My 1999 F250 SD 7.3l has developed a severe surging problem. When the surge occurs, it completely takes over the engine, surging between about 600 – 700 rpm (as close as I can read the dash tach). Flooring the accelerator will not increase the rpms, and the vehicle has practically zero power. It won't move fast enough for the speedometer to show anything. The problem is intermittent, and at first seemed random. But there is a pattern, which I discovered after doing these things:

1. Replaced dirty air filter with K&N

Replaced fuel filter
A friend brought his big scanner, and it showed a bad EPM sensor.
a. removed the sensor and tube to clean them, and discovered a hole in the tube.
b. replaced the EPM sensor and the tube with new from Ford..
c. The engine still surged
d. disconnected the EPMV actuator rod, and opened the flapper.
e. The engine still surged.
The pattern seems to be that if I crank it when engine is cold, like having sat all night, it starts and idles fine for about 15 minutes, then it starts the surging. After it idles for 30 or 40 minutes it smooths out and can be driven normally all day long. If it is shut down for more than about 45 – 60 minutes (not exact) it will surge when started, and then you're stuck until the tantrum ends.
No CEL is set.
Have any of you been through this?


Thanks,
Sam

 

how many miles do you have on the crankcase oil ?

 

Almost 6000 miles. The truck has 183000.

 

Suggest you change your oil... consider using Shell Rotella Syn.. 5w40..(available at Walmart) Your High Pressure Oil Pump, (HPOP) which controls your injectors, likes clean oil, especially on cold starts... If you are having what sounds like the famous "romp, romp".. using synthetic oil will fix it..

And Welcome to the Forum...

 

You may also have a bad ICP sensor.It sounds a bunch like mine was when it was going bad
You can try unplugging it and see if it starts normal

 

Good thought..
In case you can't find the ICP... see post #9 of:
https://www.ford-trucks.com/forums/9...-starting.html

 

I think the ICP is going to do it. I waited until I could catch it doing the surge, then shut it down and removed the ICP connector, The connector was full of dirty oil, but the harness looks clean and dry. Cranked it up and it ran ok. Located the part at the dealership in the next town, we'll pick it up and install it first thing in the morning, then I've got errands and chores to run all the rest of the day, so we'll check it out.
Many thanks to you all for the inputs.