Setting up the EPC Trany presure Windstar 96

Hi folks,

Is there anybody who knows the following: Is it possible to set up the EPC presure in the PCM using a diagnostic tool?

The thing is, that my trany is not working good when it's cold. When I shift into D, 2, 1 or R, it takes so much time to shift or I have to increase rpm up to aprox. 3000. If I do this, than the trany goes fine on R, but 1st gear slims a bit. When I drive and stop, than the gear goes out for a while.

Both servos were rebuilt, no change. Than I started to play with that using a digital oscilocsope and all schematics and found, that PCM regulates the EPC presure (using a frequency or pulse-width modulated signal into EPC solenoid) according to fluid temperature, Intake Air flow and TPS. When you increase the rpm, the pwm goes longer (longer pulses) and EPC is than bigger.

I have discovered that it seems, the EPC is regulated low, because when it's cold, the walue is not enaugh to gear the speed. If I have connected the EPC solenoid signal to LOW, the trany works without any problem (not counting the harsh shifts)

I have checked all the vacum pipes, changed the Air flow sensor and everything is OK. What about a Neutral Switch, does it have the same symptoms?

Thanks a lot, if someone has read through this. Just a few ideas about my trany :-)

Since my van is same year, I suggest changing vehicle speed sensor. My symptoms were flashing overdrive light, and I measured some line pressures that were off, the tranny was in limp home mode. I cleared that out by disconnecting battery for a while. It stayed fixed for some time, with some intermittant boughts of low speed issues, shudder or late shift (i forget which). It took some time, then OD light came on again, and tranny shop diagnosed speed sensor.

Thanks for the post, I have this sensor changed 1000km before due to the same trouble codes in PCM. :banghead:

One thing that would be at the top of my list is to make sure that the fluid is fresh.....if over 20K miles.....I would change it.
Also....make sure that the correct fluid is used.....MUST meet the Mercon V specification.

I also mention....though you most likely already checked........the transmission fluid level.
Check with the engine warm.....on level ground.....engine running at Idle, transmission in PARK.....with parking brake set.
If even slightly low....add some fluid to get it just over the FULL mark.

I like to go for the cheap/easy/ normal maintenance items before moving to expensive/complicated.