Hello long time no post,

Well my truck has developed a pretty nasty "buck" when shifting in and out (particularly out) of overdrive whether it be at highway speed or around town speeds. If I apply enough throttle to cause a downshift in overdrive it will start to shift, the tach will shoot up an extra 700 rpm and then the gear will lock in and the whole truck shudders and then things are relatively normal. My first thought was potential U-Joint or Transmission mount, which both appear fine. next on the checklist is internal transmission problem, or some sort of electronic issue with the shift maps etc. etc, or some kind of low grade misfire as is described elsewhere on this forum, I put in new plugs in January, but didnt replace the coils.

Thanks for any input

Oh yeah, and if I just hit the overdrive off button it shifts relatively smoothly into regular gear, and runs through the other gears fine.

 

hey, did you resolve this? was about to start a thread with the same issue

 

I have a 1999 5.4 with 216k. It has done the same thing maybe 5 times. When it happened it would hit the overdrive button on and off and then it would stop. The shop I talked to did not know what it would be, but said his buddy has something similar happen with an expedition and it had to go to ford to have the computer flashed. I guess you could call ford with that as an option.

 

woah this is happening to my 1997 f150 5.4 4x4 same thing rough shifting when high rpms i think mine is into third and 4th(overdrive) tho.

 

A similar issue has lead me to think that I have coil problems. In general the behavior sounds the same as mine. A few questions, do you notice that when the air temp is lower, the problem isn't as bad? Ever get a Flashing CEL? Do you notice the bucking (even ever so slightly) when the truck is running at higher RPMs?

I initially thought it was an Overdrive problem but as air temp went up on my drive to Chicago, the problem became wven when OD was off.

I have coils on order. I will update when they come in and I have them on the truck (along with plugs...)

 

Issue is still going on, although I am not currently using my truck (at the beach with another vehicle) I would say that air temperature does seem to be a factor, I am in North Carolina and on the 80+ degree F days it seems to be noticeably worse. I have never had the CEL come on, but if you have a flashing CEL that probably indicates a miss in the engine so most likely is a coil or plug foul. My issue is happening pretty consistently so I do believe it is more of a transmission problem than an engine buck, I am holding out hop it may be some sort of computer bug (I've been looking for an excuse to get a chip anyway). I should note that my issue occurs across the RPM range whether I am going 70 on the highway or 45 in town, anytime it is in OD and I give it enough juice to downshift it bucks. It just happens to be more violent (kinda sounds like the transmission is coming through the floor panel to eat my soul) at higher RPMs/Speeds. There seems to be a lot of talk of issues like this, however there also seems to be several causes.