So I command the CP3 to 23K and I only get 12-15K rail pressure.
You would think bad CP3…

But while driving my rail pressure will hit 21-23K at times.

How is this possible?

 

What are you running for a programmer/tuner?

What all do you have done to the truck?

 

Stock, No CAI, or exhaust.
I have a Hypertech but have seen the rail pressure do this with and without it.
I have EFI Live to scan.
I keep getting a P1093 with or without the Tune.
Balance rate are all good, In Park or Drive.

I did just do a FPRV shim but I noted the rail pressure info before the shim was installed.

 

Hypertech uses fuel pressure to make power, but there are multiple injection events going on while you are driving. The hypertech is not adjusting the lower RPM injection events. So that is why you are not noticing the increased rail pressure all the way through the RPM range. Which isn't a bad thing.

If you run to much rail pressure at lower RPM's and the turbo isn't producing enough air to match the fuel you will just put out the fire. If you really want to make good power all the way through, you need the adjust the pilot fueling event. Not many people do this but it will increase horse power through out the entire RPM range.

Default pilot fueling is set at right around 5,000 PSI on my truck we did a pressure spike right at 1500 RPM to get my 66mm turbo to light we adjusted the pilot fueling right there to hit 8500 PSI and then above 2000 RPM's it returns to 5,000 PSI but all of the other injection events are modified at that point.

I hope this makes a little more sense.

 

can any body tell me is it possible to bench test a cp3, no pressure not sure if cp3 ot cracked injector.Replaced injectors 15,000 miles ago.This problem happened after a very cold night.It was in the 60's that day in teens at night,had plugged in found out heater cord was broken,heater didn't work.

 

sounds like cp3, what kind of pulesidth are you commanding?

here is a diagnostc chart you can use.

https://www.dieselbombers.com/chevy-...sure-side.html