HI all, i thought i would start here first,I just got this truck two months ago it was running fine ,then it started to shift hard from 1 to 2 , i brought it to the tranny shop he said it was the pump over pumping ,he cleared the code and it was running fine ,and it is doing it again i am going to change the fuild and filter and see if that helps , any help would be GREAT , thanks marvin 1994 150 302 auto od 130,000

 

The PCM (engine and transmission computer) in these trucks controls the transmission hydraulic pressure through the EPC solenoid. The hydraulic line pressure, and thus the firmness of shifts, is a function of throttle position, manifold vaccuum, etc. This function used to be performed by vacuum modulators or TV cables.

The computer can also put the transmission into "performance mode" if it decides something is not to its liking. Common causes include MLPS resistances being out of tolerance or issues with the vehicle speed sensor (VSS, RABS, or PSOM depending on model year). In "performance mode", line pressures are increased and shifts are firmer. This is typically most pronounced on the 1-2 shift. The trans can stay in performance mode even though the computer becomes happy with the input it is getting.

The computer does this to "protect" the trans. Firm shifts are actually better for the transmission, and result in less band and clutch wear, than soft, sloppy shifts. It is a little vexing for the owner/driver. Do a search in this forum and on the internet for "E4OD hard shift" and you will find plenty of additional discussion.

If the problem is only a "thump" from 1 to 2 a couple times on your drive to work, I wouldn't worry too much about it. If it is bugging you, you will have to start pulling and interpreting trans codes to see what the computer is complaining about. The MLPS in these trucks has had a history of problems caused by dirt and water getting into the resistance sensor, and Ford changed it to a different design, which is retro-fittable. Look for other symptoms to help your diagnosis -- trans seeming to be in wrong gear is often the MLPS. Speedometer/Odometer reading wrong is often the VSS.

 

I had a problem with my 92 f150 with the e4od trans also. Whenever I would drive it for about a half hour on the highway without stopping, get off at an exit and then normal city driving it would bang gears really hard. I went to my mechanic and he said replace the neutral safety switch. It is on the side of the trans. where the linkage is and is not to hard to change. It is a combination switch and has a little module in it or something. I was very leniant that it would work but I took his word for it and it now shifts great. Something to try.

 

The neutral safety switch you describe and the MLPS I mentioned are the same thing. It mounts to the side of the transmission and picks up the position of the linkage coming down from the shift handle. It prevents starting except in park or neutral. It also tells the computer what gear you want. If the computer does not believe the input, it puts the tranny into "performance mode".

 

hi guys ,thanks for the replys,it sounds like it will not hurt the tranny untill i look at it this weekend,also i put a new thermastat in and it was a a 180 it should have been a 195 ,would this add to the problem?????? also can i clear the tranny code buy my self,i know how to do it on my motor ,would this work the same way, thanks again

 

Are the tranny codes pulled the same way as the engine codes? Also could you have tranny codes in there without a check engine light?

 

You pull the transmission codes along with the engine codes. The computer will usually NOT light the check engine light in any event.

The best way to clear the memory codes is to remove the STI jumper while the codes are being flashed out. The common crude way is to disconnect the battery for a few minutes. I consider this crude because the computer must re-learn the idle and mixture control strategies when you pull the battery. This is a good thing if you clean the MAF sensor, change ignition timing, or replace O2 sensors. But it is a bit of a blunderbus if you just want to see how long it takes trans codes to come back.

 

thanks guys, like i have read in other posts, i started it up and it ran smooooooooth,what gives ,well i will keep you informed thanks again