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Thread: I Need Of Some Guidance /Were To Start My Search

  1. #1
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    In Need Of Some Guidance /Were To Start My Search

    Not to sure where to go from here. I have been having a rail pressure issue and need help figuring out what the possibilities could be
    i did flash in a factory tune and seems to have some of the same issue just doesn't seem as bad


    the problem i'm having is that the rail pressure seems to drop 4-5k psi bellow commanded when i go to wot
    on lower throttle it seems fine it only happens when i go wot
    the truck is a 2003 250hp 5 speed truck

    injectors have around 150000 km
    everything else has 608000 km
    fuel filter get changed every oil change
    around 12000 km intervals
    fca was replaced last year
    i have a rail plug installed
    cant find any obvious leaks on the high pressure side
    i am planning on installing a fuel pressure gauge for the lift pump in the very near future
    not to sure if my cp3 is getting tired
    seems to have started in the last 4-5 months
    i have had this set up run 26k psi rail pressure before with out any issues

    this is a screenshot of what's happening, the log file and the tune being run
    hp tuners log screenshot.png
    21-07-02 20-10-06 clean up tune 25.hpl
    2003 personal truck (cleaning up tune) 25.hpt

    this is factory tune with the pedal map changed and some of the limiters gone

    Log:21-07-03 09-20-08 Factory optimized tune.hpl
    Tune:2003 stock file optimized (rail pressure test).hpt
    Last edited by abgreenmachine; 07-03-2021 at 04:24 PM.

  2. #2
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    I did notice today that my rail pressure isn't spiking on shut down like it used to
    Im thinking something might be loose enough to leak at higher pressures only

  3. #3
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    Looks like the cp3 isn?t getting enough volume to keep up at the commanded high load fuel. You could turn up the base duty cycle to get the FCA to open up some more but it?s not going to help much. Tired lift pump.

  4. #4
    Advanced Tuner MAIDENCR's Avatar
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    I have a costumer that even with a fass rail pressure would never go above 10kpsi...for now injectors are on bench and some are in bad shape....will se with better injector if cp3 can keep up
    03 cummins,175% flux injectors,dual cp3,s467.7/83 1.00
    Nv5600 with valair triple disc clutch

  5. #5
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    that's what i'm hoping for wont really know until i get a gauge for it
    dont really feel like replacing the cp3
    on the factory tune it seems to be alot better with the lower fuel demand rail pressure seems to hold commanded pressure

  6. #6
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    got the lift pump pressure gauge installed this weekend
    she idles around 9-10 psi. At wot she gets down to 3-4 psi when getting close to 3k rpms, anything under 3k rpms it stays around 5 psi still at wot

    cruising hwy she stays around 7.5-8 psi

    is this fairly normal for the stock in tank pump??
    Last edited by abgreenmachine; 07-18-2021 at 10:21 AM.

  7. #7
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    Pretty normal depending on how aggressive your tune is

  8. #8
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    So then either cp3 is tired and ait keeping up anymore or injectors are starting to go or I got a high pressure leak somewhere

  9. #9
    Advanced Tuner dhoagland's Avatar
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    Quote Originally Posted by abgreenmachine View Post
    So then either cp3 is tired and ait keeping up anymore or injectors are starting to go or I got a high pressure leak somewhere
    Does it start right up in the morning? If so to me that points to cp3.
    There are procedures for return flow rate testing that separates the injector and pump return flow.
    2011 Camaro 2SS Convertible L99 Bone Stock for now
    2003 Dodge 2500 5.9 Cummins QC 4x4. Airaid, 2nd Gen Intake, Grid Heater Delete, D-Tech 62/65/12, Magnaflow. Bully Dog: Propane Injection, Triple Dog W/Outlook Crazy Larry. Edge EZ, BD Flow-Max, 48RE: Sonnax Sure Cure/Transgo combination, Derale turbulator, billet input, Triple Disc, Super servo, 4 ring Accumulator. :beer

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    Quote Originally Posted by Jim P View Post
    Pretty normal depending on how aggressive your tune is
    Gonna repeat, would underline pretty normal if mobile version of the forum allowed.

  11. #11
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    Turn up your base duty cycle in the region rail starts to drop off. Your low side fuel is pretty normal.

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    If still struggling to keep up with demanded pressure at WOT, swap out your PRV for a new one set at a higher relief pressure.

  13. #13
    Advanced Tuner dhoagland's Avatar
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    Quote Originally Posted by Jim P View Post
    If still struggling to keep up with demanded pressure at WOT, swap out your PRV for a new one set at a higher relief pressure.
    Hey Jim
    I believe he has a Rail Cap installed
    2011 Camaro 2SS Convertible L99 Bone Stock for now
    2003 Dodge 2500 5.9 Cummins QC 4x4. Airaid, 2nd Gen Intake, Grid Heater Delete, D-Tech 62/65/12, Magnaflow. Bully Dog: Propane Injection, Triple Dog W/Outlook Crazy Larry. Edge EZ, BD Flow-Max, 48RE: Sonnax Sure Cure/Transgo combination, Derale turbulator, billet input, Triple Disc, Super servo, 4 ring Accumulator. :beer

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    Yep, missed that on the first post. Scary, rail caps are bad news bears for injectors.

  15. #15
    Advanced Tuner dhoagland's Avatar
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    Quote Originally Posted by Jim P View Post
    Yep, missed that on the first post. Scary, rail caps are bad news bears for injectors.
    Agreed
    2011 Camaro 2SS Convertible L99 Bone Stock for now
    2003 Dodge 2500 5.9 Cummins QC 4x4. Airaid, 2nd Gen Intake, Grid Heater Delete, D-Tech 62/65/12, Magnaflow. Bully Dog: Propane Injection, Triple Dog W/Outlook Crazy Larry. Edge EZ, BD Flow-Max, 48RE: Sonnax Sure Cure/Transgo combination, Derale turbulator, billet input, Triple Disc, Super servo, 4 ring Accumulator. :beer

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    Rail caps are meant for racing applications where extremes are being pushed only

  17. #17
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    Truck starts and runs like a champ no issues except for wot she just won't hit commanded

    I guess I'm going to be looking at getting a higher pressure prv asap. Any good suggestions???
    I was under the impression that they weren't that bad for something stock
    I guess I was wrong

  18. #18
    Advanced Tuner MAIDENCR's Avatar
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    Probably injectors may have some return!
    03 cummins,175% flux injectors,dual cp3,s467.7/83 1.00
    Nv5600 with valair triple disc clutch

  19. #19
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    How high of a set point you go for the PRV depends on your peak target pressure, minimum I would start with is 2000bar from Exergy that way you can comfortably run up to 180mPa and still maintain relief for large spike events. Rail plugs are a race item where every single mm3 of fuel and pound of pressure matters. Your stock rail pressure sensor doesn?t read about 180mPa and with the rail plug you can potentially be subjecting your injectors to shocks of 270mPa or more with zero relief or say your FCA fails open and your injector pump is pumping full bore pressure to your injectors without any form of relief... they are not a healthy item for non race dedicated engines.

    You can get injector and injection pump flow return rates tested, there is a general range of return fuel flow that should be seen but bench flow tests are the best.

    Your low pressure side is good and has room that you can try increasing base duty cycle in the region that it falls off.

  20. #20
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    This morning I had the truck miss and sputter really bad with lots of white smoke around 1800-2000 rpms and part throttle. Only happened once on my 35 min drive and I noticed it did it once last week but I didn't get a chance to see if it was smoking or not
    Im starting to think its the injectors that are going bad and time for an upgrade