2.4 L auto with weird RPM fluctuations
03-28-2012, 11:26 PM
#1
New Member
Thread Starter
Join Date: 02-28-10
Location: Rapid City, SD
Posts: 15
Likes: 0
Received 0 Likes
on
0 Posts
2.4 L auto with weird RPM fluctuations
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!
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!
03-29-2012, 12:37 AM
#4
Senior Member
iTrader: (17)
Join Date: 09-03-10
Location: motor city
Posts: 2,750
Likes: 0
Received 0 Likes
on
0 Posts
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.
03-29-2012, 12:42 AM
#5
New Member
Thread Starter
Join Date: 02-28-10
Location: Rapid City, SD
Posts: 15
Likes: 0
Received 0 Likes
on
0 Posts
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.
03-29-2012, 12:47 AM
#6
Senior Member
iTrader: (17)
Join Date: 09-03-10
Location: motor city
Posts: 2,750
Likes: 0
Received 0 Likes
on
0 Posts
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.
and let them reflash you with an updated TCM flash, then see if vince will let you get another trifecta flash for free.
03-30-2012, 11:51 AM
#8
New Member
Join Date: 03-09-11
Location: Moreland, GA
Posts: 142
Likes: 0
Received 0 Likes
on
0 Posts
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.
04-01-2012, 12:56 AM
#10
New Member
Thread Starter
Join Date: 02-28-10
Location: Rapid City, SD
Posts: 15
Likes: 0
Received 0 Likes
on
0 Posts
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.
04-07-2012, 10:48 AM
#13
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.
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.
04-07-2012, 01:30 PM
#14
Banned
Join Date: 02-23-12
Location: Florida
Posts: 209
Likes: 0
Received 0 Likes
on
0 Posts
, just a little bit of slipping but its not like it didn't do that before hand. ******* rental car.... 
04-10-2012, 02:42 AM
#17
New Member
Thread Starter
Join Date: 02-28-10
Location: Rapid City, SD
Posts: 15
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
04-10-2012, 01:00 PM
#18
Senior Member
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.
