turbo cuts to zero boost

Discussion in 'Trucks [ Eighteen Wheelers ]' started by skman, Aug 23, 2016.

  1. skman

    skman Light Load Member

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    Aug 26, 2013
    Saskatchewan
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    I was on here a few weeks ago because I was driving down the highway and my boost pressure gauge (and datastar) was stuck at 42 psi. Everything was running good. Built boost when I needed it but the needle stayed pinned at 42.
    After shutting the truck down...it went to zero and worked fine for awhile. Then about an hour later...it was pinned again. Everything running great still and reset to zero again when I shut it down.
    It never did that ever again. Instead what is happening now is I'll be driving down the road and suddenly start dropping road speed with no power at the pedal and the turbo is at zero. Then it'll kick in for a second and cut out again showing the boost increase....then drop to zero again. It'll do that for a few miles sometimes....then it will start working again.
    I took it to a shop and they plugged it into the computer. It said there was a voltage loss. So they looked around and found a couple wires (on battery and starter) that weren't quite tight and wrenched them up. They said because it was working right now....that's all they could do and they were hoping that was the problem.
    Well it was fine today until I got loaded. About 100 miles down the road....it did it again. Then stopped. Then again about 60 miles later and then again a couple hundred miles later.
    I can't see anything strange on the gauges when it happens. Voltage is good...air is good...etc. just the turbo bottomed out at zero. With the turbo trying to kick in...then zero again until suddenly it starts working again.
    This is on a 14L Detroit. EGR out awhile back. Turbo was replaced at that time...now about 100,000 miles on it.
    Any ideas?
     
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  3. skman

    skman Light Load Member

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    Aug 26, 2013
    Saskatchewan
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    I should add...when it's working...it runs nice and sounds the same as always. And when it's not working....there's no noticeable new sounds either.
     
  4. pigeon river trucking

    pigeon river trucking Light Load Member

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    Jan 1, 2016
    michigan
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    Sounds like it could be the boost sensor. Had same issue on a 3406e changed sensor and it was fine after that
     
    Dave_in_AZ Thanks this.
  5. Sho Nuff

    Sho Nuff Road Train Member

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    I'm no mechanic, but maybe it has something to do with your fuel system. Just a guess.

    No fuel equals no boost.
     
  6. skman

    skman Light Load Member

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    Aug 26, 2013
    Saskatchewan
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    That's kinda what I was leaning towards too. When it was pinned at 42 on the dash and then reset with the key....I figured sensor or possibly a short in the harness. But i figures I'd ask here before I start throwing money at it.
     
  7. skman

    skman Light Load Member

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    Aug 26, 2013
    Saskatchewan
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    That's true. My Davco is still in good shape with fuel in the bowl. But i haven't checked it when this is happening. I did pull over one time...and I was able to take off and go through the lower gears but once I got into the top end of the transmission....there wasn't enough power without the turbo kicking in.
     
  8. little cat 500

    little cat 500 Road Train Member

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    Abbottstown PA
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  9. Dave_in_AZ

    Dave_in_AZ Road Train Member

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    Definitely sounds like a sensor issue. If shop cannot find with their diagnostic equipment however, could possibly be ecm going south.
    Few things are more frustrating than mystery electrical / sensor problems, just because of what you said, it really needs to have the problem when your at the shop. Some shops have the scope that that can test all the different sensor outputs, been down this road with a bad crank sensor, but it would run rough, when it acted up. I can't remember if it had to have the problem when they diagnosted it or not, I don't think it did.
    Good luck man, it is really frustrating.
     
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