Low Turbo boost

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Rideandrepair, Sep 2, 2023.

  1. Rideandrepair

    Rideandrepair Road Train Member

    16,420
    53,685
    Aug 8, 2015
    0
    My 1999 12,7 only gets to 10-15 max. Real dead at lower RPMs. I’m guessing it’s the sensor. Does that sound right? Same symptoms as when my last Truck had that problem. I didn’t have a boost gauge though. Changed fuel filters didn’t help. No codes. Don’t recall any codes last time on last Truck.
     
  2. Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  3. beastr123

    beastr123 Road Train Member

    2,607
    21,471
    Jan 2, 2014
    Moose Jaw SK CAN
    0
    Do a pressure test from the turbo to the engine intake including all boots/hoses. Spray soapy water over it all and look for bubbles.
    will give you the diy instructions and build list.
    Any drop of more than 3 or 5 lbs per min should be addressed.
    test to about 25 lbs for a 12.7.
     
    Rideandrepair Thanks this.
  4. max954rr

    max954rr Bobtail Member

    11
    8
    Mar 29, 2022
    0
    What engine do you have?
     
    Rideandrepair Thanks this.
  5. beastr123

    beastr123 Road Train Member

    2,607
    21,471
    Jan 2, 2014
    Moose Jaw SK CAN
    0
    the only engine designated as a 12.7 is a Detroit manufactured between 1987 and 2011 also known as a "Series 60"
     
    Rideandrepair Thanks this.
  6. Rideandrepair

    Rideandrepair Road Train Member

    16,420
    53,685
    Aug 8, 2015
    0
    Yeah it’s a Detroit. I have a homemade leak tester. Everything’s relatively new. I just wondered how much boost if any the turbo produces, if the sensor is bad. Seems like it has to produce some since it’s spinning. I’m going to unplug it, and see if boost is the same. Just don’t want to buy a sensor if I don’t need it. I don’t know how the sensor controls the turbo, since the turbos all mechanical. Last time I changed one, a bolt broke off in the manifold. It’s a common thing. Considering it’s never been changed. Might be a problem. I’ll use some heat and PB blaster this time.
     
  7. MRMTRANS

    MRMTRANS Light Load Member

    234
    273
    Apr 28, 2015
    0
    The volume from the pitch of the turbo winding to the max is usually noticeably louder when there is an air leak in the air intake system.
     
    Rideandrepair Thanks this.
  8. Rideandrepair

    Rideandrepair Road Train Member

    16,420
    53,685
    Aug 8, 2015
    0
    Update. Bought a turbo sensor online from Lab works for $20. (A friend commented I should have bought 2) Lol. Anyways same problem. Found a leak in the big hose from cac to manifold. So obvious, yet I missed it. Oh well at l at least didn’t pay $160 from the Dealer. Now I have a spare boost sensor. New hose is $375, on backorder. Plan on a 4” steel tube with 2 new boots. Meanwhile it’s duct taped. Yep. Also changed all the fuel lines. Been postponing it forever. Suspect it’s been sucking air causing it to sputter sometimes. Had all kinds of problems after changing them, kept losing prime, replaced o rings in check valve, and stretched the spring a bit. No help. Noticed a lot of air bubbles in tanks. I had to redo a couple of the fuel lines. They were sucking air, and bleeding down within 30 minutes. Finally got everything sealed up good. Seems to be running pretty good now. Didn’t hurt the check valve stretching the spring out. It’s working good. Holding prime over night. Intermittent sputtering issue might be solved. I hate to mention it and jinx myself. Still have a very small amount of bubbles in tank. Will soon know for sure. Hasn’t sputtered in 1800 miles so far. Trying to keep the boost below 20 lbs. That’s when the duct tape blows out. Lol.
     
    Last edited: Sep 20, 2023
    BoxCarKidd and Crude Truckin' Thank this.
  9. Rideandrepair

    Rideandrepair Road Train Member

    16,420
    53,685
    Aug 8, 2015
    0
    I’ll do one after I fix the major leak. Cac is fairly new. 200k miles. Avtek brand. Anyway Thanks. You were right about the cause.
     
  10. beastr123

    beastr123 Road Train Member

    2,607
    21,471
    Jan 2, 2014
    Moose Jaw SK CAN
    0
    Hose clamps and tarp materiel may help contain boost to 25psi if it is the pipe and can be welded by a competent welder.
    The hoses are not expensive and you should carry a spare, and I always double clamped each hose.
    Silicone Hose Assembly 4" X 6.5" ID Blue Cold Intake Charge Air Cooler
     
    Rideandrepair Thanks this.
  11. Rideandrepair

    Rideandrepair Road Train Member

    16,420
    53,685
    Aug 8, 2015
    0
    It’s on the cold side. One big 4” rubber hose about 3 ft long. $387 at Dealer. Need to get a 4” pipe. Pvc aluminum, anything. Cut ends off rubber hose for now. Eventually get a formed 4” aluminum pipe. Use the ones you’re talking about. I carry one of those. Have blown them before. Have blown the 1” compressor hose once. Never this big original rubber hose. Be better w/aluminum pipe. Not paying $400. Lol. $88 online fits Cascadia. Couldn’t find one for FLD. Maybe get the part# look again. I’ll figure something out.
     
    BoxCarKidd Thanks this.
  • Truckers Report Jobs

    Trucking Jobs in 30 seconds

    Every month 400 people find a job with the help of TruckersReport.

  • Draft saved Draft deleted