Tow Vehicle Over Revving Problem


#1

Ok, so this isn’t exactly an E30 question but it is related in that it’s a question about the vehicle I’ll use to haul my E30. It’s a new to me 1999 Ford F250 XLT V10 Super Duty 4x4. On a recent road-trip from Pennsylvania to Georgia to pick up my new 24’ trailer I experienced an odd over revving problem: After traveling at highway speeds (70-75 MPH, 2k to 2.5k RPM) for several hours and then traveling approximately 50 miles at slower speeds: 40-50 mph, the truck would not idle below 2.5k RPM. At each stop light I had to stand on the brakes (or shift into neutral) to keep it from creeping forward through the light. After finally reaching our hotel, turning the truck off and letting it sit for approximately 30 minutes – it started right up an idled normally at .75-1k RPM.
I drove around at “around town speeds” all the next morning before picking up my trailer and drove at highway speeds all that day before stopping for the night in Virginia with no problems. Started off again the next morning at highway speeds, stopping for rest stops and gas with no problems. The last leg of the trip was similar to the first day in that there were several hours of highway speeds followed by approximately 50 miles at slower speeds and again, the truck would not idle below 2k at lights.
Has anyone ever experienced this? Any ideas what might be going on?

Bob


#2

I don’t know if it’s typical for the V10, but the first thing I’d check on a Ford would be the throttle position sensor. It’s basically a potentiometer and with a meter and the specs (that I don’t have, sorry) you can check it’s function. Fords are pretty well known for those to fail.

No check engine codes?

I had a similar fast idle problem on my ancient Ranger that was a solenoid for the throttle body IIRC. Don’t know if yours has anything similar.


#3

It’s not the TPS. Swapped it out last night with a new one and still the same. I’m not getting a check engine light and I don’t see / can’t find a vacuum leak. The PCM seems to be the next logical place to look so it looks like it’s off to Ford Service.
Thanks for the help.
Bob