I have a 1993 F350 Crewcab 460 E4OD FWD. I don't post much here so please be nice. The trans has about 40K on it since a rebuild.

When it's cold or up to about 170 degrees the overdrive shifts properly with a nice firm shift and no slippage. The 1-2 and 2-3 shifts are also very firm. If it gets much above 170 then the 3-4 shift doesn't happen. After the 2-3 shift the TC locks up normally and also no slippage. When it's shifting properly, pressing the OD button puts it back into 3rd and pressing again it shifts into OD. Above 170 degrees the OD button turns on/off but has no effect.

I'm using Redline D4 synthetic ATF, but I've tried almost every other brand too. This started intermittently about a year ago, then worked just fine for about 8 months, now its acting up again.

My truck has a trans temp gauge with the sender in the pan. I know it's accurate and I've checked it with an external thermometer.

There are no codes other than 11 (OK) and no MIL and no flashing OD. I've changed the solenoid pack, replaced the accumulator valves (Sonnax kits), tried different brands of ATF. I've also replaced the TPS and MLPS and reset the PCM. The ATF is clean and not burned. The transmission never gets over 190 or so even on a hot day under load.

I have searched all over and can't find anything related to this problem. Has anyone heard of a E4OD with a temperture sensitive 3-4 shift (or non-shift) or know the cause of it? I can't think of anything else to check other than to pull the transmission out and go thru it.

Thanks!

 

That is a dandy problem you have there. I do not know much about the internals of these transmissions, so I cannot help you.

 

It would be nice to know what the two shift wires are doing when it is to shift to OD (4th).
They should both have 12 volts on them (not grounded). I have my shift wires wired to the cluster so I know what the computer is telling it to do at all times.

If both shift wires are hot and the transmission is not in 4th then I would think that something in the transmission is sticking as it expands and its tolerance is too close in the first place.
Either the Overdrive Clutch Assembly, Overdrive accumulator regulator valve and spring or the 3-4 shift valve and spring - damaged, stuck, misassembled.

Also I thought that a 1993 with a E4OD should have three digit codes so you should get a 111 and not a 11.

 

Thank you subford. I guess in all my poking around I don't know about the shift wires. Which ones are those? I'm guessing that's the connector on the solenoid pack? I could never find a documented way to bench test the pack without replacing it.

BTW, I'm not running the stock strategy in my PCM, I'm using the ICY1 that was used in the Lightning, which may have something to do with which codes I get. The engine in this truck doesn't run well with the factory programming.

If you can let me know about those wires and I'll get that checked today. Thanks!

 

This might help with the wire colors:

Courtesy of FordFuelInjection.com

Bill has that pic posted as well as some other info in this thread: https://www.ford-trucks.com/forums/9...direction.html

 

Thanks for the diagram and link rla2005. For some reason I forgot about fordfuelinjection.com.

I'll digest this as soon as I get a little work done at my real job.

 

I was talking to a friend, who used to be a Ford tech about 20 years ago, about this problem today. He recommended adding half a quart of mineral spirits, and while the trans is cold and shifting properly drive down the freeway pressing the OD button on and off. He said that it sounded like a valve that had varnish on it, and perhaps the movement of it with a little added solvent would free it up.

So after work I put in half a quart of solvent and spent about 30 minutes driving at 60 or so going in and out of OD. And gee whiz, it seems to have kind of solved it. After it warmed up it continued to shift in and out of OD, although not as crisp as when it was cold.

I didn't get a chance to look at the wiring yet and if this is resolved I'll put that on that back burner. I'll spend some time tomorrow doing the same therapy and I'll post if it's fixed or not then.

Thank you to those that responded.

 

Would it be wise to say it may be related to a bad ect? I believe the torque converter shouldn't lock until the engine gets to a certain temp.

 

But the problem statement is related to no 4th gear, not torque converter lockup. Otherwise I would agree a bad ECT could be a contributor.

 

This morning I spent another 30 minutes driving down the freeway pressing the OD button on and off. The trans only got to 170 or so and everything functioned normally.

Then later this afternoon I drove to the airport to pick up my wife and the temp went to about 180 after about a 60 minute drive. OD worked when it was supposed to but was a little soft on the shift -- no slippage however.

I thinking it's a stuck valve related thing, although I don't know enough about auto transmissions to know which one it could be. The 3-4 accumulator valve is new and not sticky, and I polished all the accumulators before reinserting them in their bores. I never removed the main valve body so maybe it's something in there?

I also think a combination of synthetic ATF, the added solvent, and working the OD in and out when it's cold has freed something up -- I just don't know what. So I think I'm making some progress.