Cummins ISX 500 boost problems

Discussion in 'Trucks [ Eighteen Wheelers ]' started by FunkRider, Sep 26, 2010.

  1. FunkRider

    FunkRider Light Load Member

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    Jul 22, 2009
    Hamilton, Ontario
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    Driving a 04 Volvo VN670 with an ISX 500 pulling a 53ft Utility Reefer. It has terrible power, mileage and smokes a lot more than I feel it should.

    It has just over a million clicks on it but it had an in-frame and the cylinder head was totally redone. The fuel system was also redone and is all up to spec. The EGR was recently done (for the third time in 6 months, last two under warranty)

    The main noticable problem is the boost gauge fluctuates sometimes slightly and sometimes wildly. When wildly it seems to overboost and the boost will "pssshhhhht" like a gas turbo engine with a blow off valve and the boost drops off. It will do this pretty fast depending on what rpm. It also shoots huge black clouds when it blows off. This happens under (usually) under heavy load but also doesn't happen at all other times. Backing out of the pedal helps but it means climbing a hill even slower than the pumpkin trucks. Really sucks being the slowest truck up a hill when you aren't even heavy.

    Under boost it makes strange sounds, sometimes like I sucked a cat into the turbo, sometimes a buzz and sometimes just kinda like a moan. The local cummins tech are no help. I think its a boost leak but they seem to blame every problem on the EGR... I built a boost leak tester to go on the turbo inlet to pressurize the system but haven't had a chance to use it yet.

    Mileage running FL at 65-80,000 is at best 5.5 but usually averages out at 5 or slightly less after VA, WV, and PA etc
     
  2. Trouble65

    Trouble65 Medium Load Member

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    Jan 11, 2009
    Ontario Canada
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    Did your "Check Engine Light" come on?
    If there was no CEL then the problem is loss of boost through a leak.

    However I would say it's an electrical issue. My ISX in the Volvo 670 did the same, very little boost and then all of a sudden you better hold on she pulled hard and then no boost.
    I believe they replaced the boost sensor on my truck. I will have to have alook at the repair record on exactly what was done.
     
    FunkRider Thanks this.
  3. Hardlyevr

    Hardlyevr Road Train Member

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    Jul 30, 2009
    Gardners,PA
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    it may be the EGR again or the waste gate.
     
  4. Karicz

    Karicz Bobtail Member

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    Jun 26, 2010
    Chicago
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    Where is the boost sensor?
     
  5. FunkRider

    FunkRider Light Load Member

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    Jul 22, 2009
    Hamilton, Ontario
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    The truck does show "check engine ecu at next stop" on the big LCD display once and a while but I don't think the truck has a check engine light. Same thing I guesss.

    good question...
     
  6. mrdevildog

    mrdevildog Light Load Member

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    Feb 23, 2010
    Heber Springs, Arkansas
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    the boost sensor should be located on the air intake, driver side of the engine, will be two sensors right next to each other, a intake air temp sensor which is a two wire sensor, manifold pressure sensor(boost) which is a three wire sensor. sometimes the sensor can be fun getting out and part of it will break off in the intake so be carefull.
     
  7. Diesellee

    Diesellee Bobtail Member

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    Jan 12, 2011
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    I am having the exact same problem. Did this ever get squared away? Anybody else with this issue?:biggrin_2552:
     
  8. Pappa Bear

    Pappa Bear Light Load Member

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    Dec 20, 2010
    Springfield, OH
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    A very likely culprit is the turbo actuator. There is an air line that goes into the top of the turbo. This controls the actuator. Sometimes the seals will go bad and it will begin to leak air pressure. If you are loosing air here or threw a hole in the line the turbo will not operate properly. You can get a new actuator for around $300.
     
  9. Diesellee

    Diesellee Bobtail Member

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    Jan 12, 2011
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    Hey papa thanks but my truck is an 09 with VGT turbo and I don't believe it's controlled by air? But from what I gather from more reading it has to be manifold pressure sensor. Dang boost gauge moves around like the tachometer. There is not smooth controlled power with the pedal. If you can imagine holding your foot on the pedal expecting smooth delivery of power, my truck cuts in and out and boost is jumping around. Im probably just gonna by a new sensor and put it in for the he'll of it.
     
  10. Pappa Bear

    Pappa Bear Light Load Member

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    Dec 20, 2010
    Springfield, OH
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    You're right the newer ones are electric. I suppose it could be a boost sensor or a manifold pressure sensor. I would take both out and just check them to see if they are plugged up with soot. Mine is an 06 and it has a small tube that goes from the exhaust manifold to the bottom side of the thermostat housing where the manifold pressure sensor is. You might check and make sure it is not plugged. Also check the connections to the sensors for corrosion. Be careful taking the sensors out they can brake. PB blaster is your friend.
     
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