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Boost Pressure Builds Slowly 900 1993

posted by  tvpierce on  Tue May 27 03:38 CST 2003
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last visit: Tue Apr 8 06:40 CST 2014
[RELATED]

I just bought a 2nd '93 945T. The "new" one doesn't come up to full boost as quickly as the "old" one. On the old car, when I stomp on the throttle, the boost guage jumps immediately to full boost. On the new car, it gradually builds pressure much more slowly -- it takes about 3-4 seconds to reach full boost.
My first thought was that it was a leak in a turbo/intake hose. So I removed/inspected/cleaned all the turbo/intake hoses -- everything was in excellent shape.

My next thought is that the wastegate or actuator isn't functioning properly. Am I on the right track? Or should I be looking at something else?

Any suggestions are appreciated.

Jeff Pierce
--
'92 Mercedes 190E (my daily driver), '93 945 Turbo (a kickass family car), '53 Willys-Overland Pickup (my snow-plow truck/conversation piece)








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    * * UPDATE * * 900 1993

    posted by  tvpierce on  Thu May 29 03:42 CST 2003
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    last visit: Tue Apr 8 06:40 CST 2014
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    First of all, thanks to everyone for your feedback. I fixed the problem, so I just thought I'd post back with what I found.

    While poking around the wastegate, I found that the rod was disconnected. When I reconnected the rod, the boost began to work properly. Unfortunately, there's still some question about what corrected it -- here's why:

    1) I'm not sure if I knocked the rod loose or if it was already loose. Obviously, if it was already disconnected, then that's what fixed the problem.

    2) But if I knocked it loose, then I'm thinking that the actuator was bound up, and when I pulled on the rod to reconnect it, it freed up the actuator, and THAT'S what fixed the boost.

    I'm interested in anyone's comments on this conundrum.

    Jeff Pierce
    --
    '92 Mercedes 190E (my daily driver), '93 945 Turbo (a kickass family car), '53 Willys-Overland Pickup (my snow-plow truck/conversation piece)








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      congrats on problem solved... 900 1993

      posted by  Brian S on  Thu May 29 04:51 CST 2003
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      Ah, you lucky duck! Just go for a spirited drive & enjoy the boost!

      If you really want to worry more about this now... did you fiddle around with the wastegate arm and actuator rod before you hooked 'em back up? Did the wastegate move freely & easily? Did the actuator rod offer smooth resistance when you tugged on it? Perhaps the spring in the actuator got hung up in a compressed position... but it seems much more likely that the rod was detached and that was the problem.

      Did you put in a new pin to hold the arm on the rod?

      I had all this apart last weekend to change my turbo oil return o-ring (finally!)... so the memories are fresh...



      - Brian







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        congrats on problem solved... 900 1993

        posted by  tvpierce on  Sun Jun 1 13:21 CST 2003
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        last visit: Tue Apr 8 06:40 CST 2014
        [RELATED]

        It must have been just the rod, because now it flies. Even better than my other 945T.

        Jeff Pierce
        --
        '92 Mercedes 190E (my daily driver), '93 945 Turbo (a kickass family car), '53 Willys-Overland Pickup (my snow-plow truck/conversation piece)








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    Boost Pressure Builds Slowly 900 1993

    posted by  Brian S on  Wed May 28 05:20 CST 2003
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    The Mitsu turbos are said to spool up more quickly than the Garretts, but I don't think any turbo is supposed to spool as slowly as what you're experiencing.

    I believe you're on the right track suspecting wastegate rod/actuator... another item you could check is the compressor bypass valve. I've read here that a failed CBV will cause the engine to stumble when you let off the throttle under boost... though it seems like if the CBV diaphram had a leak in it, boost would build more slowly than it should.

    - Brian








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    Boost Pressure Builds Slowly 900 1993

    posted by  sped on  Tue May 27 16:38 CST 2003
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    According to my part numbers there is a faster spooling turbo made by mitsubishi. Both types were used depending on where the car was manufactured.








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      Boost Pressure Builds Slowly 900 1993

      posted by  tvpierce on  Wed May 28 03:43 CST 2003
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      last visit: Tue Apr 8 06:40 CST 2014
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      Sped,

      Were both Mitsubishi & Garrett turbos used during the '93 model year? (I assume Garrett is the "other" brand?)

      Jeff Pierce
      --
      '92 Mercedes 190E (my daily driver), '93 945 Turbo (a kickass family car), '53 Willys-Overland Pickup (my snow-plow truck/conversation piece)








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    Boost Pressure Builds Slowly 900 1993

    posted by  the kick inside on  Tue May 27 06:18 CST 2003
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    last visit: Thu May 17 09:58 CST 2007
    [RELATED]

    could be a newer turbo...i hear tell they boost less quickly...although mine is eager enough....how slowley is slowely?







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      Boost Pressure Builds Slowly 900 1993

      posted by  tvpierce on  Tue May 27 10:24 CST 2003
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      last visit: Tue Apr 8 06:40 CST 2014
      [RELATED]

      When I stomp on the gas, it takes 3-4 seconds to reach full boost.

      Jeff Pierce
      --
      '92 Mercedes 190E (my daily driver), '93 945 Turbo (a kickass family car), '53 Willys-Overland Pickup (my snow-plow truck/conversation piece)








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        Boost Pressure Builds Slowly 900 1993

        posted by  the kick inside on  Tue May 27 10:49 CST 2003
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        last visit: Thu May 17 09:58 CST 2007
        [RELATED]

        i would need to check, but depending on revs etc...i think mine might just about take that long as well since i put the new turbo on....

        certainly it isnt instant.....thinking about it that sounds a bit longer than mine...but not attrociously so...depends on road speed/gear etc...say 45 in 5th I would say thats slow....should swing up pretty fast...couple of secs say...

        just what mine does and we all know mine is NOT right generaly...








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          Boost Pressure Builds Slowly 900 1993

          posted by  tvpierce on  Tue May 27 14:21 CST 2003
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          last visit: Tue Apr 8 06:40 CST 2014
          [RELATED]

          The thing is, I have an identical 945T in my driveway that comes up to pressure almost instantly. Maybe I should swap the turbos for a little more scientific experiment. If the other turbo works better, maybe I'll just keep that one on the new car.

          Jeff Pierce
          --
          '92 Mercedes 190E (my daily driver), '93 945 Turbo (a kickass family car), '53 Willys-Overland Pickup (my snow-plow truck/conversation piece)







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