I bought my '94 F150 XL 4.9l in early February with around 248k miles on it and it drove great. The next day, I drove maybe an hour away, and on the way back home it started shifting extremely hard when going into 3rd gear. So I dropped the pan, replaced the filter and the fluid that was lost, which already seemed pretty clean, and that didn't seem to fix it. The problem I was having was that once the truck got up to operating temp, mostly if I spent a lot of time in stop and go traffic, it would occasionally shift extremely hard as if I was getting rear ended into 3rd or 4th gear. I was not having any speedometer issues, the overdrive light never flashes when I shift, and I don't have any dash lights.

I first replaced the VSS in the rear diff with a napa sensor, which made the speedometer jump around after 15-20 minutes of driving, so I just recently put the OEM one back in and it works fine. I put a new motorcraft TPS, which seemed to help a little bit. Then I replaced the MAP sensor, which only made it shift a little less hard.

The issue is still around, but way more inconsistent, it'll shift late and hard at any given time, going into any gear, but it's totally random, again mostly if I'm stopping and going for a little bit. And sometimes when shifting it feels like it slips into the next gear right after and it has low power unless I floor it. I've attempted to pull codes twice now and I only get 512 which leads me to believe it may be a PCM issue. I'm almost at a complete loss with this truck, and I'm hoping it's not an internal transmission issue because sometimes it drives perfectly fine, then randomly it gives me issues. This is the first automatic I've driven for more than a few weeks, and it's done nothing but stress me out lol.

 

My 94 , 4.9 E40D does similar occasional hard shifts, and a few weeks ago, it slipped for a few seconds. i took it to a trans shop , they couldn't replicate the symptoms , drove it every day , four days in a row. They cleaned up all the electrical connections and I brought it home trouble free. I haven;t had a chance to drive it again since but plan to go to a cruise night about a 35 mile drive from home on Sunday , so hoping for the best. The trans man [ ] wants me to bring it back when it does it more consistently.

 

My '95 F150 does similar. It bangs the 1-2 shift when the trans is cold but when fully warmed up, the problem goes away. I'm getting code 452 for the VSS but the speedo and cruise work perfectly.

 

Mine does / or did, the same with an E4OD in a 94 van with a 5.8
I sure would start with a 1994 PCED and at least look at the pinpoint test steps for code 512
I happen to have a 94 pced and can post the start of some of that if you want
I also replaced my processor recently for a drivability issue (missing)
Now my trans shifts smooth and only shifts hard once in a while, depending on how I am driving it

 

In my book, 452 is a VSS code, but 512 is not. Im getting 452.

 

I think it might just be an E4OD thing. Mine shifts hard from 1st to 2nd almost every time and it always has. It can be a bit annoying but it's an old truck with almost 150k miles so I'd almost expect to have little quirks like that. They say unplug the RABS but it doesn't bother me and hasn't broke anything yet.

 

Mine will shift hard, usually first to second, but when I come to a stop, throw it in park, then back, and smooth sailing after that. If I remember, before the hard shifts, I'll do that. Not sure what it does, but works every time

 

I did the trip to the cruise night, had one episode of hard shifts then was ok to the show. On the way home at 90 kmh [ 55 mph] it suddenly revved way up like it went into neutral, I let off the gas, it had a hard downshift, then was ok the rest of the way home. I haven't driven it since. I called the trans shop, the guy I talked to said a 94 E4OD does not have alot of electrical components, and he suspects a valve body or something of that ilk. I guess I will just have to park it for awhile, I don't have the funds to do anything with it for the time being.

 

Find a different shop that knows what they are talking about. There is a solenoid pack and shifter position (MLPS) sensor on the driver side. The transmission is 100% computer controlled. Your symptom is quite often caused by a failing MLPS sensor...that typically does not trigger a code.

 

That is exactly what I was going to say.

 

Yes, the E4OD does have fair amount of electronics, but compared to today's newest transmissions, they don't have a lot of electronics. Matter of fact, everything 30 years ago were not very sophisticated compared to today's stuff.

 

Thanks for the replies, I guess is they likely don't want to get involved with it. Once I have some $ I can put towards it, I will go to a shop that all the shops I deliver parts to in the area recommend. I now work at a Napa location, I will ask the counter people to find me a MLPS sensor and go from there. I'm assuming the sensor is 94 specific ?

 

Yeah, I cleared the code and drove it, it drove good for roughly 10 minutes before shifting super hard again so I scanned the codes and got 512 again. Pulled the PCM out, didn't take it apart but the pins and casing looked pretty old and rusty. I ordered a new one from flagship one that should be arriving in a couple days which will hopefully fix my issue, or atleast allow me to diagnose the issue further.

 

Changed out the speed sensor in the rear-end with another one I had on hand and it fixed my problem.

 

How did you clear the Stored Codes?