07 PSD, bucks/jerks before downshift at highway speeds
 

All,

I am trying to figure out an issue with my 2007 6.0 PSD. When I am at highway speeds (60 ~75 mph) and I approach a hill, my truck starts to buck / jerk a few times before it downshifts. If I give it more gas, the downshift is smooth. There is plenty of power, its not 'missing'.. if just feels like it can't make up its mind to down shift. I am NOT hauling or towing anything at the time this occurs.

Here are some of the things I have down to attempt to diagnose:

* No Codes in my scanguage II
* Pulled the EGR connection and drove the truck, problem still occurred.
* Noticed that when the transmission temp is above 150 degrees, the problem does not occur as often.
* initially suspected injectors, ran some diesel clean thru

Some of the things it does right:

* Pulls nice and strong when you get on it.
* No bucking/ jerking on downshift when below highway speeds.
* Normal shifts around town are smooth and event free
* No issues changing from reverse to park to drive.

I've tried searching and can not find anything related to my issue. Any ideas?

Thanks in advance!

Moved to the 6.0L Powerstroke Diesel forum.

Thank you!

you may have a lock up torque convertor issue i would try to have codes read by a scan tool that can read all powertrain codes have you tried tow haul mode just food for thought

There are a couple of things you can check. Pull the EGR valve and clean it up if it's dirty. Also, check the small black rubber hose from the passenger side intake manifold to the MAP sensor and the nipple it connects to on the manifold for an obstruction, it could be stopped up. And check the EBP tube and sensor for crud. It's a hardline on the drivers side front of engine. Good luck! Could be a no-cost fix.

I had a very very simliar issues as to the one described here as well. I was concerned it was a tranny related issue as well. Well Had it in the shop today to run some tests and they came back with "Found Turbo assembly sticking causing lack of boost". It sure didn't seem like a lack of boost thats for sure. Wanted to replace the turbo and VGT solenoid. $3600.. WOW.

Wow.. that is no fun. I monitor my boost at the time this is occurring, and there are no spikes or drops in boost. so I hope that is not the case here. This weekend I am going to pull the EGR and clean it if needed. figured I'd start there.

Were you monitoring your stock boost guage? Cause I looked down in that direction as well and it said it had a bunch of boost and I didn't see it move as well. I think I am going to pull the EGR as well this weekend to see what shape its in. Keep us updated on what you find. I am going to be pulling my trailer(10K) here again in a couple weeks and will see what happens. As well take it on the highway and without the trailer and see if I can make it do it again. Going to run some ctane boost and cleaner as well for a few tanks of fuel.

No.... stock guages in this truck are mostly useless. I am monitoring boost via my scangauge II

I've been running Diesel Clean in the last few tanks too.

I find the less I am on the gas pedal as I approach a hill, the more it is bucking. If I feed it a bit more pedal, it seems to make up its mind. down shift, and go :D

Bucking sounds like a injector has gone out. Or is on its way out.

From what I read, that is not a hard fix, but what stumps me, is this truck pulls just as hard, if not a little harder than my buddies. All gears / speeds it does not hiccup a bit.. but.. once I am at highway speeds relaxed or on cruise control, and approach a hill it bucks a bit before downshifting, and once past the hill, is OK.

If It were an injector going, I would assume that it would be an issue in all gears?

I would make sure the strategies are the most up-to-date before starting to replace things.

Will do. I'm going to make an appointment at ford to just have them check and update the flash on the CPU's

Took it to my buddy at ford, and check the software revs on bothe the ECU and TCM, and both are up to date. The mystery continues.

He did suggest that we drop the pan on the trans, and replace both filters. (i did not know there were two.) Seems like a reasonable thing to do, and it wont cost me too much money or time.

Any other suggestions?

Also, forgot to post that I removed, cleaned and inspected the EGR. It looked OK when I took it out. not all coked up.

http://i266.photobucket.com/albums/i.../dirty_EGR.jpg

cleaned and just before installing seals back in

http://i266.photobucket.com/albums/i.../clean_EGR.jpg