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Won't Boost - Freshly Turbo'd 325IS (MS)

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    Won't Boost - Freshly Turbo'd 325IS (MS)

    Hey Ya'll,

    Long time lurker. I have been building a Turbo M20 for the last few months - first E30. I'm new to MS and I have a MSPNP2.

    Issues: around 3500 rpm, under a light acceleration, right as I switch from vacuum to boost, the car hits kind of a rev limiter.

    I'm already nervous enough boosting for the first time in this 25+ year old car.

    Some background:

    - I have a boost solenoid, currently hooked up, but not activated (therefore, I assume that it will run the rated wastegate pressure per spring).

    - The manifold line goes to the boost solenoid, and then to the wastegate. The waste gate also receives a line from the manifold.

    - I do not see anywhere (in .msq) that may indicate why my car hits a "soft" fuel cut..ms

    I have attached the log file and .msq file. I'm a first time tuner and I'm making my way through it. Any tips/hints are welcomed, as well as constructive criticism.

    Find files here: https://drive.google.com/open?id=0Bz...GlJNjQ0d0ZRZDA

    If someone could tell me how to properly post files, that'd be awesome.

    Thanks.
    M
    Last edited by mbhill92; 05-28-2016, 11:59 AM.

    #2
    If there is any other information that ya'll need from me, just let me know. I'm still having this problem. Played around with some of the settings and still cannot seem to get it to rev past 3500rpms.

    Comment


      #3
      I remember hitting a brick wall around 3500-4000 and not being able to go into boost.
      My crank position sensor was loose and a bit away from the gear - was gravy after that.

      I don't think the waste gate is playing a role here. If it's not opening, you should be able to boost to infinity and if it's stuck open, you should still be able to rev through RPM range regardless - you'll just get no positive pressure.

      Try brakeboosting to see if the car is even able to build pressure to rule that out - maybe your turbo is just on the larger side.

      1991 325iS turbo

      Comment


        #4
        Originally posted by ak- View Post
        I remember hitting a brick wall around 3500-4000 and not being able to go into boost.
        My crank position sensor was loose and a bit away from the gear - was gravy after that.

        I don't think the waste gate is playing a role here. If it's not opening, you should be able to boost to infinity and if it's stuck open, you should still be able to rev through RPM range regardless - you'll just get no positive pressure.

        Try brakeboosting to see if the car is even able to build pressure to rule that out - maybe your turbo is just on the larger side.
        That is what I have been reading. I keep getting a #2 log count error. So, I cleaned it and still having an issue. Maybe, I will fiddle with it a bit and/or replace. Thanks!

        Comment


          #5
          I was gonna get into the whole "10k resistor inline with the VR sensor" thing but you said you got the Plug n Play unit.

          1) Where's your throttle position sensor? MAP based accel enrichment is sub-par, I would not recommend using it.

          2) I would also turn off "EGO corr" (O2 sensor feedback) until you have a more developed tune. You don't want extra algorithms adjusting your fueling behind the scenes, especially with boost. It can cause problems by itself, and make general troubleshooting/issue isolation much more involved.

          3) I guarantee you can feel those lean spots, as indicated by the red arrows. TPS-based accel enrichment will fix this once you set it up.

          4) I would also turn off boost control until you know you can hit boost. EDIT: Definitely turn this off for now. Your boost control is enabled, but your boost duty table is zero'd out across the board.

          The problem doesn't seem to be stemming from boost. In other words I think you'd be having the same problem even if your setup was still naturally aspirated. If you know you're getting a tooth/log error, I would investigate the crank position sensor. Make sure it's OEM, not damaged, properly mounted, and has the correct electrical resistance (google it real quick but I'm pretty sure it 540 ohms +/-10). If you know it's super old or have never replaced it before, I would grab another one. Like I mentioned first, it is possible to screw up the CPS circuit if you built the board yourself. I wired mine up backwards initially because I found conflicting info on the web. The car would crank, but not run and the tooth log file looked weird. I switched the polarity of the sensor and all my problems went away.
          Attached Files
          Last edited by EatsHondas; 06-04-2016, 08:43 AM.
          1989 325i Lachssilber Sedan
          5-Speed Swapped
          M30B35 Swapped
          MegaSquirt MS3X

          1987 325i Lachssilber Sedan
          260k OEM Automatic Daily Baby

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