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32 Posts
Discussion Starter · #1 ·
To give you some back ground, 2009 6.7 cummins, fully deleted with DRD tunning using MM3, 128k miles and G56 tranny. Recently bought the truck and had an ECM failure while flashing computer with the DRD tuning. Bought a reman computer from reputable source. Installed ECM, flashed tuning on the ECM and now I am having issues with the rail pressure.

From the MM3 my actual rail pressure is 12k or so PSI while idling with it going to 14k will driving down the road, Truck has hardly any power at all. From the MM3 i have desired rail pressure and it shows just a touch below 6k PSI at idle and increases with throttle input like one would expect. Also i can pull up the PID for FCA duty cycle and im getting 0%. Currently while idling every now and then it will have a decent miss to it that seems inconsistant and I dont notice anything on the rail pressure readings. Current codes are P0251, P1012 and P000F.

Im assuming the P1012 and P000F codes are due to the high rail pressure at idle.

So far I have replaced the fuel filter (it was pretty bad and needed done anyways), replaced the FCA and rail pressure relief valve (both new Bosch units), measured the resistance of both wires going from the FCA to ECM (both under 0.5 ohms), Voltage to FCA with Key in the On position is right at 4 volts.

Completely at a loss for what to do next. I feel pretty confident in the new ECM, i feel that way due to me getting 4 volts to the FCA and the MM3 shows desired rail pressure (what the ECM is commanding?) and that is right where it should be. Prior to all of my issues the truck has a single EFI live delete tune on it and ran 100% perfect with no codes to my knowledge

My only thoughts is maybe the FCA is defective out of the box? but with it unplugged youd think id get 23k PSI rail pressure or so i dont know??

Maybe my CP3 went out? truck did sit for almost 2 months while I worked through the ECM issues (took so long due to working full time and then part time student)

Ill probably remove the wiring harness and start going through it but everything looks like its in pretty decent shape.

Any help will be greatly appreciated!!
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