Diesel "miss" heavy loading low rpm/converter lock
 

Guys I need some help please. I have an 05 with 94k and have done the following upgrades. Amsoil bypass kit, Egr delete, arp studs, powermax turbo, Driven Diesel reg return, mbrp 4", new HPOP, rebuilt trans with billet converter, rebuilt injectors to 155/75 nozzle, matts full fuel tune from gearhead, and edge cts monitor.

Since having the injectors installed, I immediately noticed a prevalent miss/stutter when the converter locks in 4th/5th. The sensation is that of running over a bumpy road. I had the sticks pulled and retested by builder. Came back "fine and flowing 155-162 @. 2.5 m/s pw. Re-installed with new washers/o-rings. Same. Checked contribution. Was told it was fine. Swapped FICM. Same. Checked IPR no oil in plug. Change pigtail on vgt. Same.
I have no idea what else to check or change short of completely different injectors. Prior to adding the reg return and injector I had no drive-ability issues whatsoever. Anyone have any other ideas???

No codes!!

Boost is steady and very consistent. No smoke when the truck is missing. I also should mention the the exact symptoms are present when I return the sct tuner to stock

As far as the converter goes, it is a billet and less than a year old and never kicks out of locked unless it downshifts or you hit the brake. Talked with my trans builder and he swears it is not converter as there are no codes and he said it would not continue to lock. I am thinking it likely be injectors or a sensor. There was no problem until the injectors went in.

Any thoughts on the injector size/nozzles (155cc with .75 over stock nozzle)?

The strange thing is that once the converter is locked (overdrive) the truck misses ONLY when you give it enough throttle to sustain the speed. If you lessen throttle it disappears and if your increase the throttle to (still keeping converter locked) it disappears as well.

Just checked the static and dynamic fuel pressure under driving loads and while the missing is occurring there is NO drop in pressure and stays steady at 65psi. Only when full boost/fuel does it slowly fall to 58psi.

Anyone had similar issues? A few things have been suggested like IAT2 but that is fine too and converter itself in which I had checked by trans builder and is also good.. I am really at a loss :-huh

I'm thinking the same thing you are. It is an injector problem. That is a classic symptom of a bad injector. Maybe have them checked by someone else? I'm not sure it will show up in testing as it goes away at higher flow rates. Good luck.

Thanks for the reply.. That's about what I was thinking. Not much left it could be I guess..but wouldn't it smoke or have/cause hard start, rough idle? I have none of those symptoms.

My last failed injector only showed the symptoms you have, plus a lack of power for the first 20-30 seconds after a cold start. Very hard to notice the second one.

All injectors are not rebuilt eqaul

call Dolph Pinkerton at penn diesel components 717-525-8709
He has all the answers

That actually sounds like injector servo problems. I had that once prior. This is different as it runs the same whether cold or hot, never issues starting cold or hot and does not smoke while exhibiting the symptoms