Transmission sometimes make hard changes

On my Windstar95 sometimes is happen following:
I'm standing with the van in idle and then I need to accelerate fast. But nothing is happen - just the rpm goes up but the van will not accelearte, just drive slow And the "BOOM" the transmission is switching very very hard and the everythin runs normal. But this hard changes makes me a little bit afraid.
What can it be?

I too have this problem with my 95 windstar. I also owned a 93 Taurus that did the exact thing. It's a Ford thing. I would like to find a solution for this. It's like a lot of noise and no power. I don't want to pull out in a tight spot.

Anyone out there know anything?

Dan

First off check the fluid see if its nice and pink if its black and dirty it will need to be changed ASAP.... Common problem. The other is the tranny speed sensor...Or computer need reprograming like my taurus once did.
Most likley the tranny fluid need changing.. I have mine done about every 15,000 or when it looks dirty. I use the dealer flush and fill but soon i am going to change the filter myself..

I too have a 95 Windstar and was having similar problems. Mine has 177,000 miles. It finally would not shift into high gear but would operate in low gear. I had the speed sensor replaced which is a quick fix for a shop to do. The part cost $50.00. and the local shop charged me $100. to install it. I have had no trouble since then. With this high mileage I really can't complain about this one. Just don't go to the dealer.

I too have a 95 Windstar and was having similar problems. Mine has 177,000 miles. It finally would not shift into high gear but would operate in low gear. I had the speed sensor replaced which is a quick fix for a shop to do. The part cost $50.00. and the local shop charged me $100. to install it. I have had no trouble since then. With this high mileage I really can't complain about this one. Just don't go to the dealer.

Thanks for the reply from both of you. My fluid is fine, speed sensor is new...I have around 175,000+ miles on this van. I'm the second owner. For a MN van it's in fairly good shape body wise.

I'm wondering if it's the cat or O2 sensors.

Anyone out there with some ideas??

Thanks

Dan

Thanks for the reply from both of you. My fluid is fine, speed sensor is new...I have around 175,000+ miles on this van. I'm the second owner. For a MN van it's in fairly good shape body wise.

I'm wondering if it's the cat or O2 sensors.

Anyone out there with some ideas??

Thanks

Dan
I dont think it will be the O2 sensors, the engine light should come on.. The other option is to have the computer checked out my taurus needed this done.. They reprogramed it..I had the same problem. I called it a confused tranny... Not to scare you but the tranny may be getting ready to let go.Check the CPU first though.You already ruled out about every thing else...

I had the same problem with my 95. It turned out to be the forward clutch piston in the transmission. This piston is responsible for engaging the gears when moving forward. The piston was originally manufactured in aluminum which turned out to crack over time. The crack results in a loss of pressure through the piston, and when the pressure falls too low, the transmission falls out of gear. When you are at a stop, the engine RPMs are at their lowest, so the fluid pump inside the transmission is pumping at its minimum level. Eventually the crack becomes large enough that the minimum level of pumping is not enough to keep the pressure up at the piston, so the transmission disengages at idle. This is apparently a well known problem and is covered by a TSB.

Then you step on the gas, the RPMs rise (a lot since you are no longer in gear), at which point the fluid pump CAN raise the pressure, so it pops the transmission into gear. And since you already raised the RPMs it's quite a rough engagament!

Unfortunately the fix is to pull the transmission and replace the piston with the upgraded (steel) part. Not cheap, but you will eventually stop moving altogether as the crack increases.

Yea, what he said, except it didn't happen to me.