Idle Issues F350 (diesel)

Discussion in 'General Discussion' started by Homunculi, Oct 24, 2015.

  1. Homunculi

    Homunculi Monkey++

    looking into an idle issue on my 6.0 powerstroke
    a customer at work and i were talking about the rolling idle issue ..
    he told me it could be the ICP sensor and i am not sure ..

    the issue i am having is :
    on cold start .. some times extended crank ... and idles fine ..
    after it gets to operational temp runs ok till i stop and the idle will drop as low as 500 rpm
    then spike to 1100/1200 rpm .. and in some cases stalls out ,,
    other times it will drop to 500 rpm and i will get no response from the accelerator at all

    in all cases .. shut down and wait 10-20 sec restart .. all ok for a while

    the one from the dealer is in the $350-400 range .. and koi has one for $170

    does anyone know about this before i start tossing money at a problem i am unsure about ...

  2. ghrit

    ghrit Bad company Administrator Founding Member

    First question I would have is whether or not the fuel filters are fresh. Then, since I have no idea how the engine speed is governed, I'd want to know whether it's done by hydraulics or electrical servo motors. If hydraulic, I'd want to know if the oil filter was clean.

    Might also look for air leaks on the suction side of the fuel system. Again, without knowing if it has a two pump system (tank transfer to injector pump or direct single pump, tank to injectors) it's a SWAG from here.

    Pretty much a guess from me.
    Ganado and Georgia_Boy like this.
  3. Homunculi

    Homunculi Monkey++

    did a fresh oil change in august ... new fuel filters back in april ...
    Ganado likes this.
  4. techsar

    techsar Monkey+++

    Before you even consider throwing parts at an undiagnosed issue, have it checked out by a shop that is competent with Powerstroke engines.
    Some things to look at...duty cycle on IPR, actual ICP pressure, fuel pressure, any related DTCs...

    Common issues are, in no particular order: faulty injector, leaking feed tube orings, failing high pressure oil pump, ICP sensor, IP regulator, deteriorated wiring harness, failed IPR screen, IDM output voltage. Also, if the low side oil pressure takes too long to build, it is quite possible a lifter roller has come apart...which gets picked up and gouges the oil pump rotor, cover and engine front cover...can you say $$$$$$? BTW, the front engine covers are on national back order with no predicted delivery date...

    ETA: Don't overlook the water drain on the "fuel conditioning module" located on the left frame rail below the driver. There is a tendency for the separator chamber to get filled with sludge, which will not only block the fuel flow but can (and will) damage the fuel pump.
    Last edited: Oct 24, 2015
    Ganado, kellory and Yard Dart like this.
  5. Homunculi

    Homunculi Monkey++

    ETA: Don't overlook the water drain on the "fuel conditioning module ...

    cleaned out and put a new WIF sensor in last year ...
  6. Homunculi

    Homunculi Monkey++

    might have added to the post .. that when it is rolling the idle like that i have unplugged the icp sensor than the idle smoothed out ... and it behaved ... that is one reason i am thinking it is the icp sensor
  7. techsar

    techsar Monkey+++

    That could be, but it is not guaranteed. My suggestions above were to reduce the chances of you throwing hundreds of dollars away :)
    When you unplug the ICP sensor, the ecm sees 0 psi. This will cause the IP regulator to dump off less oil to raise the high pressure oil pressure. Low engine oil pressure, a faulty regulator or other items can all contribute to your scenario. That's why you should look at what is going on in the entire system first.
    Homunculi likes this.
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