I’ve been driving my truck as a daily for the last 3-4 weeks for work, pulled my 5th wheel a couple states over to live in while working. The last 3-4 days it’s had a weird “bog” when it starts up. Glow plugs kick on, truck spins right over and fires, then within probably 2 seconds of starting it drops down closer to 500 rpm and instantly recovers to 650.

if it’s the first start of the day it spins right over and doesn’t do the bog but it doesn’t roar to life like it always has it just comes up to 650 and stays there.

Since I’m away from home for work I don’t have my shop and all my tools, nor do I have much time to work on it so I’ve been kinda shooting in the dark.

initially I thought weak battery. I’ve tested each battery 3 times with 3 different testers. All test good. Then I thought alternator, changed it no change. Drove it up to Orielly, they put it on their tester, kicked up starter issue, changed it, no change.

I’ve got a sound system in there, thought maybe the amp was causing some sort of issue, pulled the fuse, no change.

thought maybe the AC compressor was having an issue, shut off AC, no change.

when I was swapping alternators around I checked the idlers, tensioner, water pump, ac pulley, no issues all spin and aren’t making noise.

fuel pressure is 60psi, then I thought maybe the filters are plugging, they got 12k on them so I changed the fuel filters. No change.

Changed the CPS, it did have a CPS code stored at some point but that didn’t change anything either. It’s the motorcraft CPS.

no fluid leaks of any kind.

im not seeing any other codes besides the exhaust back pressure now, but thats been deleted for years and its had that code for years.

data on the CTS shows the same as it always has. Screenshot of hot idle attached.

im supposed to head home with the 5th wheel in a few days and id like to resolve this beforehand.

going down the road it seems to still run strong, it hasn’t had a load on it since this started and it won’t until I hook the 5th wheel back up to head home.

 

Hot idle

 

When did you get fuel? If it has some water or junk it may just need some miles to run it out. If it still starts, the data looks good, and runs well then I not sure I would over stress about it. I get it. You are looking at some time on the road and you don’t want it to break down, but it doesn’t look like it had any significant symptoms.

 

i put about 60 gallons in it at the Murphy oil out in Indiana a week or so back. Plan was to put enough in there to get me pretty much home. It’ll take awhile to run that out on the way home. Would sure be nice if that was the case.

I put diesel kleen in the fuel as well.

i add fuel to the 100 gallon tank in the bed and have a electronic valve i switch on an off to dump it in the midship tank. The midship was probably 1/4 tank when I got that fuel so it’s full of that Murphy fuel now.

 

Datalog IPR% duty cycle ,RPM, ICP PSI on a cold start and show us the CSV file.