Looking for a bit of wisdom from this awesome group of mechanics.

I have a 1995 F350 7.3 4x4 with E4OD stage 1.5 injectors from full force diesel.

The current issue I am struggling with is a transmission issue.

Issue:

The truck shifts like a dream for the first 5 or so miles until the transmission is fully up to temp. Once up to temp it can be cruising along at 60 mph in OD with the Torque Converter locked up (I have a lock up switch installed as well. Did this as a part of my testing to determine if the issue is electrical or mechanical) The truck feels like it is not delivering power to wheels, the RPMS spike up to 3-3.5K rpms. I have hooked up a FORScan Lite and can see the torque drop from 200+ nm to 70-80 nm when this happens.

After this happens if I come up to a stop light, I give it very little throttle and hopefully get back up to 45 mph. If I give it to much I see the rpms climb with no noticeable difference the acceleration.

This seems to start at the top of 2nd then carries on through 3rd and 4th gear.

Back story:

This truck has been a long-term project for me and had a bad transmission when I go it. So, I bought a parts truck with a transmission that had 30k miles on it a couple years ago. As a part of this I took the existing triple disc torque converter to a local shop that builds pulling truck transmissions to be rebuilt. Once I had it all the parts ready to go I took the truck to a local shop to swap the transmissions. Once I got it back I put a few miles on it (less than 100 miles all short runs). Turns out the PCM had issues (replaced it) as well 3 of the injectors needed replaced (thus the full set of stage 1.5’s from FF). Once I resolved both of those issues and the engine was running great I could actually drive it in an attempt to shake down what is next. That is when I run into the transmission issue above. Sure enough first thing I check is the trans fluid and it is 4-5 quarts low. Now there is no leak so this is from the shop that swapped the transmissions for me.

Due to the low fluid I am suspecting this messed up the torque converter but I am coming to this group for a bit advice.

BTW just put in a new solenoid pack with no change in behavior.

 

Are there any codes stored?

I can't see how low fluid could mess up the torque converter. I CAN see how it could mess up the clutches in the transmission. What did you see in the pan when you changed the solenoids?

 

Sorry, I knew I should have pulled the codes prior to posting this. I will work on getting them.
BTW, standard code reader or FORScan Lite does not pull the codes for me. I find I always need to hook up AutoEnginuity on a laptop to pull them. Not sure if I am doing something wrong.

Actually, just a bit of gray dust (obviously wet) like accumulation around the magnet. Nothing else. No metal pieces in the pan.

 

Unfortunately, no codes. I used but AutoEnginuity and FORScan Lite to see if it would return any codes and both came up blank.

The OD light is however still flashing - I would assume that means either the transmission is in limp mode or there are codes and I don't know the right way to get them.

Found this link so going to look at performing this next. https://www.ford-trucks.com/forums/1...e-96-f350.html

 

Sorry for the delay in response. I am sure you all can empathize life tends to shift project priorities.

So I looked under the hood for the diagnostic port. I was expecting it to be by the fuse box but no luck in locating it.



Quick update on my testing. So I wanted to see if this was OD related or if the same would happen in all gears. So, I turned the OD off which should only make gear 1-3 available. As always for the initial 5 or so mile of driving around up to about 45-50 mph I had no issues. My assumption is once the transmission is warm is when this occurs. Once warm again it seemed like this same issue above is happening in at least gears 2 & 3. These trucks shift out of 1st so fast I couldn't tell if it was happened in 1st.



At this point I am guessing I need a rebuild of the transmission as some of the clutches are fried. That being said I don't know enough about transmission to be certainly this is actually the case. Would a transmission only slip when warm and work flawlessly when cool?

 

I'm guessing that the MLPS (Manual Lever Position Sensor) is failing. As it starts to go bad it reports to the PCM that you've shifted to neutral, so the PCM shifts the trans to first gear, which at speed, feels like neutral.

Install a new MLPS. It is the sensor on the driver's side of the trans with the wiring harness.

 

Mark,

I will get right on this. That being said I believe you may have hit the nail on the head. On the bottom of my list of items to fix on the truck was research why the reverse lights stopped working.

 

Could this possibly be a valve in the valve body sticking?

 

Well, I have the new MLPS installed. Unfortunately, while installing it the shift cable bound up so off to get a new one of those. Hopefully, test driving it tomorrow.

 

No. No valve in the valve body can cause this.