I've done plenty of searching, but haven't found my exact problem on the site.

It appears that my 94 E40D (I6) has no problems at all when the weather is cool, or when the truck is just starting its day.

However, after about 15-20 miles of warmup, the truck will shift VERY hard from 1st to second, and occasionally 2nd to 3rd. The overdrive light does NOT come on or flash.

I'm thinking its my type of fluid possibly, but not sure. I don't know what was put in before I bought it (4k miles ago). Is this the possible diagnosis?

 

Pull the codes, you may have some stored even without a light.

 

Sorry. Forgot to mention, no codes.

1-1-1 all around. I know that the computer is logging codes, however. Sounds unlikely that there are no codes, but as far as I can tell, it's a clean truck.

 

The only thing I can think of then would be either be wrong fluid, a failing EPC solenoid in the transmission, or a failing EPC driver in the computer. Possibly a wiring fault when it gets hot, but usually that'd throw a code.

 

Bump. Anyone else experience something like this?

 

Does your speedo ever stop working or bounce? Could be VSS or wiring to it.... That will cause really harsh shifts...

 

No. Never seen any issues with it.

I've only marginally suspected my TPS needing some work. It tended to hunt for idle real early on, but as I replaced all the vacuum lines and cleaned the throttle body, it seems to have gotten better.

 

That's another possibility.. Put a volt meter on it. At idle should be between .80-.99, and as more throttle input goes the volt should go up.. Never goes above 5..

TPS is an input to trans shifting on the E4OD's..

 

Have you measured the transmission's ATF level?.

 

Yes, no problems during all checks at operating temp. completely full

 

I'll try that and report. Thanks

 

Yeah, I think you're having a sensor issue, as has been pointed out. The TPS seems like a possible cause.

 

latechbanjo,

I know this was 6 years ago, but what happened?

Thanks.

 

I'll do my best:

Long story short, the problem still exists from time to time.

The computer was probably trying to throw codes, but the continuous memory was fried as multiple capacitors had leaked out on the ECM. I replaced the ECM, which finally allowed for codes to get through. Coincidentally, the shifting actually started to get worse about a year after the ECM replacement to where it was shifting really hard every drive. The VSS/PSOM code appeared, and that led me to replace the PSOM based on other indications of the speedo and seeing the condition of the circuit board. This mostly cured the problem. It will still occasionally shift poorly, but not nearly as often. The VSS code still reappears, which leads me to believe that I may need to just change the rear diff fluid so that the VSS can read properly.

I also replaced the MLPS with a motorcraft part. It's aligned properly but I find does come out of alignment from time to time. I still believe this is somehow part of the problem.

Remember that the VSS feeds information directly to the PSOM, which then feeds the ECM, which drives the shift points. VSS could be working fine, but a bad PSOM would screw the shifting.

On top of all that, the MLPS could be the culprit if the tranny occasionally shifts out of gear then back in, causing a slam. In my case, I know for sure the PSOM and ECM were bad. Only a separate engine problem led me to replace the ECM.

 

Wow! Quite the journey! Thank you for following up and for the thorough post. I asked because I have somewhat similar.

Mine runs perfectly fine and butter smooth when cold but then shifts harder 2 to 3 (?) after about 20 miles. Around 20 mph. Not whip your head violent but a definite hard clunk almost like it wasn't sure about the shift and then eventually threw it in. If I use drive selector handle and shift manually from "2" to "D" after the point that it would have tried (tiny higher RPM), I can get it to shift very smooth even after the 20 mile mark. All of this is very consistent and repeatable.

Used vehicle and so I don't know history. Could be a bag of tricks but I got it cheap and kinda understood that to a certain degree ... Not my primary vehicle. Trying to read all the threads to glean from them but so far it seems hard to get a progressive step by step. I used a code reader from under my steering wheel but no codes yet. Everyone talks about a flashing light but my selector handle has the od selector switch broken and that is probably where the light is ... Making my cynic mind think that the seller broke it off on purpose so nobody could see the light flash.

Anyways, will keep trying to read. I also need to triple check that I even have the e40d since I am an odd year. 1998 e-350 7.3 diesel. Will check that today by looking for tag and sensor locations.

Maybe need to start my own thread but trying to read others. I don't want people to just repeat themselves.