I have a 1995 F-350 with the 460 and E4OD, has 134k miles on it. Owned it for a couple months, transmission has always shifted normally. Last night I was driving home and about halfway through the trip, the transmission started shifting hard. The lighter I was on the throttle, the harder it would shift. No CE or flashing OD light. I drove it this morning thinking maybe it would reset overnight but it seems to still be doing it. Going to check the fluid today but not sure if this is something I should be concerned about, it’s still completely drivable it just jolts a little bit when it shifts.

 

Probably codes and the transmission is in some type of limp home mode. I would check for codes. The OD light does not always flash if there is a code.

 

To check for codes, do I just run the two regular tests through the EEC or is there a separate one for the transmission?

 

The engine computer also operates the transmission.

 

Ran both the KOEO and KOER tests, KOEO came up with a code for excessive converter clutch slippage. I reset the codes and the truck started shifting fine again, not really sure what caused it.

 

I willing to guess that the torque converter is slipping, causing the EEC-IV to put the transmission in limp home.

If you do some research, you will find all kinds of issues with that code and all kinds of ways to fix it. Considering that your truck is pushing 30 years old, don't be surprised if the converter is no good.

 

My 94 was doing the same thing and I was expecting a trans rebuild. After some research I decided to try some Seafoam trans cleaner to unstick things and mine shifts perficly ever since. You might try it.Put it in, run it 100 miles and do a fluid change.

 

I've experienced hard shifting in a few trucks that ended up being the throttle position sensor, and it was like you said, light throttle shifted the hardest. It felt like I was getting rear-ended every time it shifted

 

Curious, do you add the Seafoam to the existing ATF? I'm more interested in doing it just to keep things free, as a good maintenance.

 

Add the Seafoam to your existing fluid (following the insrtructions onthe can), the manufacturer says to drive the vehicle 100 miles then do a fluid change. I'm not sure if leaving it in longer or permantly would have any negative effects. I would suggest contacting them with that question.

 

I'm gonna try it. I've used Seafoam on a diesel forklift, it actually freed up whatever was causing it to tick.

 

Yeah, It's worth a try. It worked for me and I was amazed, I was ready to tear into my trans and replace the solenoid pack and then start checking from there if that didn't fix it. I boufght the Seafoam I used in my truck on Amazon , it came from a seller in Texas. Later I decided to do the same treatment on another vehicle just as prventative maintenance so I bought a can at my local parts store, it was completely different .I'm in CA and the smell was much different, even the can looked different no petroleum distillate smell. The CA stuff seemed tamer. Is it just as good? I don't know.

 

You must somehow be reading my mind. I am unfortunately in CA also. I was pondering, "self, I wonder if I can even get Seafoam anymore???". We can barely buy spray cans anymore, although Seafoam is liquid, I hadn't thought about them changing the formula...

Oddly, all counties in CA aren't all bad. I am currently building a home/shop to retire to in Lake County, and you are only required to smog vehicles when you purchase them, and it's a law that the seller needs to provide a smog if they sell it. I got a P.O. box and registered all my vehicles that required smog to Lake County, no smog required if you own the vehicle already. But as far as products like paint and toxic liquids, I think all of CA is the same now.

We gotta get rid of Captain Hairdo, this state is really going down the toilet.

I like your username, I sold vintage guitars for a number of years and used to have a store in Hollywood. At that time I used to have a '67 Mustang GTA convertible, it had a high performance 390 in it. I had to sell it to pull my house out of foreclosure upon moving back stateside from Japan. I hate to say I sold the car to a guy that sold me guitar cases for only $6500 in 1987. Damn, I wish I had that car now.

EDIT: and just to be clear, my E4OD has a rough shift when the flatbed is unloaded. When I have a load on it, it seems to shift easier, and this was why I was considering using the Seafoam. Once up to speed and in OD it runs fine.

 

Ive used seafoam trans tune in my e4OD and my power steering with great results. I used a good amount pre-fluid swap where i drained the converter and the pan. so almost 13qts for a 2wd(less fluid than a 4wd with a deeper pan)

IIRC, accumulators on the e4od are a relatively common thing needing to be serviced, heres a link
https://www.sonnax.com/parts/2109-1-...trol-valve-kit