.

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        • #5
          Clean the maf connector

          S2 Coupe 3B Project


          Ur quattro restoration

          S2 Avant

          Boost is the new rock and roll!
          sigpic

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          • #6
            MAF connection cleaned, no change.

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            • #7
              If it’s cutting at 1Bar it’s not really exceeding max boost pressure.
              The fault code may be misleading.
              This is almost always to do with the MAF.
              Did you clean the pins by the method described in the MAF connector thread?


              S2 Coupe 3B Project


              Ur quattro restoration

              S2 Avant

              Boost is the new rock and roll!
              sigpic

              Comment


              • #8
                In my case changing the Maf connectors wasn´t enough, things got better but problem only completly solved when i changed the connectors and more than a foot of wire that came with each connector bought from the dealer!

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                • #9
                  Will strip the connection out the MAF connection today and give them another good clean. I have a set of new connections from Audi (if I can find them) so I may try to replace all of them.

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                  • #10
                    Found the MAF connectors.
                    Attached Files
                    Last edited by orsum; 10th September 2019, 06:57.

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                    • #11
                      First thing this morning I cleaned the MAF connection. Took the car out for a drive and it had no boost cutting issues

                      So the job for today is replace the connections with new OEM gold plated connectors.

                      Even though I had cleaned them recently it obviously does not mean they are clean

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                      • #12
                        After take out the pins from the connector and using 2000 paper to clean them and doing the same to the MAF connections I was not convinced it was the connector that was at fault, all the connections had lots of spring loaded tension which will help with making a good electrical connection. The connections on the MAF itself did not look super clean so I spent lots of time cleaning both sides of the blades.

                        In saying that I am certain a dirty connection was my problem. Was it the blade or was it the connector or a combination of both. How do you stop these connections getting dirty / corroded again? Do you guys use an electrical connection grease.

                        I decided to give both a good clean and to see how long it will take before the issue returns. I hope its a long time.

                        My set of new MAF connector pins are now locked away waiting to be used another day. Time will tell.

                        Took a test drive today to see how the clean worked. The performance was very good and very smooth.

                        Thanks for the support and recommendations.

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                        • #13
                          I believe there’s a hard layer of corrosion that builds up in between the mating surfaces of the female pin. Once I’d taken the pins out and cleaned between the prong with 1000 wet and dry I’ve had no further problems in years. Like you I gave a set of new pins in reserve.
                          I’ve got a small tube of silicon dielectric grease that I use on connectors to keep out moisture. Just a smear.

                          S2 Coupe 3B Project


                          Ur quattro restoration

                          S2 Avant

                          Boost is the new rock and roll!
                          sigpic

                          Comment


                          • #14

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