O.k., I have the 4l60E and about a month ago on the way home from work the tranny starts shifting real hard. I get home and check the fluid (w/ the car idling in park) and it is low so I add some fluid. The next day the car runs fine. About two days later it starts shifting hard/rough again eventhough the fluid is still full. So I change the fluid and filter. The pan is fairly clean, there is only normal wear (no excessive shavings) and the valve body looks good.
So fast forward three weeks later the car has been shifting fine with no problems since then. Yesterday it starts doing the same thing after driving for about half an hour. I check the level and it is very close to full, it only took maybe 1/7th of the quart to fill the trans. I make the 35 min. drive home after that and it shifts fine.
Today I'm driving for ~30 min. and it starts shifting hard again. I check the level and it's full. I let the car sit for maybe ten minutes and then make the 30 min. drive back home and it shifts fine like nothing every happened???
What could be causing this? The fluid was full last time it did this. I've changed the fluid twice in the 30,000 miles I've had the car. The fluid doesn't smell burnt and the trans isn't slipping it is just shifting rough occasionaly. I baby the car and it only has 63,000 miles on it.
Any ideas? Could it be the computer or a sensor or maybe some shift linkage??

Thanks

 

sounds like something is clogged

 

I think so. I just talked to my friend who is a mechanic and he said he thinks one of the valves is sticking. He said I could remove the valvebody and clean everything out and it should work fine.
Does this sound right?

 

Check the pcm for codes, especially a P1870. There was a problem with the tcc reg. valve wearing in the valve body, causing excessive tcc slip. When the pcm sees this slip, it sets the code (doesn't turn the Check Engine Light on) and max's the line pressure. The high line pres. causes the harsh shifts. Typically the next key cycle, the code goes to history and the line pres. returns to normal. This is why it is intermittent. It's most common on highway driven vehicles where the tcc is used more often. Hope this helps.