I have an 06 Ford Freestar and it may sound crazy but the transmission seems to slip at around 40-60 mph ONLY when it is snowing! I have had it in and out of the shop and they can’t get it to duplicate. Everyone who has been in the vehicle when it happens has felt it and it is definitely not the tires slipping in the snow. It just seems like the transmission is shifting and there is a delay in the shift. There are no other signs of any transmission trouble and fluid level is fine!
Any Suggestions?
There is nothing about snow itself that could have anything to do with this - unless it was the tires slipping. (So, yes it sounds crazy - I’ll bet the people at the shop are looking at you a little funny).
Are you sure it isn’t temperature rather than snow?
Are you sure it is about the vehicle’s speed rather than about RPMs, acceleration, deceleration, etc.?
Does this vehicle have traction control?
Does it have a continuously variable transmission (CVT)?
It could be the traction control engaging.
Does the Freestar have traction control, I probably should know but I am not much of a minivan man! If it does should it be that noticable?
Sometimes traction control is an option - I don’t know if it was optional or not on this vehicle. Look in the owners manual to see what it has to say about it.
I have a 2004 Freestar that did the same thing. I had the tranny fluid changed, had the the tranny bands checked for proper adjustment, checked the O2 sensor to name a few possible causes. It turned out that the MAF (Max Air Flow) sensor was hyper-sensitive to being even a little dirty. I had my mechanic clean the MAF sensor and it was good for the rest of the winter. I found instructions on the following link: http://www.fordf150.net/howto/clean-maf-mass-airflow-sensor.php
I have to post a correction to my previous post - it the MASS Air Flow Sensor that I cleaned on my 2004 Freestar, not the “Max”. Also, the link I listed was for an F150, but the steps should be the same.