Recently bought a 1994 Ford F250 XLT RWD 7.5 L 460

83,000 Miles Original

Recently has started to randomly shift Chunky between 1st and 2nd
and Chunks from P to D and P to R

If i unplug the battery and reset the memory, it shifts good for a couple days then goes back to the random chunks

bought a code reader and it spit out Code 628

Torque Slippage

does not look like Transmission Pan has ever come off this thing. Fluid smells slightly burnt, but not overly

Should i start with a full transmission fluid flush?

Or think its Torque Convertor?

Or simply a sensor?

if anyone has had this happen to their Truck…

looking for suggestions before i start with the Flush!

thank you so much

 

 

Im dealing with the same issue on my ‘96 f250 with the 460. I’ve replaced a bunch of sensors and checked a bunch of different things but I’m still pretty lost.

 

Ford spent a lot of money giving us codes to help us figure out things. If it has 628, my guess is that the converter is slipping.

Although the miles are low, they could be all towing miles. Miles is really the only thing we got to determine how worn the truck is, but it's really a poor way to judge a vehicle.

When the EEC-IV 'sees' the converter slipping, it will go into a limp home mode. Basically it gets full line pressure which makes all the shifts firm. I eventually purchased a temperature/pressure gauge for my E4OD and I know before I feel it that I am in limp home mode. If you think a temp gauge is a good idea, spend a few dollars more for the temp/pressure gauge. It's worth it.

My guess is the converter is toast. There are some plastic valves for the converter operation that can distort with heat. If your fluid smells burnt, as far as I am concerned, the damage is done and new fluid is not going to help. If you choose to go down that road, my stock converter had a drain plug. I suggest you spend the time to see if yours does too. Best to drain all the fluid, not just the stuff in the pan.

I built a strong E4OD and with the modifications I did, I took my trans out several times. Originally, I put in a billet 3 clutch converter and I got a 628 code. I ended up getting another one rebuilt and eventually a third. I think I got it dialed in. One of the things I did [and I did a lot] was to change the coding of the EEC-IV to NOT test for converter slippage. Another thing you can do is drill the orifice slightly larger for a firmer lock up.

My understanding is that Ford had a tough time with that code and how to program it to work properly. Mark K is the person that can elaborate on that.

 

That code is pretty reliable. When the trans is in fourth gear, and the converter is commanded to be locked, it calculates from vehicle speed back to engine speed. If the engine speed is more than 50 RPM higher than the calculated value, code 628 i set.

Those years E4OD had a torque converter problem. The converter clutch apply piston often developed a crack. This allows apply pressure to bleed off, and the clutch slips, and code 628 sets. I thihn you need a new torque converter.

 

yes. Trust the code. Its more than likely the Torque Convertor. Its what fixed my issue with code 628 in my 94 Ford F250

Id also suggest putting a new Neutral Switch Relay on while theyre down there

the biggest expense is dropping the transmission to GET to the Torque Convertor.

good luck. I know its a crappy feeling.