96 runs rough and lacks power after 15 minutes or more of expressway driving.
 

My 96 F-350 has an issue that's leaving me stumped. A little history. I rebuilt the engine about 15,000 miles ago. I had a head gasket fail on me about 1,000 miles ago. (Defective gasket. The manufacturer took care of getting me a replacement.) Since then, I haven't done any expressway driving. I took a six hour trip a bit back and noticed that after driving for 3 hours, I got off for fuel. It sounded like it was missing on 1 or 2 cylinders and had a lack of power. By the time I got to the station, it cleared up. No check engine light, no smoke, good boost and no other problems. It only happens after driving at 75 and above 2100 rpm and I get off the highway. It seems to clear up and smooth up at high rpms. I can drive 55 all day long with no problems. It doesn't matter if I'm towing. Another problem it has is after setting for 10 minutes after driving, it has a very hard start. If it's right after I shut it down it will fire right back up. If it's an hour after I shut it down, it will start up fine. Starts great in the morning. My HPOP was old and tired, so I just replaced it and the IPR valve after this problem showed up. It didn't help. My fuel filter has 500 miles on it. There is no engine oil leaking into the fuel. It doesn't matter what kind of fuel I use. The only codes it had was one for Injector pressure above/below desired. It's gone now. One for my EBPV because I took out the valve. And one for the back pressure sensor. I'm leaning towards a bad injector o-ring or a worn fuel pump. I've got a trip coming up to Colorado and have over 3000 miles to go and need this problem solved. Sorry for the novel. Just trying to give you all the info. The trucks details are below. Thanks.

Still running the mechanical pump? I doubt thats your problem but you might look at an electric fuel system.

Problem sounds like a HPO issue. Need someone to run a buzz test, contribution test and a rotational value test...

Ran a buzz test and contribution test. I've got a Solus. I don't believe I've seen the rotational value test. Do you have more info on it?

stupid question but what brand and weight oil do you run in it and have you checked it to make sure it is full?

Royal Purple 15-40. I've been running it for a while now. And I topped it off after the HPOP change earlier this week.

how many miles are on that oil change? have you been running that oil from the beginning of the new motor?

i am thinking of oil foaming at higher RPM's for extended intervals will take a little while to get any air out of the injection system at a lower RPM hence the rough idling after the high speed cruise like you stated.

not having the right anti-foaming additives in the oil can cause this or old oil with depleted additives can cause this. you haven't ran any additive with the oil like Lucas have you?

I changed the oil when did the head gasket. After the rebuild, I started with Rotella and switched over after my third oil change at about 3000. And I haven't ran any Lucas or other additive, just oil. I have been running a small amount of two stroke oil in my fuel. A ratio of 200:1.

It sounds like foamy oil to me. I have had terrible experiences with foamy oil that I could not just change away. I believe It had something to do with silicone used in repairs. Seemed to be constantly depleting anti-foaming agent in new oil. I didn't figure it out until I sent a sample in to be tested.

After thinking it over and doing some research, I think you guys are on to something with the oil. I found some info last night I found that Navistar puts in a one-time anti-foam that netralizes the reaction between the two. When I rebuilt it, I was unaware of it. Tomorrow I'm headed to my local International dealer and pick up some Fleet-rite anti-foam. That's what I've found being recommended. Perhaps this lot of oil I got had something different about than the last stuff I got. I'll try this first, and if it doesn't work I'll ditch the Royal Purple altogether. (Dear Lord, I hope it doesn't come to that.) Thanks guys! I'll keep you updated.:tu:

Found the Fleetrite supplemental anti-foam at my International dealership. 5 bucks a bottle. My Ford dealer had no idea what I was talking about. Took it down the highway at 55 and had noticably lower etgs. When on the expressway for a about 10-15 miles and looped around and came back. Pushed 85 most the way and noticed a big improvement. I'm headed down to Indiana this weekend. We'll see if it clears up more. If not, goodbye Royal Purple. I'll post the p/n for the anti-foam for others.

Here's the p/n CH1824392