MAXXFORCE DT 2012 No Power No Boost Slow Throttle

Discussion in 'International Forum' started by Legacy_Lopez, Mar 1, 2024.

  1. Legacy_Lopez

    Legacy_Lopez Bobtail Member

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    I have a 2012 Maxxforce DT twin turbo model that has a super slow throttle response. If you test drive it takes forever to come up to speed but once the turbos get going the power seems to come back. when the truck shifts it loses the turbine momentum and just falls back on its face. We have checked the turbos for coking and cleaned them. We checked and put a new small hose for the turbo solenoid that sits on the small turbo and found the original line to be cracked. thinking that would fix the issue we test drove it and it did not change at all. that truck starts great in cold weather and idles very good but just has no power at all and the boost pressure never gets above 13psi back pressure is what throws me off because it never climbs above 20psi the fuel pressure is rite around 75-80psi and I know spec is 90 but I checked other trucks that have come through the shop, and all read lower the that and run great. DPF has been swapped with a clean unit and same thing. the EBPV has been checked and is free and clear the throttle body is flat and not creating a restriction. I am really lost with this truck. the throttle response is so slow even with it in neutral it takes forever for it to come up past 1800 rpm. any help or suggestions would greatly be appreciated
     
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  3. Inderjit

    Inderjit Medium Load Member

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    Being its a 2012 it wont be a Maxxforce DT it should be a Maxxforce 9 or 10.
    Have you had a good look at the intake hoses and the charge air cooler?
    You could have a boost leak. Depending on the HP rating you should get over 30 PSI boost.
    Any fault codes? Do you have a scanner to check the injection pressure?
    Could you post the last eight of the VIN or PM it to me.
     
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  4. Legacy_Lopez

    Legacy_Lopez Bobtail Member

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    Then I would assume its a 10. valve cover says maxxforce DT Yes I've done a boost pressure test we are a diesel repair shop that primary works on Cummins cat Paccar Hino Isuzu stuff so this is throwing us for a loop as we don't typically work on these engines much. It says 230HP. we have NEDS and a snap on scanner that we use ICP desired and actual match pretty good +-150psi no fault codes
    VIN - 1HTMMAAL5DH202198
     
  5. Inderjit

    Inderjit Medium Load Member

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    Fuel pressure should be 80 to 100 PSI so your pump is good. The quick coupler
    on the filter/pump module is fed from the outside or dirty side of the filter.
    If the filter is restricting fuel to the injectors it wont show as a pressure drop.
    Has the fuel filter been replaced?
     
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  6. Legacy_Lopez

    Legacy_Lopez Bobtail Member

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    Yes, the fuel filter has been changed. I am honestly at a lost with this truck cause i hate throwing parts at truck I've always put pride in not doing that but this is seriously throwing me for a loop! now it's doing something it wasn't when it was brought into the shop. when you start it for the first 10 min of it running you can't accelerate or anything it just doesn't do anything other than idle. after about 10 min it will slowly allow the throttle to come up and rite around 1900-2000 rpm it gets this bounce in the RPM really weird
     
  7. Inderjit

    Inderjit Medium Load Member

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    There is no check engine light when it's refusing to accelerate?
    Trucks with the DT and Maxxforce engines us a "Clean Power Harness" from the batteries to the engine ECU.
    The power harness can have several 3 pin plug connectors depending where the batteries are. One ground and two power. This harness is prone to having the connectors in the plugs melt and/or loose their grip on the mating connector. The two 40 amp fuses in the battery box can also have connectivity problems. The harness also can rub through the insulation and the wire corrode away. When the power supply starts to fail the truck can develop a lot of weird running problems.
    Locate the harness and disconnect it at the batteries and cut all the zip ties and inspect it right up to where it connect to the chassis harness near the firewall.
    If there are no problems with the power harness I would contact a dealer and see if they can reflash the engine ECU with the latest software.

    I had a truck that used to have to take a 25 minute ferry ride across the an inlet. The ferry company had a "NO Idle" policy. When the ferry got to the dock there was a 15% grade you had to drive up. After the truck was started it would idle a bit rough and when you tried to drive up the steep grade it would shake and run really rough and refuse to go up the hill until it had warmed up for about 5 minutes then it ran fine. An ECU reflash fixed it.

    If the Batteries go dead or are left disconnected for a period of time the ECU can loose some of its programming. If a battery disconnect switch is installed the ECU keep alive power has to remain on the battery side of the switch.
     
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  8. Legacy_Lopez

    Legacy_Lopez Bobtail Member

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    No check engine light. Ill check those connections and get back to you. I know exactly which ones you're talking about! I guess I'll make an appointment with Mccandless and see if I can get it flashed to the latest software. Have any more ideas as to where to continue as far as the low power no boost conditions?
     
  9. Inderjit

    Inderjit Medium Load Member

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    Hopefully a reflash and if the harness needs repair it will run properly again.
     
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  10. Heavyd

    Heavyd Road Train Member

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    Sometimes the air to air become plugged, or the intake heater grids to cause issues like this. You can remove the air the air pipe on the left side, and run the engine with the intake open and snap the throttle to see if it will rev up normally. If not, you need to get a small mirror and look down the intake and check the heater grid for plugging.
     
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  11. Legacy_Lopez

    Legacy_Lopez Bobtail Member

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    I
    so I have actually removed the cold side CAC thinking that it could have been plugged, checked it, and no difference whatsoever that is actually when the no revving started happening I have not actually checked the heater. Grid for excessive carbon buildup, but will do first thing Monday morning before taking it to the dealer for a reflash any other suggestions?
     
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