Well yesterday I had been cruzin alone for about 550 miles when I encountered a hill that caused my truck to shift out of overdrive and rev to about 3000 plus. I was pulling a trailor at the time and had not encountered and real grades to load the thuck earlier so it was running fine. Any way back to my question, when the truck shifted down and reved up it started missing and bucking like a mule. If I let off the peddal it would shift up and pull fine. When it was bucking the boost was at 26# or so and the egt was at 1400 so I would think it was getting fuel. The truck was also making a little black smoke and it normally does not do that much. I have not changed fuel filters yet or looked at anything for that matter. So do you think this is a fuel filter problem or maby a maf sensor problem or what? I do not have any performace chips on the truck. I stopped and bled the air out of my mega filter but it has never given me a problem before, no change. I then locked out the over drive and rever up the motor and it would miss like a gas engine with an ignition problem. I then went back into overdrive and you could floor it and sometimes it would shift down and sometimes it wouldn't. There were no ses lights or anything. Is there a throttle position switch that would make it not shift down or what?. I let the truck set for a few hours and then went back out and ran the crap out of it and it ran fine. so the million dollar question is what was/is the problem? Any help would be appreciated. Mike-

If your truck is a 2002 and you havent changed your fuel filter yet, then I would do that RIGHT NOW! It could be plugged up and not allowing sufficient fuel to the injectors. If it still does it afer filter change, I would take it in to have it checked out by a dealer or someone who has a tech 2 or similar device to check your injectors. If you havent changed your filter, and dealer diagnoses bad injectors, they could deny warranty coverage because of failure to follow maintenance schedule...which includes changing the fuel filter every 10k if I remember correctly.http://www.dieselplace.com/forum/smileys/Cry.gif

I have changed my filters many times. Today I drained some fuel from the factorty and Mega filters and they were pure clean fuel. I cleaned the maf sensor and put a paper air filter back in the truck. I then took my truck out and ran about 100 miles or so and I could not get the problem to show its ugly head so I guess I will just have to keep driving it untill it messes up again.

How steep of a hill and how much fuel in the tank at the time?

EGT of 1400???? Aluminum MELTS @ 1300, as in Bye Bye Turbo!http://www.dieselplace.com/forum/smileys/Cry.gifhttp://www.dieselplace.com/forum/smileys/Dead.gif

You should see lower EGT`s in 4th at higher rpm then 5th with lower rpm.


1400* is high, but as long as you do not let it stay there for more then 30-40 seconds at a time nothing is going to melt, and even a minute or two probably wouldn't hurt as the coolant keeps the block cool enough to protect it for a good long time. (With that said, I will not be testing it out to see just how long it would last) I have never read where in stock form these trucks getting into the 1400* range.


As trippin mentioned, if you were down around a 1/4 tank and the hill was very steep the truck could have got air in the down shift.


I'd change the fuel filter first then go from there, Process of elimination is the only way to find many problems. If you can get a hold of a Tech-II try using it the next time you tow, maybe it will give you the information you need to correct this problem.

Had plenty of fuel in the tank. I could make it miss any time I would floor it going up or down hills. I would think one would have gotten the service engine soon light the way it ran but nothing showed up. The pyro was burried in the red and it was the highest I have seen it and I have towed thru the rockies many times. I guess I will just have to wait and see if anything further develops. It drives me nuts when my truck does not run correctly and I can't figure out why or get the problem to show up consistantly.

RPM govenor?


When you floor it in neutral, it will feel like it is missing when the RPM's get to about 3350 rpm...Maybe thats what you felt.

I thought about that but when I was running the hell out of it later when it hit the govenor it just kind of got smooth and guiet and did not miss a beat.