Help! Cummins ISX no Boost!

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Trouble65, Mar 9, 2010.

  1. Trouble65

    Trouble65 Medium Load Member

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    I have a 2004 Volvo with a 435 ISX. The problem that I'm having is this;
    Driving along with or without a load I step on the pedal and get 35psi boost and without warning boost drops down to 0psi. No check engine light or anything. No black smoke out of the stacks.
    I could lose boost for 5 sec or 5 min. Then all of a sudden full boost. Then I could drive the truck for an entire day without any issues and then it starts all over again. Friday I was driving and boost was all over the place. Under heavy pedal I got 35psi then within a second dropped down to 0Psi and instantly back to 35psi.

    Drove the truck to Kenworth Cummimns dealer. They put the truck on the computer, got billed $129 and were told there is nothing wrong with the unit. However if the problem persists to bring it back.
    Having said that they recommended that I take the turbo off and look at the blades to make sure it's free spinning also they asked me to install a new air filter located on left side of engine, the one that supplies air to the waste gate.

    Another driver is doing a run with the truck he had no problems yesterday, however today same thing 35psi - 0psi -35psi - 0psi - 35psi - 0psi and remained there for a few miles. The driver started to pull on small hill, 0psi barley made it up. He revved the engine up to 2000Rpm and got full boost instantly.

    Any advice no matter how silly it might be would be appreciated.
     
  2. Sportster2000

    Sportster2000 Road Train Member

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    My only guess would be to check the wastegate for possible sticking issues. Do you hear any sound of boost leakage when under full pressure?
     
  3. Sad_Panda

    Sad_Panda Heavy Load Member

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    Everything but the lack of black smoke screams EGR to me, but they didn't have a EGR in 2004 did they? If it isn't that, check that you got all your wastegate working.
     
  4. Sportster2000

    Sportster2000 Road Train Member

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    They did have EGR in 04.
     
  5. Dutch

    Dutch Light Load Member

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    vgt vanes could be sticking or the vgt control module is going out.
     
  6. Trouble65

    Trouble65 Medium Load Member

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    I just got back with the truck.
    She came up 0 boost twice, however each time a 'Check Engine Cpu" light came on.

    I can hear the turbo, however I can't say that I hear any sound of boost leakage.
     
  7. Trouble65

    Trouble65 Medium Load Member

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    That was going to be my next guess. Taking her in tomorrow morning. At least this time we might have a code.
     
  8. jrwork69

    jrwork69 Bobtail Member

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    Did you spin out while using the full lockers
     
  9. Trouble65

    Trouble65 Medium Load Member

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    Huh? and no!
     
  10. Trouble65

    Trouble65 Medium Load Member

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    Update:

    The unit was at cummins and they found out that the exhaust manifold pressure sensor was faulty.

    We have put on about 6,000 miles since the fix and no problems.