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Thread: C-12, no power low boost.

  1. #1

    C-12, no power low boost.

    I have a 2003 T800 with a C-12 that we just put into service, it is very low on power. I fully realize that a C-12 isn't over powered, we have other C-12 powered units doing the same job every day. I can't get over 45mph at 80K gross.

    We added a boost gauge and I believe the problem is boost related. The most boost we can get out of it is 13psi. The engine sounds fine, no misses or other odd noises etc.

    So far we have done the following: Leak down test on air to air, visually inspected all boots and clamps, visually inspected turbo from air side, changed fuel and air filters. Checked ECM for any fault codes. Visual on exhaust has no smoke at all at WOT.

    Next on the list is to test fuel pressure.

    If anyone has any other ideas to check or try, please let me know.

    Someone on another forum mentioned air blowing thru the compressor or something, please help me understand this better or how to test. (the compressor does build really slow related problem??)

    We also have a sister truck to this that needs an inframe that we can rob parts off of for testing purposes if anyone has any suggestions.

    Thanks for your help.

  2. #2
    Senior Member
    Join Date
    Dec 2015
    Location
    Warwick New York
    Posts
    155
    My two guesses are :
    1 Fuel pressure
    2 Derate tune.

    How does it run empty?
    Perky or like a dog?
    Of the pressure test comes back good, can the ECU be borrowed from the other T800?

  3. #3
    Thanks for the reply Jason, Pretty doggy empty too, but acceptable. We will first test fuel pressure, if that is good, we will swap ECU, which is definitely doable. Probably will be Monday.

  4. #4
    Senior Member
    Join Date
    Dec 2015
    Location
    washington, st.
    Posts
    763
    When you checked the turbo did you check the radial runout? Side to side play. Disconnect the intake hose from air compressor and plug intake on manifold. Run and see
    what it does. Boost sensor? Did you use soapy water on the air charge cooler when you tested it. Did you check fuel lines for restrictions? Primer pump check valve roll over?

    Truck Shop

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