Join Date: Dec 2012
Location: North of Pittsburgh
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HPOP bad?, or one injector using too much oil
I posted before about a one cylinder miss at high rpm at mostly full throttle to get opinions about what the problem could be. Here is some more info about this problem.
Today I replaced the icp sensor and have put the truck back on the Snap On Solus scanner to watch injector pressure readings as throttle position and engine loads / rpms were played with during the drive with the new sensor.
What I have found is that during full throttle acceleration in a high gear climbing on a long and steep hill the injector pressures plateau at 2200 psi near 2500 rpm then psi goes down to around 2000 to rpm red line. The duty cycle is at the maximum 65%. Starting at roughly 2500 rpm one cylinder is definitily missing.
Also, during that acceleration time if I were to let off the throttle lets say to about 80% full, the pressures can go as high as 2600 psi but the duty cycle is at 50% up to the maximum of 65%. I did see the pressures spike up to 2900 psi for about 1 full second during one time I throttled down.
When I throttle back up to full, the pressure drops to 2000.
Would I be correct in saying that the pump is worn to the point that it cant keep up with the stock injectors?
OR, If one injector is sticking open at 2500 rpms or worn more than the others, COULD that injector be consuming too much oil and decreasing the system pressure?
All pressures and duty cycle are normal at idle, including the perdels.
How could I test this, What are your thoughts?
Early 99 F550 4x4, 6 Shift, 11 Foot Flat Bed Dump, 11000# Empty, Always Loaded or Pulling Something up to 26000# GCW
G2 Wicked Wheel - 34psi Boost On A Factory Turbo, TS 6 Chip, 4" Exh, Terminator Pump, Bellowed Up Pipes, Donaldson Air Filter Setup, Billet FPR Housing, Homemade Hutch Mod, Gauges