The problem I had, came back... In my intro to being a new member I had mentioned this problem went away, but it came back shortly after I said this.

Anyways, here is what it is doing...

When I am at about 12mph, if I nudge the gas quickly the transmission shifts hard.
Does the same at about 45mph.

It randomly does this.

When I first got the car, it would have a random kick feel at low speeds like I said... but not at other speeds it seemed.
My first repair was this:
-PCV valve replaced
-Vacuum line to PCV replaced as it was cracked

The car seemed fine after this...
But then it started but not as frequently again!

I checked the tranny fluid level and it was over filled.
I have a feeling the slight incline of my driveway gave me a false level read.
Therefore it was topped off too much.
Probably around 13oz over.
I don't drive the car a lot. So, it wasn't driving around over for too long like this I believe.
I drained and topped as needed to get the level to what I thought was dead on.
Just level to the XXX, and not much more... so I thought.
I did this on level ground and did the topping off after driving it a couple miles.
I also spotted a cracked vacuum line that was coming from the throttle body.
I replaced it, and it was conected to a long spaghetti preformed line goes to a sensor heading to the rear top of the motor.....That line I am wondering if it is a pressure sensor for fueling. If it is, I accidentally had it pulled a little bit and it made starting the car hard.
I pushed the connecting line back onto that sensor and it went back to the car being easy to start.
I think when they rebuilt the motor, someone was working with those 15 yr old vacuum lines and two that I know of cracked.

The line that goes onto that sensor can shift left and right, in other words it is tight on or loose.
I think the sensor used to lock the hose line onto it, and when it was removed the lock was broke and it is just pressed onto it now.
I will have to take pics.

The problem seemed gone when the cracked line was replaced and fluid adjusted, but came back.
So, I checked the level again and it was over.... Alrighty then...
How this happened after checking over and over is beside the point.
But I did pump the excess which wasn't much out.

I drove the car, and it is less on the phenomenon, but it is still a problem.
Less times happening and less of a "buck" feel.
Still not fixed though, it acts like the fluid level is low.
I am looking at the dipstick and it is very close to the top of the XXX.
So I am a little frustrated.

The car is under 100K miles.
The engine was rebuilt around 93k miles.
I assume that since the motor was out that the tranny got new fluid and new seals.
It isn't leaking... but this phenomenon is eluding me as to what it might be,

I am thinking it might be:
A) Tranny pressure sensor going bad
B) That sensor I had mentioned that is connected by a long plastic looking spaghetti line from the throttle body need replaced
C) For some reason the dipstick is way inaccurate and I have a low fluid condition

If the tranny pressure sensor is the culprit, does anyone have a pic of its location?
I would prefer to do the work myself.

Any input and help is much appreciated.
Thank you!

 

As far as the dipstick. Dipsticks are known to be inaccurate (trans and/or oil). Change fluid again, and add the correct amount of fluid (including starting and shifting thru the gears) based upon the service specs. Since you know the trans now has the correct account of fluid, that will be your full mark regardless of what the dipstick says.

If the dipstick shows something other then full, I would use a little file and add my own full mark.

Just my 2cent worth (worth less than a penny these days).

 

Good information from JackDW , I would add this thought put some Trans shift fluid in it I use the Lucas Oil brand about a quart. There are other brands that are good too.
Then I would just replace all the Vac lines that I could find. Sometimes they get a gue on them and leak. There is a larger one that leads to the firewall someplace I recall and that one slipped off on my friends Monte and it wouldn't start until I found it off and reattached it.
Also with the dipstick thing maybe when they did the3 engine repair they pulled that dip stick and then lost it and replaced it with another they found. Seen that once or twice. anyway if you get to a salvage yard and you can find one there as a replacement.
Good Luck

 

Unless you've got some evidence that may point to that, I wouldn't automatically assume it.

I've seen plenty of people pull / replace one without touching the other. They're two of the most expensive components to rebuild in the whole car, so often people dont want to spend the money to redo both together.

 

These are good tips, thank you all.

I did look at the transmission fluid, and it is a good pink color and looks good.

I didn't see any transmission leaks.

The dipstick might be the wrong one, so I will have to see how much a new one will cost and perhaps even do a comparison visually of the new one vs the one I have before buying. But of course sometimes they don't take pics of the actual item. But, I figure if it looks the same, whats the chances... so it would be assumed that I have the correct one if they match.

I think I am going to just drain the transmission and refill like suggested. This way, I know the level/ amount is correct. Good suggestion.

Now I got to get under the car and locate the drain plug for the tranny.
----> Did Chevy on this car make it so it needs some fancy machine to fill like my 07 Cobalt???
I was mad they made it so it has to be serviced by someone that has that machine that hooks up to the transmission to service it.
Hoping the 05 Monte SS SC is not that way. I assume it isn't since I actual have a dipstick for the tranny whereas the Cobalt doesn't.

As an update, I tried resetting the computer to see if this would fix this problem, as it doesn't cost anything.
I drove it around and no shift problems. Seemed to work fine for my wife today also.
But... I don't want to assume all is 100% at this point. Not enough driving to make me feel like all is good.
The tranny can start shifting hard again tomorrow, who knows?

I have had non-smooth shifts on other cars in the past and computer resetting has fixed the problem.
A Dodge, a Chevy and a Pontiac.
Seems like if some factor changes or the computer is not reset correct, the shifting is not as good.
Seriously... I guess the computer collects info over time and when something changes like a line cracks or something like changing the fluid level the computer applies commands in reaction to the sensors and they don't jive because some factor has changed. Instead of driving a lot of miles to let the computer figure it out, I rather reset it.
Not sure if it on its own would be able to compensate for new factors once is nestles into its parameters or not.

Either way, I need to just get a new dipstick, drain the fluid and start anew.
Thank you guys!

 

There is no trans drain plug unless it's an aftermarket pan. Just have to unbolt the pan slowly to drain it from one side (loosen one side more than the other).

Fill is standard- just through the dipstick hole, so it's a bit slow, but otherwise normal.