I have a 2000 F450 with a 7.3 in it. I am chasing a rough running issue and I have done a bunch of work to it so far. It was running really poorly, like 3 badly limping or non-contributing cylinders, and the rig has not had much maintenance so I did a once over and warmed up the parts cannon. Ran buzz test and cyl's 1 and 3 failed. Ran cylinder contribution test and cylinders 1,3,5 and 8 failed miserably. Changed oil, oil filter and fuel filter. Found a damaged wire going into the right side UVC plug so replaced it with new factory plug, replaced BOTH valve cover gaskets and their subsequent internal harnesses, replaced all the glow plugs while I was in there. I found the bolts on cyl 1 injector solenoid to be pretty loose so tightened them. Ran a buzz test and it failed on cyl3 only now... made noise but sounded whimpy. I replaced that injector and reran the buzz test and it passed with all sounding loud and proud. Put it back together and fired it up and it ran pretty darn smooth. Took it for a 10 mile road test and it had way better power, much better than it has ever had but after about 6 miles, the engine had warmed up and I started to see the service engine light coming on under heavy acceleration after 2000 RPM. By the time I got home, the light would come on as the engine came down to idle again, the power was diminishing and it had an obvious miss. I checked the codes again (cleared them before the drive) and I had an ICP low/high code so changed the ICP sensor since I know that they get screwy and this one looked unhappy. Cleared codes and retested. Same - warms up and starts running poorly and service engine light on and off. I get cylinders 1,3 and 4 throwing contribution codes. I know that cyl 3 has new injector. and heat causes it to act up. So...

My hypothesis is that I either have a high pressure oil leak like injector seals bypassing, an IPR valve problem, or a high pressure pump that is worn out. Being as everything but injector seals is a significantly expensive endeavor (and I would like to retain my marriage - she hates the parts cannon BTW), I figured I take the phone a friend option and see what the zen master 7.3 guys out here had to say. The other issue I have is that I don't know Forescan very well and I don't know how to check DIDM codes. Once the engine warms up and the service light starts turning on and off, I get a code in the PCM for DIDM codes present but have no idea how to get to them.

Thanks in advance for your advice...

 

Going to start with the simple stuff.

When you did the harness, gaskets, sensors, and control items did you get them from the Ford or International counter guy or did you online them? Any part ordered online is 99.999999% likely to be fake, even with the Ford or International name on it. There are maybe five places you can order online and get real OEM. Cramazon, Fleabay, and the corner store are not your friends for this truck. You Must have OEM or the engine will never be happy.

As for the injectors there are maybe two or three places to get rebuilt that will do you right. Where did you get yours?

Contribution tests only ever tell part of the story... #8 will almost always fail or be at least 3% or more than the rest, #3 sometimes the same story.

What are you using to pull codes and run tests?

Have you checked every single connector on the engine harness physically for proper attachment and condition including several inches into the loom?

Have you verified 100% clean, tight, no discoloration, no corrosion or history of corrosion on all battery feeds to include... Posts, grounds (battery, block, frame, fender), alternator connections, starter solenoid, and even the starter?

Are the batteries holding 12.6 volts or better overnight when checked with a proper volt meter?

What codes do you have currently?

Do you have a method to monitor fuel pressure?

Pull your fuel filter and look at the bowl and filter, do not drain it first. What do they look like?

Did you put any type of additives in the fuel or oil? Fuel additives are ok, oil additives cause issues.

More to come after answers.

 

Alright... starting from the top -

I have the extended license for Forescan so that is what I am using for my testing. I was, 10 years ago, a Diamond Certified Navistar tech and was familiar with their software which was WAY more detailed in the data and had more tests available so I feel a little out of my realm software wise. Full disclosure, I was a drivetrain specialist however, so my experience with the 7.3 was limited. Being as I was a factory tech, I bought Ford factory harnesses and valve cover gaskets. The injector is from O'Reilly's - I have purchased a few of them over the years from them and have not had an issue that I can attribute to a rebuilt injector failure. The ICP sensor is new from Dorman. When I did the LOF, I cleaned the battery terminals and inspected cables. The batteries are brand new. and they stay up over night. I have checked chassis and engine ground connections. I have not checked power connections to the starter since those are not active once the engine is running. There are no fuel additives in the fuel and it is low sulfur. There was no junk or water in the bottom of the fuel filter housing when I pulled old filter, prior to any draining of the bowl. I did use terminal cleaner on the harness connectors when I swapped the valve cover gaskets, as well as the main engine harness plug since it had to be disconnected to pull the drivers side valve cover. A basic visual inspection of the engine harness didn't give me any red flags. I have not hooked up a fuel pressure gauge.... I believe it is sitting in a tool box about 300 miles away. Will grab another one this next week and I need to rescan for codes. The water line between my well and house decided it was at life expectancy yesterday so this weekend is going to be something other than a truck repair weekend.

 

Another issue for rough running engines would be air in the fuel. Common cause would be the shower head in the tank is damaged or designated. On that thought are you well over 1/4 tank of fuel?

The ICP being the corner store item would be on the change list also.

Check the CPS also. Pull the wrapping off several inches up and verity wire and connector integrity.

Check EBP, MAP, and BARO to see if there is on odd man out on a cold non running engine. Every one should be near 14.7 psi on a standard day at sea level, your location may vary a bit.

EBP tube and sensor is a common issue with rough running engines. Sometimes cracked tube, clogged at the manifold fitting, maybe the tube itself is clogged, may be a caked up diaphragm. Of the three tubes I have changed on three different trucks over the last few year none were serviceable any longer, after the second one the third I just had my buddy order the sensor and tube to replace.

 

Checked over everything I could with Forescan didn't see anything out of whack. Made sure the EBP tube and sensor was clean (forgot that was a thing, I have been out of the game for a bunch of years now), Tested fuel pressure and it stayed solid at 60PSI under all loads. Ended up having to send it to the dealer and they said the IPR valve wasn't keeping up. Once I got the air entrainment cleaned up from changing the filter, it was only displaying the light at idle and at full throttle around 2200RPM, so that makes sense. I recall being able to verify the IPR command vs actual with Navistar software and just couldn't get it proper with Forescan (probably me). SO the IPR took care of the light issue. Thanks to all that assisted.