Navy Man

I'm making this thread for the purpose of giving people helpful information if they are having similar issues with their car. This will be a progress report of how I solved my problems.

The car: My car is a 2004 Impala with a 4.3 engine and 4T65E automatic transmission.

The skinny: The issue I'm having is twofold. Firstly, on occasion, after stopping at a stop sign or stop light, and I proceed to go, the transmission hesitates, and then jerks forward as if it starts out in too high of a gear and then slams into first. It only does it on occasion though.
Secondly, again, on occasion, after speeding up and slowing down a lot, (city driving, windey roads, etc.) the transmission begins to shift hard through all gears. I can stop the problem by pulling over, shutting the car off, and starting it back up.
I know it is not a bad transmission because it works perfectly most of the time, and the shifts are good and solid; no shuddering or slipping. I must therefore conclude that it is a transmission control issue.

Corrective actions: I have changed the oil and filter and the problem still exists. I also added some Lucas transmission fix. This reduced the frequency of the problem, however, it still exists. My next move is to change my solenoids inside the side cover of the transmission. I purchased a valve kit from ebay for $80. The kit includes 5 items: shift solenoids 1&2, torque converter control solenoid (TCC solenoid), pressure control solenoid (PC solenoid), and a transmission fluid pressure valve assembly (TFP valve assy.) These are all AC Delco brand and still in their packaging. They also come with a parts warranty. (I mention this because you have to be careful buying parts off ebay. But you can save alot of money if you know what to look for.) Although the pressure control solenoid is my prime suspect, I am going to change all of them while I have it open, because, according to my research, it is a big job to get in there. I will do this tomorrow (13-JUL-2013) and post my results.

Navy Man

Okay, I just finished changing my solenoids in my transmission. It was hell. I did not change the two shift solenoids though. I had little room to work with, I was running out of time, and the current shift solenoids are working just fine. It took me seven hours to complete. I could have done it quicker if I knew more about what to expect. Figuring out how to raise and lower the subframe independently of the engine wasted some time. Never-the-less, I can certainly tell a difference in the way it shifts. Before, every time it shifted, it felt different. Some were quick shifts, and some were hesitant. Now it is a consistent quick shift every time. I drove the car on a sixty mile trip right after getting finished and so far, it has not had any hiccups. Time will tell if it is fixed for good. I will post back later with an update on how it is doing. I hope some other people can find this information useful. After all, the 4T65E transmission is used in many cars.

Navy Man

So it's been about a week now since I changed my transmission solenoids and so far it has not had one hiccup. I think it is safe to say that changing those things fixed the problem. If anyone would like some pointers on how to go about doing that, let me know and I'll share some knowledge.

400k

Navy Man,
I recently bought an 04 Impala that is showing the exact same symptoms on the transmission. It is very random, but when it "kicks" at a stop light, it is pretty rough. We tried turning off the traction control, but it did not help. I suspected an electrical problem, rather than a bad transmission. Please post the exact solenoids that you changed out, so I will know where to start. Also, a little more info about the subframe being in the way would help. My car is the 3800 so I will have to see if it has the 4T65E or not, but regardless, it is the same problem.

Navy Man

I'm guessing you do have the 4T65E transmission. That seems to be a widely used transmission. The solenoids are located inside the side cover of the transmission on the driver's side. You have to take apart the wheel assembly and remove the C.V. axle because the C.V. axle runs right through the cover you need to remove. The sub frame is what the engine and transmission is mounted to. It is held on by four large bolts; two in front of the wheels, right behind the bumper, and two behind the wheels and in towards the centerline of the car a bit. The lower wheel lever is also mounted to this frame. I detached the upper motor mounts under the hood, and I would also recommend removing the intake tube between the air filter and the engine because the engine will need to lower quite a ways in order to get the cover off. Additionally, you will need 7 to 8 quarts of new oil because you will need to drain most of your oil. I would recommend jacking up the car and setting it on jack stands. Set the jack stands behind the subframe though. Loosen the bolts around the transmission oil pan and drain as much oil as will drain without actually taking the pan off. If your transmission oil has not been changed for a while, you may just want to drain it totally and and replace the oil and filter. Then, disassemble the wheel assembly. You will need a 34 MM socket to remove the nut in the center of the hub. You do not need to disassemble the strut assembly though. You just need to be able to swing the wheel bearing housing out far enough to get the C.V. axle out. When removing the two bolts holding the strut assembly to the wheel bearing housing, take a sharpie and trace around the bolt head of the upper bolt. This bolt adjusts your alignment and you want to be able to put it back where it was. After all of this, get a pry bar with a curl at one end and use it to pop the C.V. axle shaft out of the transmission. Be careful not to damage the seal, especially when you are reassembling it. Then, using two jacks, put one jack on the driver's side of the subframe and one jack on the passenger's side, unbolt the subframe, and lower it down. Watch carefully as you lower it that nothing gets pulled apart. Additionally, it can only lower so far because of a steering linkage behind the transmission connecting directly to the steering shaft that runs up to the steering wheel, unless you want to detach this as well. Using a third jack, position it under the engine oil pan on the side closest to the driver's side, so you can move it up and down independently of the sub frame. Put a wood block between the jack and the oil pan to avoid damaging the oil pan and jack it up enough to support the engine/trans so you can remove the engine/trans mount. Then remove the side cover bolts that are accessible. You will also need to unbolt the shifter cable bracket to access one of the cover bolts. Remove the engine/trans mount and jack up the engine/trans to access the cover bolts along the bottom.*Four of them are torx head bolts so you will need some torx drivers. Once the pan is unbolted, be careful not to damage the gasket. It is a metal gasket with a rubber seal so it is re-usable. Do not use silicone to put it back together either. This is not necessary. Pull the cover out as far as you can get it to give you the most room to work in. I was not able to pull it out all the way. One of the pictures in the following link gives a breakdown of the components under that cover. http://www.justanswer.com/pontiac/2tauq-reverse-no-attempt-shift-3rd-4th-gear-fluid-level.html
The components in the picture you will be concerned with are 334, 322, 395, and if you want to, 315A and 315B (shift solenoids). All of them are held in with a little clip that is easily removed except component 395, which is held on by three little bolts. For the others, unplug the component, being careful not to break the holding clip on the plug, remove the retainer clip, and pop the solenoid out. Then pop the new solenoid in, replace the clip, and plug it in. Once this is done, just reassemble the car in reverse order.
Before beginning the project, I would recommend that you verify with the dealer that your parts are correct, especially if you get your parts off of ebay. This is a big project, and would be very frustrating to have to put it on hold while you wait for the right parts to come.

