Hi all....new to this forum and hope someone can shed some light on a problem I have been having with my truck. It's a 2002 F350 CC 4x4 w/7.3 PS. The trucks starts fine and runs fine for the first 5-10 minutes, then at around 40-50 MPH when driving at a constant speed, it starts running rough, jerking, bucking, etc. If I step down on the peddle it accelerates fine with none of this hesitation. This occurs for about 5-10 minutes, then it goes away and runs fine the rest of the trip. Also, this only happens when the temp is below 40 degrees. It was doing this last winter, then ran great over the summer, and reappeared again this winter. Any ideas??? Thnx in advance.

 

Did you do the cps recall? I read alot that the cps can do crazy things.

 

Its the EBPV ( exhast back pressure valve) Its closes to help warm up the motor when its cold and if your not on the gas when driving it will come on till you thottle up then it opens again. Its normal.

 

Im not so sure the bucking, jerking, and running rough is normal. My EBPV makes the truck sound like a jet engine, but my motor still idles just as smooth as ever.

 

I didn't get a recall notice on the CPS, but it has a new one in it. The EBPV functions fine at idle. This is a new occurance. Definitely was not this way when the truck was new.

 

OK yeah thats true. U think it could be a fuel issue also? The CEL 'could' come on with the cps going out if it was runing like discribed. A scan tool would tell you more also.

 

I just got my recall but don't know if I will take it in yet. When did you change the oil last and fuel filter?

 

It's not a fuel or oil problem, I don't believe. Everything has been changed recently. It just seems like it occurs as the engine is coming up to temp, then goes away when everything is completely warmed up. Diesel is too expensive to let it sit in the yard for a half hour warming up before driving. Might have to try it though just to see if the problem still presents itself.

 

I'm thinking maybe its an injector issue..like he has one that's not priming correctly. If its bucking and running like crap, almost like he's running on 7 cylinders...it might explain why it gets better when it warms up.

It sounds too severe to be a cold start rolling idle issue. ..especially since he says it only does it at 40-50 MPH and only if its not up to operating temp.

Maybe a CPS issue? If you're due for a new one from the recall, you might try changing it out and see if it cures the problem.

 

The cps is on the list of things to check but probably not going to be it. Put the old one or your spare on. Also, check the EBP and EOT sensor for biased readings. Make sure the EBP tube is clean but it sounds more like a biased sensor or sticking valve as it only happens at that particular time and temp only. Good luck.

 

I have a 99 F-350 and its doing the exact same thing. I just changed out the cps so thats not it... Only does it at temps below 40, once the engine warms, or when you accelerate, it does fine. I've been trying to figure this thing out all winter??

 

I know I should just bite the bullet and go get it looked at, but summer is coming and all will be fine. Quite irritating when it's cold though.

 

It's still something you should figure out. It may point to an even bigger problem.

 

Well, I finally bit the bullet and had a diagnostic scan done($95). There was a Throttle Position Sensor error code that came up. The tech took a ride with me while hooked up to the truck and there was quite a fluctuation in voltage from the TPS with the peddle at a fixed position so it looks like that is probably the culprit. I just placed an order for one. Should know for sure in about a week. Another check I did was to activate the cruise control when it was acting up, and the problem went away.