Diesel Bombers - Intermitent Miss - A Troubleshooting Challenge!

2005 F250 FX4 6.0L w/ 114,000 miles

Thanks in advance for your help, and I apologize for the long post. My mechanic background is in motorcycles, and although I know how to turn a wrench, I am a little lost when it comes to Diesels. Just trying to give you all the info I can.

I don’t hot rod or abuse my truck. Really, other than pulling an occasional trailer, I drive it about like a 1/2 ton truck. The only reason I have a programmer is for fuel mileage and I use the factory “Street” setting for normal driving.

It all started with a miss and some blue smoke out the tail pipe. My STC Programmer pulled a code for cylinder #5 Contribution fault (P0275). I self diagnosed (bad idea) the issue as an injector. I had been wanting to do an EGR delete and a few other mods so I called up River City Diesel and ordered 4 injectors for the passenger side (1-3-5-7), and the parts to complete the following (head job and studs are next on the list).

-HPOP T-Connector / Seals
-Blue Spring Upgrade
-RCD Oil Cooler
-Intake Gaskets
-RCD EGR Delete & Up-Pipe

All went “mostly” well, and with the help of a few fellow mechanic friends, completed everything in a Saturday.

Now the fun part……… The miss is still there! And this is the bizarre part, I have figured out how to make it NOT miss. If I turn the key on and wait for the annoying chime to ding at least 3 times before starting, EUREKA! No miss! I drove 2 days with no miss this way. No matter hot or cold if I get in the truck and start right after turning key forward it will almost always start missing instantly and producing a beautiful plume of blue smoke. Had a friend plug it into his computer and while missing we can turn off injector #5 (while missing), smoke stops and idle remains the same. Turn injector back on and smoke reappears. Shut truck off, wait a few min, turn ignition on, wait for at least 3 dings to start and miss is gone.

Another thing to note, if you start truck, leave it missing and drive, sometimes the miss stays at idle over the trip and sometimes it goes away, either way it never misses at highway speeds, or at least you cannot feel it. I unplugged injector #5 just to see what it feels like at highway speeds and it shutters and shakes like there’s no tomorrow. So I can say when it is missing at an idle, it is definitely working at least partly when cruising.

Any help appreciated!