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  • Boost control spike solutions?

    Having a huge problem with a car i can`t seem to stop from having huge boost spikes during transitions.
    From what i can see from logs, the top port of the wastegate can`t unload fast enough to start controlling boost. ( a test with just a static PWM signal works as it should. )
    My theory is that the top chamber is filled with air pressure during spool up, but by the time the ecu starts pulling boost control DC to the time full boost is achieved the valve isnt able to flow the amount of air needed to empty the top chamber sufficient for the wastegate to open.

    Even with boost range set to 250 ( max) and dynamic comp at anything from 1 to 50 wont stop it from overshooting in high gears. ( target is 330kpa, and turbo is able to build 400+kpa)

    So looking for ideas for solutions here.
    ( large turbo, 4 cyl, e85, mac valve, 44mm tial with 200kpa spring ( will open at 200kpa but climbs to 250@redline) ) a 20% static PWM signal will result in about 270 at spoolup and 260 at redline)

    WG have a straight hose to bottom port, and mac valve to top port. ( separate supplies ) ( about 20cm hardline total length of hose between supply and wastegate. )

    Only ideas i can think of is:
    1: just have the top port valve at 20% static and add another one to the bottom port and have the ecu control that one with clc
    2: use a restrictor at the supply for the top port valve to limit the amount of air it can supply the top chamber.
    3: get a larges valve that is able to unload the top chamber faster ( the normal small mac valves does not have much flow capabilities )

    ( i have logs of this if needed)

  • #2
    Logs and cal file to autronicsm4@yahoo.com.au and customers@autronic.com.au please.
    He gets his lap dogs to do his talking for him. Buzzard is a good example.

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    • #3
      I have read your email. Ian has always advised not to take the boost control valve supply from the compressor cover, I believe his concern is that the air temp will exceed the allowable temp for the valve.

      Can you unplug the electrical connection to the MAC valve , do a run and send the log file pls.
      He gets his lap dogs to do his talking for him. Buzzard is a good example.

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      • #4
        Hi.
        I just sent a log file where the boost controller was disconnected.
        Also the idea that air temp is the problem could be some of the reason for this. ( this was working great before when i had a older version of the billet turbo i have now. but back then i was using a boost source that was after the intercooler. and at some point i changed to a newer version turbo. and thats when the problems started.
        So if it`s something that changed with the turbo or if it actually is heat that does this i`m not sure. ( and cant test before the snow is gone. )

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        • #5
          I would expect the boost to stay flat with RPM, and when I see it rising with RPM I start looking for flow problems with the wastegate. If you apply air pressure to the bottom port of the wastegate diapragm, say 30 psi, and remove it quickly, do you hear the wastegate close with a satisfying clunk?
          He gets his lap dogs to do his talking for him. Buzzard is a good example.

          Comment


          • #6
            I have tested the WG, and it works as it should. even disassembled it and checked that everything is ok. ( this is a new genuine PTE 44mm witch i bought at the same time i changed to the newer gen turbo. )
            The flow is at the limit on low boost, so the creep it from a flow issue. but that should only be a issue during low boost.
            And the problem is gone when using a open loop type of boost control. ( as long as i run more then the 250kpa@8000rpm that you see it creeps up to with valve disconnected.)

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            • #7
              Did you have any other thoughts on this Chris?

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              • #8
                Many, including the thought that steady state is not transient state.
                He gets his lap dogs to do his talking for him. Buzzard is a good example.

                Comment


                • #9
                  Originally posted by Chris View Post
                  Many, including the thought that steady state is not transient state.

                  And by that you mean?

                  Since its winter here, more testing will have to wait until spring. but next thing im going to test is using a supply from the cold side. and also try to use a restrictor on the air supply to the valve.

                  Do you have any other way you would go about it?

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