Hopefully someone can help. I have a 1999 F250 w/ a 7.3L. Has about 170,000 miles, auto trans. 4x4. A few years back I was having a problem running at lower speeds, say between 1500 and 2000RPM's with the truck jerking and hesitating and feeling like there is a miss or it wasn't firing on all cylinders. I replaced the IPR valve and the ICP sensor at the same time and the problem went away. Fast forward to about a month ago when it started getting below 40 degree's and my truck started acting up again. The problem only occurs between 1500-2000 rpm's. At that rate, the truck will hesitate and jerk and shudder like it had a miss, but once over that speed or under that speed it runs perfectly. The truck idles fine and when I punch the throttle it takes off like a dragster. I have NO mods., everything is stock. No check engine light has ever come on. Once it started getting cold again and stayed cold all day this problem would occur. I plug the truck in every night but it still seems to act up even though the motors kinda warm. My question is........should I go ahead and replace the the ICP sensor again?? I just recently replaced the IPR valve again and that didn't do anything. Is there some kind of sensor on this motor that detects outside air temp. and possibly could cause this problem I'm having? The truck ran great all summer and fall but now that it's cold out I'm having this issue. Any help is much appreciated!

 

Is there a chance this issue could be caused by a faulty TPS, Throttle Position Sensor?? I know it's basically the gas pedal or the switch behind it, does anyone know if those ever go bad?

 

Another possibility is one or more injectors is getting tired. Saw a thread a while back where a guy had similar symtoms, and ran a Cyl Contribution Test, and found one injector bad. Replaced it and his truck ran well again, without the mid range miss.

How old is your CPS?

I wonder if 5W-40 synthetic oil might help you nurse the older injectors along. I'm doing that and notice smoother running.

 

Since a new CPS is only $30 I'm going to try that next. We had a burst of warm air here in Detroit and the truck has been fine. Supposed to get cold so I will see how it runs tomorrow. CPS is going in over the weekend.

 

Just an update if anyone is interested.....after a lot of researching and trying to figure this problem I decided to take a look at the TPS. I pulled it off and sprayed an electronic spray cleaner around the area that rotates. I did this a couple times then turned the center section back and forth. Finally I blew it out with compressed air and reinstalled it. hooked up the wires, fired the truck up, took it for a short ride, and BAAAMMMM, that was the culprit!!!! Runs like a champ! Now I would like to replace just the TPS but can't seem to find it for a 99 without buying the whole throttle assembly, which is $300.00+. I will see how long this lasts.

 

thanks,theres a lot of people waiting for these solutions,to help diagnose there same problems.

 

I've replaced 3 TPS's in my truck in the past couple years. I keep using Doorman & that may be the problem. Motorcraft next time

It's pretty common. Glad you got her fixed on the cheap

 

Frank what kind of issues were you having that you have replaced 3 TPS in your truck? Have you found the part# yet for a Motorcraft tps? Without buying the whole pedal assemble.


Jetskiman I am glad you were able to figure it out and fix it.

 

Ed, The only issue I keep having is a low speed snatchy throttle. I'm guessing in dusty and/or humid environments the TPS gets dirty/corroded.
The few times that I've had issues I was on the road traveling & settled for a quick replacement. Usually I pound on the go pedal with my fist (truck off) The same way Fred Sanford fixed his tv

I've never replaced the complete pedal, just this:

 

Glad you got it fixed and glad you posted the fix so others can maybe benefit from it.