Hey guys, needing some advice here. First problem I've come across that doesn't answer to any of the normal fixes . . .

Truck runs fine, rail and supply pressures are pretty normal, but under hard acceleration the engine starts missing. Rail pressure dips with the misses, but doesn't drop far, maybe 2-5K, and if I back off the missing stops immediately.

I've replaced virtually everything in the high-pressure system--injectors, crossover tubes, rail assembly with sensor and PRV, and the COV in the high pressure pump. Haven't replaced the FCA but it moves easily. All parts were brand new from either a Bosch dealer or Cummins.

The miss is not directly related to rail pressure--the quicker I get on the throttle the earlier it starts missing, even if rail pressure is only 15 or 16k. However, if I ease into the throttle it will make it all the way to 24-25k before it starts.

I recently did the injectors on my truck because there was moisture around the #4 exhaust port--enough that it was visible on the head without moving the manifold. Little hard starting but nothing serious. I followed installation instructions pretty carefully but is it possible I did something wrong? It runs great at idle, starts easily, smooth right up to 3000 RPM--everything is great except when I get into it like merging onto the highway.

I would replace the CP3 next on the theory that maybe it's getting weak and can't deliver enough fuel but I don't remember for sure that the problem didn't start when I did injectors . . . . Getting a little frustrated

 

Injector harness issue?

 

Are you thinking under the valve cover or elsewhere? I'm not sure why it would only show up at high load . . .

 

I had a problem like this after installing a new fuel pump. Under hard gas it would suck air through a fitting I didn't put tape on and starve the cp3 of fuel.

 

Ok that's an interesting thought. The one other thing I did at the same time was change both filters on my AirDog. What are the chances that if one of the gasket surfaces had some dirt on it, air could get into the system? Something I can check in the morning .... Never even crossed my mind

This is good, my brain needed something fresh to chew on, thanks guys!! And keep it coming if you've had similar experiences!!

 

The popping could be turbo bark. The turbo could be stalling when you get on it hard.

 

Well, I pulled both filters on the Airdog, cleaned the gasket surfaces and reinstalled good and tight. No change.

Papa duck, I have an old 12 valve that I turned up a bit and swapped to a HE351 turbo off of a 2006, it would bark the turbo pretty easily until I made some adjustments. I'm pretty sure it's not the same thing. This almost feels like a hard stall, except that the truck doesn't die. If I stay in the pedal, it misses hard several times and smooths out but the power doesn't come back until I back out of it. Rail pressure stutters in exact time with the misses, but the PRV is brand new.


Last thing I'm going to do on the road is swap in a new FCA just cause its cheap, then ill just live with it until I get home and can do some thorough inspecting.

 

I forgot to mention the CP3 has the Industrial Injection bag-o-parts installed, I don't know anything about that kit. It was installed before I bought the engine.

 

So I've been fiddling. Pulled timing back to stock, made no change, so it's not too much timing.

Pulled duration back to stock, didn't fix but I thought it helped a bit.

If I under-torqued the injector hold-down bolts, would that impact rail pressure at all or just cylinder compression?

 

Sounds like the CP3 is the issue. It's not delivering the amount of fuel requested and it will pop and miss when this happens.