I am sorry if this has been beat to death. I have searched this topic the best that I could. My Excursion (the best suv in the world) runs when it is cold, but when it gets warmed up, it starts to miss like I am missing 2 or more cylendars. It will still run and limp home about 20 mph (luckily it has happened when I was close to home). It has died during these tanturms as well, but it will start after letting it sit for a litte bit, but still missing. When cold, it will clear its throat and run perfectly like nothing wrong.

The Excursion is mostly stock with the addition of a chip and trans command. It still has the stock injectors.

What I have done is to start with the obvious things to me, changed fuel filters, add 911 thinking maybe a jell problem. Lastly, had it at my truck shop and he replaced the fuel pump. No change.

I have a feeling that it is something simple, but I cannot wrap my mind around it.

Thanks for the help and I appreciate the help that has been given by some very knowledgable people on this site as I have studdied this topic.

 

When it starts running rough, are you getting a CEL (check engine light)? If so, you have codes stored. It would be very helpful to know what those codes are. Most code readers cannot help you with a 7.3L so you will need an AE or shop that can do it.

Where are you located? There maybe someone close by that can give you a hand.

Sounds like it could be a loose UVCH (under valve cover harness). Good time to do the 50 cent mod. Do a search on that and you find some good writeups with pics.

One thing that comes to mind is the cam position sensor. Get one from Ford or International (stay away from aftermarket ones) and try it. They are cheap and it's a good idea to have a spare because they are easy to change and can leave you stranded.

Keep us posted on your progress.

 

Thanks for the ideas. I actually get no cel at all which makes me think it being a fuel issue. I'll look up the .50 cent mod. I have never heard of it.

I am in the Seattle area.

Is there a crank position sensor and a cam position sensor? I have had the crank position sensor replaced under recall.

 

The CPS is a cam position sensor.....this is what was replaced during your recall visit. No such thing as a crank position sensor. Hopefully people smarter than I will offer up more ideas. Please let us know what you find the cause is.

 

You can do a flow test of sorts by placing a can under the bowl drain tube, open the fuel bowl drain valve and turn the key on. Fuel should shoot out of the line pretty good. If it does not you may have plugged screens in the tank. Search the Hutch/Harpoon mods for pics of those screens.

 

A bad internal o-ring on the IPR can act just like a bad CPS when the engine gets hot. The oil viscosity gets thin and will bypass the o-ring, You will begin to loose HP oil pressure and the truck can die or have very poor performance.

Just another idea to look at.

 

I'll do the flow test as that seems very simple to do.

What is an IPR? Injection Pump ....

This will be the next thing for me to look at.

Once again, I really appreciate the help and some ideas where to look.

 

IPR = Injector Pressure Regulator - Regulates the high pressure oil delivered to the injectors.

IPR with solenoid



IPR with solenoid removed


IPR in HPOP




IPR Cleaning

 

Payson, this is so much good information. Perfect. I'll do this after I check for fuel flow.

Thank you.

 

subscribing i have the same issue

 

I have learned three things that I will be looking at this week. First, fuel delivery from the pump to ensure that I don't have a plugged in tank filter. Then I will to the .50 under valve cover wire trick. Then I will rebuild the IRP. At each stage, I'll check each one. I wish, like others, that I found all of this information earlier. I paid my heavy truck mechanic to fix this problem and he replaced the fuel pump. Obviously it didn't fix the problem.

 

Keep us posted on your progress.

 

Sounds like a good plan.

You should be able to find a deep socket that will fit the IPR and still accept a ratchett so you will not need to weld a bar to a socket.

 

If after checking all of these things listed above you still find there's a problem, you might consider replacing the engine oil temperature sensor that's on the HPOP. I had an issue with mine when I first bought my truck and replaced it and found it cleared some problems I was having with the engine performance when the engine temp. was up there.

 

Good suggestion Drake. A flaky EOT sensor can cause some weird issues.