04 impala Shifts Hard when Hot, P1811,shifts hard,jerks

[chevymandan]

Here is the GM customer service rep I have been dealing with 1-866-790-5600 ext 11310. The other # for GM is 800-222-1020. Be sure to let them know about the common problem with their defective transaxles from 97-current. I have an 04 impala with the 4T65E transaxle and with 70,000 miles it shifts hard when hot. This is a common problem with GM. It is suppose to be a defective and poorly designed PCS in tranny, but I think it has something to do with the tranny cooler being a part of the radiator, I might be wrong on that, but call and tell her your concerns. I don't believe enough people are giving GM a fair shot at fixing their problems. After all, how would they know it is a problem if no one tells them. Be sure to leave a message and have your VIN# ready.
Also I have read that the bore in the trans for the pcs expands more than the pcs when hot, due to different properties, which allows a gap creating a loss of pressure. I would like to take temp at the tranny cooler lines while hooked up to the factory tranny cooler which is a part of the radiator, and i would also like to put on a seperate tranny cooler and take the temps of it to compare and see if there is a difference. Everything shifts great except for when the temp gauge is about 1/2 way and then it gets bad. So the theory on the id of the bore expanding more than the od of the pcs makes sense, if so it is an easier fix than a new pcs. PSome people that have had their pcs changed run into the same problem a few years later. But either way GM should have to fix it, since the problem affects vehicles from 97-05 and maybe some newer models.

Calling got me no where but pissed off. But I was able to yell at someone about it.

[chevymandan]

installed the transgo sk4t65e kit, just the accumulator springs, and it shifts great now, not performance shifts, but nice. Took a little over an hour and would recommend it before spending all weekend to change the pcs

[RjWood]

It can also be a slip within the gears and when that happens it cause it to throw a code which would be the 1811 max adapt long shift which in turn shuts off pcs and max's out transmission line pressure which then results in a hard shift and that will happen when ever your computer reads that you didnt shift fast enough so it automatically trys to fix the problem. I had the same problem and ended up doing a valve body reconditioning replaces clutches and plates to a performance model and a new filter and this was at 118,000 and i now have 143,000 and it still drives like the day i got it.

[chevymandan]

I was dreading changing the pcs, but it was easier than i thought. I am not a mechanic and I am not suggesting that you do this, this is what I did and it worked fine and saved a bunch of money and was easy to do. Anything you decide to do is your choice and I am not liable for it
1. disconnect battery and drain transmission fluid, put transmission pan back on with a few bolts, you can change the filter when you are done with everything else and put all the bolts back in
2. take off air filter housing and air intake, take electrical plug out of transmission
3. raise boot on steering gear box and take bolt out of steering connecting to steering shaft, it is one bolt and has to come completely out and then slide the shaft up off of it (this is done so you do not damage the steering when you lower the cradle)
4. loosen axle nut and lug nuts so you can get them off when you raise the vehicle.
5. raise vehicle,and support it,take off the following only on drivers side: wheel, brake caliper (hang out of way), lower ball joint off of lower A arm, tie rod end, sway bar
6. now you can take out the 3 strut nuts from up top and tap on the axle nut very lightly, then take the axle nut off to get it out of the front hub assembly,
7. push down on the lower A arm, and pull the strut out (i left the strut, rotor, front hub assembly as one when i took it out), also take out engine splash shield which has 3 plastic rivets in it, then pull out axle, i used a slide hammer
8. I had 3 different areas of support , the body, the transmission, and the front drivers side cradle
9. I placed a piece of plywood on the jack and used it to support the transmission, be careful not to raise it to high and crack your coolant reservoir
10. I placed another jack on the cradle
11. I used jack stands to support the body
12. I took out the tranny mount nuts that bolt it to the cradle.
13. With the tranny supported, as well as the Cradle, I loosened the 2 drivers side cradle bolts and took them completely out. Lower the cradle down. This allows you to get to the bottom bolts of the side cover. Then lower the transmission down to get the rest of the bolts out.
14. Pull off side cover and replace solenoids. Disconnect wire harness, they have a pin that you must pull out with needle nose pliers, pull out solenoid
15. Reverse procedure to assemble
16. got alignment

This job took about 5 hours, because it was my first time doing it, but it is real easy
I bought a solenoid kit off ebay for $108, fluid and filter for about $60, I used about 10 qts

every car is different so use common sense when you are working on it, you have no one to blame but yourself if you screw up, good luck