I have the same problem I change the tranny fluid and filter but it still does it from time to time. Accelerating from a Dead stop tranny seems to slip for a fraction of a second and then it hits. If I accelerate smoothly no problem but if I should take off quickly then that’s when the symptoms arise. I don’t have any engine code lights coming on I took it to a transmission shop and they visually look at my transmission and could not see any problems. They suggested it was my motor mounts. I found the service records for this vehicle and the prior owner noted this symptom when the car only had 40,000 miles on it relatively low mileage. I come to find out That The original owner know that that symptom when he brought it in for service to a local shop. Did you eventually remedy the problem if so drop me a line I seen your reply you did something with the PCM

 

IMO, tweaks to the pcm to make this go away is just a bandaid. If it's the engine mounts, this should be able to be determined very quickly with a visual / manual inspection. If the mounts are so blown out that the engine is flapping back and forth enough to make a noticeable lag in takeoff, this will be very easy to spot.

Typically the problem with this is the input clutch piston seal. Due to the poor design (particularly with the short style seal) it can easily lose its ability to seal properly with wear. The leak is relatively small and the pump can easily overcome it with more volume, but that's what is causing the lag - waiting for sufficient volume / pressure to build to overcome this leak..

There are other possibilities - particularly a lack of fluid at low rpm due to a really plugged filter, but if that's been changed and it's still happening, then the problem is internal.

Unfortunately this is a common issue on 4t65s. I've owned 2 like this- an 08 Impala and a 07 GP GXP. The impala started it about 65k and the GP started around 50k

 

There is another thread on here and some guy that is very intelligent knew EXACTLY what is causing this, and yeah, it's a glitch in these trannys. My MC and Impala both have done this same thing. Found this thread when searching for the other one.

 

I just got a 2003 Chevy Monte Carlo from my father about 2 months ago the head gasket went out and I tore the engine out of replaced it all by myself first engine job I've ever done and it's running great it recently just started slipping at complete stops and catching and if I'm driving it for more than 2 hours it starts to kick really hard when it shifts but if I sit for 5 minutes it stops doing it and we'll start doing it again after like an hour or so once the fluid heats up again I'm assuming. But this car has 209,753 mi and it just started doing it I get no engine codes no delayed shifting codes and pretty much every time it shifts it goes up to like 2 to 3,000 RPMs and hesitates for about 5 seconds and then drops down if I'm driving though and I let off the gas it shifts perfectly fine unless it's been driven for a couple hours and it still kicks hard but my dad just did the filter change and we're going to do it again he did it like three times on a Tahoe he got from my grandma when she passed away and after about 5 filter and fluid changes it shifted perfectly fine for another 150,000 miles. I don't know I think maybe I just got lucky cuz everybody seems to have problems with those transmissions way sooner but mine just now started

 

You keep the fluid changed and a tranny can go a long time. My MC has 164K and shifts just fine, except for that random lurch I get when I take off from a dead stop. Nature of the beast with GM trannys. Had a 2007 Impala with 190K and original tranny.

Most people rarely change the fluid, and therein lies the problem. I change mine every 30K and use Dexron VI synthetic Valvoline. Your tranny fluid only gets as hot as your engine as the cooling lines run through the radiator. Your temp should run just a tick above the last mark before straight up and down on your gauge. That's right at 190. Might run hotter if you are in town traffic a lot.

 

It's definitely not every one, despite my personal mixed success with them, my Dad did own one that made it to 225k without a rebuild (and the car was totalled, so it certainly may have kept going longer). I do think its a statistics game though as of course his sample size is 1 vs the 6 I've owned.

 

For anyone reading this after all these comments having the same issues. I would start with checking your TRANSMISSION CONTROL MODULE. Brand new they are a little expensive. (over a $100) but you can test them with the right meter. Also I seen a few people who got one at a junkyard for $20 and got lucky. But it seemed to fix alot of tranny problems on these Monte Carlos. Just a thought. Shift solenoids are kinda cheap but unless you can work on cars the labor will cost you a ton.

 

For anyone reading this after all these comments having the same issues. I would start with checking your TRANSMISSION CONTROL MODULE. Brand new they are a little expensive. (over a $100) but you can test them with the right meter. Also I seen a few people who got one at a junkyard for $20 and got lucky. But it seemed to fix alot of tranny problems on these Monte Carlos. Just a thought. Shift solenoids are kinda cheap but unless you can work on cars the labor will cost you a ton.

 

This man is exactly right. Talked to a local transmission shop, and some companies are already addressing the problem in their rebuild kits, and actually using a weaker spring that holds the reverse piston. Clearances are also a bit different, and they are using aluminum pistons instead of plastic. Just pulled mine and having it gone through to eliminate this crap. It is like having a tranny brake in the car. It will actually chirp the tires sometimes. Enough.