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Started having this problem after a 400 mile trip from Phoenix to Albuquerque. My truck will randomly die on me now. From what I can see it seems to happen on when at zero throttle, and it's only intermittent. All that I can see so far is that everything leans way out. I finally caught it in a log file. In this case it happens right before it went into DFCO. You can see how the AFR goes to full lean just before DFCO is enabled, which is not normal. I have looked at other log files and generally spark cuts first, then I see IDC go to zero, then I see AFR lean out. In this case, AFR leans out first, even though IDC is still at 2%.
Does this seem like a fuel pump issue? After I pull over I shut the ignition off, then turn it back to run and check fuel pressure, and it's fine. I have not yet looked at fuel pressure right when the truck dies, but I would think that if the pump quit working that it wouldn't start again. It usually takes me 2-3 tries cranking, turning off the ignition, turning to run, then cranking again to get it to start. Once it starts, everything seems normal. This issue seems to happen once or twice a day.
I have also attached the log file, this issue starts at frame 988. Tune file is also attached.
It's also been getting increasingly difficult to start after sitting for awhile. Took me about 5 tries leaving work this morning, and about the same number leaving work to go to lunch. Fuel pressure is good when this happens. Just sits and cranks with no fire.
Well it intermittently idles like **** now too, feels like it has a miss. Looks to be rich, but not rich enough to make it feel like it has a miss. Only in the 12.5:1 or so range. I'll mess around with the idle tuning a little bit. I decided to try and disable DFCO also and see if it changes anything. This is extremely frustrating.
I guess it would not be an individual coil pack, that would not kill the truck. it has to a wire running to the coils, possible ground issue? maybee a body ground has come loose. your alarm has been acting up to. just thinking out loud.
The issue with the alarm is in the interior fuse panel on the driver's side of the dash. I've had the same problems with it in the past...just a loose connection somewhere. I'm 100% sure that it's not related to the other problems I'm having. I'll have to check the other grounds.