Prozium

I have a s4 that has an automatic transmission and it runs fine for a while then it doesn't want to shift and the car starts to run like $#!t. if I leave it for a day or 2 it starts to work again. I am not low on fluid, so what can it be?

satch

iTrader: (1)

Besides the fluid, the next place to check would be the "vacuum modulator," which is bolted on to the side housing of the transmission(driver's side). There is a vacuum tube connected to the modulator. Disconnect it and check for "any" fluid in the tube. Since the tube is for vacuum only then air should be the only thing present. If there is fluid then the modulator has failed and needs replacement. Also, check to see how the transmission reacts if you change the overdrive switch position from its current setup. Meaning if you always drive with the overdrive button not engaged then engage it and see how the car performs over a period of time such as in a number of days. Perhaps the overdrive solenoid is problematic. Lastly, look at the FSM and look at the chart depicting all the problems listed and see which one most closely resembles your problem.

Prozium

thanks for the tips, I will check them out this week/weekend and see if I find anything.