Clearly this has been discussed before and probably posted in the wrong location but yet again I have not found an answer to my problem in any other posts. 95 F250 7.3PSD E4OD. It shifts really firm 1-2nd, coin rattling/drink spilling into third, and real firm into 4th or OD. Problem occurred when I first bought the truck for cheap, bought a tuner with trans tuning hoping it was a messed up shift strategy because I am getting no codes or flashing OD light at all at any point and all electrical connections are good and checked several times. So when my problem didn't go away I installed a transgo shift kit with recalibration plate and noticed there was already aftermarket springs in the accumulator valve body but no calibration plate but looked to be trango's spring orientation. So I installed new springs and the plate and bam everything was perfect, the truck ran phenomenally and shifted like it was new off the lot with just a touch of extra kick in each gear, and I mean just a touch no further. Drove the truck for a month and then it sat for 2 weeks while I did a little at home project of giving it a flat bed to get rid of a terribly rusty bed. After that two weeks and listening to the radio of the truck while it was not running, I started the truck, no dead batterys no long crank and nothing to worry about. I get in to test drive the truck with the new bed and its shifting like crap again. Only modifications done electrically were new taillights, jeep style to match the flatbed hay hauler look. Wired up properly and no fast flashing and of the lights but probably added about 2-3 inch of extended wiring to the harness. I tried reseting the pcm and running every setting in the tuner including stock and no change except when in the "hot tune" it shifts smooth but again I don't run that tune hardly at all so I'd like my 80hp daily tune and others alike to shift like it did 2 weeks ago. Any suggestions on what it could be? Filter and fluid changed, solenoid back cleaned at the connections, speedo jumps a little around 70ish mph but not noticeable at slower speeds. Could it be the taillights? Could the accumulator pistons have gotten gummed up while sitting? Or is there a problem somewhere else that is being over looked? Again no codes or lights other than low map sensor input but it has had that before and after this problem reaccured.

 

LED taillights?

 

Not LED taillights, standard filliment bulb.

 

What did you do with the third brake light?

 

The 3rd brake light was left untouched and still works with the standard bulb

 

That means the problem never went away, the only other thing that could cause this a bad PSOM. Is your speedo needle bouncing?

 

The needle bounces around 70+mph and its quite a bit when it does but 70mph and under it is steady with maybe slight movement over decent size bumps. I don't know how to tell if a PSOM is bad tho, it did recalibrate when I went in and set the right tire and rear end ratio because it was 3ish mph off when I bought it but had the smaller of the two stock size tire setups

 

I read into the PSOM on a couple other forums also and this seems like it could be the culprit, its the last thing I haven't tried and haven't really thought of, ill start by checking the connections and seeing if its a loose plug tomorrow but after that If it doesn't get better then a new PSOM could be in order considering the VSS is new and the wiring is good, both new and old VSS acted the same way for the most part so it could be a loose connection on the PSOM that I've read, if not then replacement or ill just let the transmission shift hard until it blows and then rebuild. Not looking forward to it but it is a high mileage truck so about time I guess lol.

 

Checked connections and replaced PSOM from a truck built in 03/95 and mine is from 07/95. It went in just fine, got the gear and tire size set in for it and same issues although when the truck is cold and the trans is cold and I go to drive it shifts softer to a point thats easily manageable, but as soon as it gets a little warmer, about 5 miles down the road, the symptoms start back up again.

 

For anyone that finds this comment on this thread, problem was solved. The barometric pressure sensor was not reading right. I took the cap off the sensor that blocks in the circuit board to unveil a gel like coating all the way around the circuit board, it was clear and the board looked to be fine, while that cap was off the barometric pressure sensor it read correctly, no noticeable engine performance difference but the transmission did not have a single hard shift. I ended up drilling a few holes in the plastic cap to let more air pass through into the sensor for a "clearer" reading and it has been working for a week as well as the MAP sensor code going away with this "fix". New sensor on the way to prevent this one from causing anymore problems as a sensor like this should not need to be modified to work. But as a quick fix and a suggestion for anyone with similar symptoms I'd give it a try and see what happens, after all it was free.

 

Nice good to know and congrats on the fix

 

Nice find! Post back when you get more miles on her.