Ok I have been searching the forums for a long while now before posting. The only related thread I've found is:

https://www.cobaltss.net/forums/prob...l-4t45e-81369/

But I can't seem to find a definite answer to what I'm experiencing. It is a little hard to explain but here it goes:

I've been experiencing this for a while now but it has slowly gotten worse. If I'm cruising, approx 40 - 65 mph under moderate throttle, I'm seeing some weird RPM fluctuations. To me it feels as if it's between 3rd and 4th gear. It's like my car wants to shift, but then decides not to. Sometimes it will do it over and over and over... I'm not sure if it a TCC lock-up problem, a problem with the TCM, or something else.

Here is a link to a video of what's going on:
Getting weird RPM fluctuations - YouTube

Right now I have a K&N SRI and a Trifecta tune. I've sent a few logs back to Vince and he's said that there doesn't seem to be anything wrong with my air/fuel ratios. I've unplugged my battery, reset the TCM adaptives, tried replacing the evap purge solenoid, new battery, checked bolts up and down my exhaust (no leaks from what I could tell), replaced my MAF sensor (after getting my K&N), cleaned my intake manifold and throttle body, seafomed..... All of which to no avail.

Resetting the battery and/or TCM adaptives works for a little while, but then the problem just reoccurs within a few days to weeks depending on how much I drive.

I'd like to replace the TCM and see if that takes care of the problem.. Maybe there is updated software for the new ones??? Not sure if it will help or not. It was suggested at the end of the thread I referred to at the beginning of this post. I did post that I was considering even replacing the TCC solenoid if it comes down to it but I'm not sure I want to go through the hassle. I have two roommates who are both very proficient when it comes to working with cars and transmissions so I know we could get it done I'm just not wanting to if there is a different solution.

So with that, is there anything anyone might recommend or have an idea what the problem might be? Is anyone else currently experiencing this? Has anyone pulled apart the 4t45e transmission? How hard/difficult would it be to get at the throttle body?

Sorry I know this is a long post/rant but I'm sick of dealing with this problem. I drive 600 miles or more ever 2 to 3 weeks and I want it fixed! Thanks in advance for any suggestions!

 

Thats a problem with the TCM tune, Vince should be able to fix it. It seems it either cant pick a right gear or the overdrive keeps turning on/off

 

I guess I forgot to mention that it was happening before I got the tune. Still think he should be able to take care of it? Thanks!

 

Still the same symptoms then, either TCM over-reactive to gear changes or overdrive coming on/off too quickly. First I would suggest changing the transmission fluid, while leaving the battery disconnected for a longer period of time (> 1 hour) then go from there.

 

Ha I must be more forgetful that I thought.. I didn't mention I did that recently too. I just checked it the other day in fact. Let a little more than a quart drain out. Color seemed fine not burnt smelling or anything (that's what my Chilton manual said to check for anyway). I just put more new fluid in to replace what I drained.

 

Haha its all good. I'm positive that its a problem with the TCM then, your only really option is to take it to the stealership and let them reflash you with an updated TCM flash, then see if vince will let you get another trifecta flash for free.

 

Dang...

Oh well better than tearing apart my tranny. I'll see what I can get done and repost! Thanks for the advise!

 

Wow, I thought I was the only one with this problem. Lol. Iv never been able to find anyone talk aboit it before so i thought it was just me. My 06 2.4 auto does the same thing as yours. Iv also got the k&n intake but I'm on stock tune. It gets really annoying.

 

Ditch the TFT i had the same problems, its not the tranny...

 

It was happening before the tune. I'm running stock right now except the SRI and it's still happening. Unplugged the battery for a while before going back to stock. Worked for a while, then same stuff came back.

 

I had the same problem with the TFT, misfires, random rpm surges etc. Thats why i figured soon as i went to HPT cured all those issues

 

Any cure for this yet? I've been into the dealership twice and they "fixed" the problem only for it to come back again. It's not terrible its just bothersome and I just want to make sure its not destroying my transmission.

 

That doesnt seem like a lock engage/disengage (RPMS would flex more because the converter drops the RPMS a lot)

TCC clutch slip? My minimum duty cycle is 50 all across the table and 100 on the maximum table so its instant engage/disengage and theres no more slip.

 

If anyone is destorying there tranny its me with the TVS , just a little bit of slipping but its not like it didn't do that before hand. ******* rental car....

 

You have your tune handy i could look at? Would love to see trans settings

 

hahaha its true

 

I haven't taken mine to the dealer yet. I called to see if they could flash a TCM update and they told me between $100-$200. Not exactly wanting to spend the money on it just yet. It's still happening.. Just gets worse, unplug the battery a while, it gets better until I notice it again or it starts to bug me. Repeat. Very frustrating.

nhanson, I'm not sure I know what you mean by the RPMs would flex more.. And if it is a TCC clutch slip like you suggest, how could I check to see if this is the problem?

I have read that if its a TCC lockup problem, I could drive at cruising speeds and lightly press the brake and it should go away. I've read it on the forums here as well as other places. But I've tried that and it doesn't seem to work. RPMs still bounce like the video.

 

My 2006 2.4 ss auto is the doing the exact same thing. It even does when the car is in park. I've tried getting a different tune and it still is doing it. People are telling me to try and clean my k&n filter and my throttle body.

 

Maf too

 

From the look of that vid, i'd have to say it's a TCC lockup issue.

 

I've had this issue for two years or so. Just learned to deal with it lol. I tried everything I could think of

 

Same issue here like what Mindrot said " just learn to deal with it" no cobalt is ever perfectly made

 

Only difference I have with the OP is that the issue isnt getting worse.

 

Mine isn't getting any worse either. It's just annoying to have to deal with it. Took it to the dealership and they said it was fine an proceeded to tell me it's because my car sits too low forthw transmission to function properly. Da fuq?

 

Quite interestingly enough this minor issue went away after my turbo build