Thread: 4t65e transmission hard 1 to 2 shift.

1999 Grand Prix 4T65E transmission. When slowing down to about 10 mph if I feed gas I get a hard shift from I guess to 2nd gear. The transmission slams into gear. This is only when warm and intermittent. This transmission IS A REBUILT AND ONLY HAS 4500 MILES ON IT. THE WARENTY IS STILL IS STILL GOOD but the condition has not been duplicated by the tech. I am on my 11 month of warranty.
From a stop the car shifts with no problem. It only happens when going around a corner or slowing down around a yield sign at or below 10 miles per hour.
The fluid level is fine and the rebuilt was filled with DEX 111. The company manufacturing the transmission, American Transmission, here in Florida does not return phone calls. The shop that installed the transmission I believe does not know or have the knowledge to address this problem.
From what I am reading all the problems seem to be on hard shifts in acceleration, not slowing down to 10 miles an hour and then feeding gas.
This problem has happen since day one of the new rebuilt. I have be told to wait until the problem gets worse. It has gotten a little worse.
My question is should I just drive the car this way. Will long term this be more of a problem. I have replace the TPS and the air intake temperature sensor. Don't know what else to do or what the problem is.

Most trans codes disappear when ignition is cycled. Therefore sometimes making it hard to track down. If the condition happens, go have it scanned, but dont cycle the key

BRANDONHALL AND SCOTTYDOGGS When I bought the car back the first time there were no codes or pending codes. I have an appoint tomorrow for the car to be scanned but I doubt they will find anything since the check engine light had never come on. This is what makes this problem so frustrating.

Likely what you're experiencing is called "max adapt". code P1811 ...it's where the PCM think the shift is taking too long, and therefore commands maximum line pressure inside of the transmission, resulting in harsh shifting.