CajunGurl

I am new here, but I own a 2004 Impala SS. The 3800 series II. Sometimes when I shift out of park, my car makes a popping noise, what could that be from? Also when I shift out of park on an inclined parking lot. Good lord it sounds like my babies transmission is falling out. I know the basics about my car, but not this. Please help.

400k

Navy Man,
Thanks so much for the detailed info on how to install components 334,332,395, although I have yet to look up "just answer .com" for more details. Hopefully, this link will save us a lot of hassle and money (instead of taking it to a GM dealer.) My youngest son has gotten into other makes (besides GM) where he works, so I am confident we can handle it. Looks like a "weekend" project! Thanks again for your time.

Navy Man

I have heard my car make some sounds when I put it in gear. Mine sounds like it's just the slack being taken up in all of the gears. However, a car can make alot of noise when a motor mount is bad. You can have someone observe the engine while you shift it into gear from park. If the engine moves a lot, that would be a sign of a bad motor mount. The engine should move a little, (maybe 1/2 of an inch) but not much.

Ranger Rick

I have a 2004 Impala LS with the 3800 and 4T65E transmission and have had these shifting problems since it hit 210,000 km. I was able to offset / smooth out the jerky shifts with the LUCAS automatic transmission CONDITIONER fluid until around 400,000 km (had to add it every 20,000 km) but it just got worse and more jerky. I almost bought a used tranny at a wrecker but got a revelation into researching first and found out the PCS was the likely culprit. I went to You Tube and found several videos on how to do this fix there... I then went to a You-Pull wrecker and did a dry-run on an identical 2004 LS there. There is no doubt about this... it is a large job. I did it in my garage using two jacks and it took 12 hours to do over two days... but I am slow. I will warn you - if you do this job, MAKE SURE you get the right Torx bit for the lower tranny case bolts and MAKE SURE you clean them out thoroughly before attempting to take them out. Also - I disconnected the rack and pinion unit from the subframe and suspended it, rather than disconnect the steering column from the rack, as I heard it is a total -itch to get back together again. This worked just fine for me. And make sure you loosen the subframe enough on the passenger side else the drivers side sub frame won't drop enough and you won't get the tranny case off all the way (which happened to me initially and was VERY frustrating)! Also - make sure you disconnect the accelerator linkages up top or they will hang you up and not let you lower the subframe enough. Also make sure you have something good to pull the CV shaft out of the tranny - otherwise it will separate on you. And when putting the case back on... I used a very light bit of tranny friendly silicone to keep the gaskets in place. The little round one around the CV shaft was especially a nuisance to keep in place when putting the case back on. Try NOT to damage the main gasket as they are over $100 here in Canada.

Anyways - all the best - I did the job twice (once on wreck and once on my car) and it is a big one. I changed ALL the solenoids in there with dealer parts - didn't want to risk putting in crap. It cost me about $300 Canadian for them all up here. As for the result? It has been running now about 1-2 months and the car has done about 5000 km and so far, so good. Lets say $300 alot better than $3000 for a dealer remanufactured, $2000 for a rebuild, or $1800 for a used one (cleaned, serviced and installed).

UPDATE - Nov 15 2015- have put about 20-30000 km on transmission since doing PCS and other solenoid change - still working ok. I have changed tranny oil and filter twice since then too. If you do this job, make sure you use quality parts and filter - read about a guy doing it but used a cheap filter and the filter started losing bits and clogged the PCS again. It's a lot of work to do this job - make sure you use quality parts and are very clean when in there and doing fluid change! All the best of luck to those of you who decide to take the plunge!

bac1961

It started slipping over 1 week ago. Then one day, put it into Drive....nothing would happen. So I shifted carefully manually, now it does not work at all. I even added some Tranny fix a few days ago. I could not even make it up a hill, let alone barely make it back home. No recalls yet have been posted on the GM site.