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Two 06 6.0s With Different Problems
I have a 2006 F250 and a 2006 F550 that are giving me trouble. Both are 4wd and automatics.
The F250 has around 71.5k miles and has an intermittent start issue coming from low ICP. This started this week, noticed by a longer start time which quickly grew to a more prevalent (but still intermittent) no start/looong start. With cranking RPM's around 175rpm, sometimes the pressure will climb to the low/mid 300's and fire up. After the engine fires up, it runs normally, although at idle the IPR is in the mid 20 percentile vs the F550's percentile being in the teens. The max pressure I saw was 3400psi. Sometimes after killing it, it'll start back up without delay, it did 5 starts in a row today without trouble (waiting for ICP to bleed to 0psi, which it does quicker than my F550). It seems to be harder to get it to crank the first time than for subsequent restarts.
Undoubtedly I have a leak somewhere and I'd suspect the STC fitting. I have read about the air test, but haven't seen a clear protocol for this, anyone have a link to the procedure and expected outcomes?
Secondly is the F550 with 200.5k miles. It was in the dealer roughly 2k miles ago with a cracked injector cup. Under warranty they replaced the head and I paid for studs and BPD's EGR cooler. After ~1k miles the engine developed a very sporadic, very short miss occasionally at part throttle/light loads. The "miss" was originally a instant total loss of engine power that lasted under half a second. The people riding with me didn't perceive it. It made it out of warranty (Diesel Care Plus) by a whopping 154 miles before I made it back to the dealer. It is throwing two codes for the #2 and #6 glow plugs, but nothing related to the short/miss. The tech said it was either the PCM or the wiring harness, but it wouldn't hurt to drive on it and it shouldn't leave me stranded. Well, it hasn't left me stranded, but it has given me a 5 and 15 minute delay now.
The truck is throwing no codes (aside from the glow plugs). From cold, it starts right up like nothing is the matter and runs for 15-25 minutes before starting to "miss". It can sit and idle or drive down the road, either way the result is the same, a dead engine. The duration and frequency of the miss is no longer an occasional momentary blip at partial throttle, but it's still like the key is being cut off. I swapped the PCM from the F250 and killed the engine when I heard the first "miss," ruling out the PCM in my mind.
The FICM Logic Voltage varied from 11.5-13 volts during the miss/stumble/dying/restarting phase. The FICM main voltage stayed at 47.5-48V. After it dies, I can sometimes restart it with no problem, but now the more regular result is longer cranking/waiting/multiple tries (generating 6-800psi ICP during this time). I have bookmarked a couple PDF's with likely locations of chaffing which I will look at tomorrow. The ~15-25 minutes of flawless running makes me wonder about the wiring however. Is it possible to swap the F250's PCM and FICM to the F550 to test without issue?
FWIW, the dealership wanted $711.20 for the wiring harness and $1146.18 +$100 core for the PCM. Tousley's online price is $447.04/$880.44 respectively. They said $600 to replace the engine harness and an hour's labor to replace the PCM. Unless it's something spectacular, I'll likely do the work on both myself. The most likely exception is if the 250's problem is covered under the Diesel Care warranty and the parts/labor time to fix it make it worth buying the warranty.
Anyone have some guidance?
Thanks for your time,