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Thread: Overboost shutdown at 0 psi

  1. #1
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    Overboost shutdown at 0 psi

    What would cause this, i am working on this car for someone else, i know there are a handful of wiring that is not done the best way but overall it is running fine the first time it ran fine and got to 10 psi, the second test drive every time it got just past 0 psi on the gauge it would hit overboost cutout.

    What would cause this, i have the purge and wastegate solenoid codes but looking into the 87 LM code that shouldn't cause this problem.

  2. #2
    Supporting Member Turbo Mopar Contributor zin's Avatar
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    Re: Overboost shutdown at 0 psi

    If you can get a scan tool hooked-up, do it! Then look at what it shows for manifold pressure, you might be having a repeat of the problem I had with my Omni when I first got it, which is to say a bad MAP sensor, telling the ECU that you're hitting 15+PSI when you're nowhere near that!

    I actually had it cut out while still in vacuum.

    The quick and dirty fix would be to try a KNOWN good unit from a different car, try that to see if it fixes the situation.

    Mike
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  3. #3
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    Re: Overboost shutdown at 0 psi

    You're certain it's hitting overboost? It's setting a code for it?

    If so, wrong map sensor? like maybe a tbi one?

  4. #4
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    Re: Overboost shutdown at 0 psi

    Good ideas I know it is the correct Map I will try to log a run to see what the computer is seeing. Maybe the MAP is bad, Thanks

    Sent from my SM-G900T using Tapatalk

  5. #5

    Re: Overboost shutdown at 0 psi

    I would check all vacuum lines and do a wiggle test on all the electronic connectors as well

  6. #6
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    Re: Overboost shutdown at 0 psi

    Check for vacuum leak to the map sensor.

  7. #7
    Visit www.boostbutton.com... Turbo Mopar Contributor ShelGame's Avatar
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    Re: Overboost shutdown at 0 psi

    There's no OB set at 0psi. So, it's technically not overboost. But, if you have certain codes (TPS or MAP especially), the rev limiter can be set very low. The rev limiter and OB use the same shutdown code. So that it may seem like you are hitting OB, but it's actually a limp-mode rev limiter at like 3k rpm.

    Check for MAP or TPS codes.
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  8. #8
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    Re: Overboost shutdown at 0 psi

    Quote Originally Posted by ShelGame View Post
    There's no OB set at 0psi. So, it's technically not overboost. But, if you have certain codes (TPS or MAP especially), the rev limiter can be set very low. The rev limiter and OB use the same shutdown code. So that it may seem like you are hitting OB, but it's actually a limp-mode rev limiter at like 3k rpm.

    Check for MAP or TPS codes.
    Great information thanks, I know it had a TPS code in the past, this could be it.

    This is actually in a sand rail like some may seen in another thread and the ecu is wired wrong so it clears codes everything you shut it off, I am going to rewire it correctly and go from there.

    Sent from my SM-G900T using Tapatalk

  9. #9
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    Re: Overboost shutdown at 0 psi

    Ok hopefully some of you can answer this in this thread instead of a new one, the wiring for the ASD is messed up, I have read that the relay for the ASD is inside of the power module, Does this mean that the ASD output directly powers the coil, injectors, and Fuel pump with no other fuses or relays?

  10. #10
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Overboost shutdown at 0 psi

    That's correct. Once the ASD is triggered it's straight to everything on the Z1 circuit with nothing to stop it.

  11. #11
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    Re: Overboost shutdown at 0 psi

    Quote Originally Posted by cordes View Post
    That's correct. Once the ASD is triggered it's straight to everything on the Z1 circuit with nothing to stop it.
    Great thanks for the info

  12. #12
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    Re: Overboost shutdown at 0 psi

    my old van was doing that when i bought it. found out they had a non turbo map sensor wired in....

  13. #13
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    Re: Overboost shutdown at 0 psi

    first test drive after fixing a bunch of wiring, still doesn't make sense ran good but popped pipe off when i let off with no bov any idea what can cause this

  14. #14
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    Re: Overboost shutdown at 0 psi

    also really weird when i use a otc 4000 or MPScan the RPMs drop when it starts logging or communicating, also as i will upload in a log the cylinders are indicating weird retard on mp scan, i don't think i was seeing that on the scan tool,

    Another thought could EMF be messing stuff up, the bulk of the wiring is right next to the coil, i know i couldn't get reading on other logging stuff anywhere near the coil

  15. #15
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    Re: Overboost shutdown at 0 psi

    log file i tried to clip it to the driving time
    https://drive.google.com/file/d/0B6S...ew?usp=sharing

  16. #16
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    Re: Overboost shutdown at 0 psi

    Now I am getting these codes as soon as I turn on the key, I am getting sick of this thing, I tried different LMs same thing, must be something else in the wiring

  17. #17
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    Re: Overboost shutdown at 0 psi

    Adding weirdness to the list MPScan gives the codes above but the otc 4000 only gives 12, 31, 36

  18. #18
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    Re: Overboost shutdown at 0 psi

    found out that the MPScan is the problem with weird codes, made a few good passes and found that the TPS code like Rob suggested is causing the 3k RPM limiter and what i thought was overboost, i hope that changing that in addition to all the crappy wiring i already fixed will finish the job

  19. #19
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    Re: Overboost shutdown at 0 psi

    Just to wrap up the thread, new TPS fixed the problem, and got it running good.

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