[jeesix]

2008 g6 with 3.5L v-6
my problem is when the car shifts to 3rd or 4th gear, (only under light to moderate acceleration) the tach needle jumps up and down about 200 rpms or so, and it can also be felt in the drivers seat as a slight bucking. its especially noticable going up a slight hill. its almost like the torque converter is trying to lock, and unlock. but here is the strange thing, if the car is cold, it doesnt do it, or if its fully warmed up (driven 10 miles or more) it doesnt do it. seems to be the worst just after it hits full operating temperature on the gauge. i have taken it to couple dealers but they either say its normal, or cant find anything wrong. usually i can figure this stuff out and fix it myself, but this one is difficult. as it could be any number of things. anyone out there encountered this problem in either your g6, malibu or aura?
let me know, thanks.
oh, and i did have the flash update done, but it didnt help.

 

[Quadcells]

We are having a simular problem with our 2008 G6 GT. 3-4 shift makes a loud vibration the car sometimes, but the dearler cannot find any problems.

 

[jeesix]

i dont have any vibrations, just as what i would describe as very sloppy, mushy, shifting/torque converter engagement.

 

[Jerrymac]

Torque converter oscillation

When travelling on level road at 45 to 60 MPH with or without cruise engaged, I see a 200 RPM up and down oscillation on the tachometer which I am sure is the torque converter slipping in and out of lock. Doesn't happen at 65 MPH or higher. Vehicle is still in warranty so will be trying to get help from a dealer. Wish me luck. Dealers and I don't usually agree on much. 2008 G6 Base 2.4

 

[jeesix]

yep, thats what i got, never does it in first or secong gear though.
it does seem to be getting slightly worse from when i last posted.
im still under the powertrain warranty, had it to 2 seperate dealers, they either tell me its normal, or can find nothing wrong. like you im certain its a problem with the torque converter. or maybe pressure is too low.
let me know what the dealer says. thanks.

 

[Jerrymac]

Meckanic says "Normal operation"

Just took the dealer's transmission mechanic on a test drive. He said they are making torque converters different than they were a few years ago and that it is normal operation. Said that if there is too much slippage, it will set a code and turn on the check engine lamp.

 

[jeesix]

sounds similar to what my dealer said. if this is how the "new" torque converters operate, they can shove em. back when i bought this car i had a choice between the g6 or a grand prix of the same year. i should have went with the grand prix. live and learn i guess, next gm i buy i will make sure it isnt equiped with this sloppy transmission. or maybe i will "go back a few years" and get an older model.

 

[Jerrymac]

Just took the dealer's transmission mechanic on a test drive. He said they are making torque converters different than they were a few years ago and that it is normal operation. Said that if there is too much slippage, it will set a code and turn on the check engine lamp.

My 08 was destroyed by hail so now have a 10 G6 which has a similar problem. I believe the TCC never locks up on this one. Looking for a way to verify this before taking it to a dealer for waranty repair.

 

[lbostick]

I know this might sound crazy but I just had the same problem with my 08 G6 GT and it turned out to be that two of my plug wires were arching across each other. I only had symptoms in 3rd and 4th gear when going up slight hills. It had me stumped for a while, changed wires and problem solved. Might try it, hope it helps. Also it was not throwing any DTC's.

 

[Jerrymac]

Thanks, but the 2.4 doesn't have plug wires. Coil-on-plug does away with lots of possible problems. Took to dealer yesterday but they had 7 tranny problems waiting for their only tranny mechanic. Will try again next week.

 

[Quadcells]

Hi,
How did you find the arching, did you see it?
I will take a look this weekend.
I have been in and out of the dealer 3 times now. I also been in contact with customer service and thet been helpful getting my car looked at but that's it so far.

 

[lbostick]

Thanks, but the 2.4 doesn't have plug wires. Coil-on-plug does away with lots of possible problems. Took to dealer yesterday but they had 7 tranny problems waiting for their only tranny mechanic. Will try again next week.

My mistake, I didnt see that you had the 2.4

 

[lbostick]

Hi,
How did you find the arching, did you see it?
I will take a look this weekend.
I have been in and out of the dealer 3 times now. I also been in contact with customer service and thet been helpful getting my car looked at but that's it so far.

I actually figured it out the hard way, got a nice little shock when I was messing with the wires, the insulation had started to break down on one of them, not sure why but probably from the heat since they lay right on top of the intake. It ran fine idling and at high rpm's, but stuttered and had rpm fluctuation between 50 and 60 mph when going up hills. Changed wires and plugs and problem completely gone. Figured the wires were arching across each other because there was never a DTC for misfiring.

 

[Quadcells]

I actually figured it out the hard way, got a nice little shock when I was messing with the wires, the insulation had started to break down on one of them, not sure why but probably from the heat since they lay right on top of the intake. It ran fine idling and at high rpm's, but stuttered and had rpm fluctuation between 50 and 60 mph when going up hills. Changed wires and plugs and problem completely gone. Figured the wires were arching across each other because there was never a DTC for misfiring.

Ok, That sounds interesting. Because the service manager at the dealer said he has seen something like that, but instead of the wires it was a cracked spark plug, no codes.
So was it hard to replace the plugs? I have 50,000 miles on my G6 GT, I think I would do the same and see what happens.

 

[lbostick]

Ok, That sounds interesting. Because the service manager at the dealer said he has seen something like that, but instead of the wires it was a cracked spark plug, no codes.
So was it hard to replace the plugs? I have 50,000 miles on my G6 GT, I think I would do the same and see what happens.

No its not really too bad. I'm assuming you have the 3.5 as I do. For the front 3 you can just take off the air intake tubing and get to the front plugs fine, the back 3 are a little tricky but with some patience you can get to them ok. I have read that you can even unbolt the alternator to make accessing the rear plugs a little easier, but I did not. A piece of rubber hose that fits over the top of the plugs makes putting them in a little easier, it prevents you from crossthreading them when you start.

 

[Quadcells]

Hi, Yes I do have 3.5. I'll give it a try. One more question: did you use any special spark plugs or just what GM recomends.
/quadcells

 

[lbostick]

Hi, Yes I do have 3.5. I'll give it a try. One more question: did you use any special spark plugs or just what GM recomends.
/quadcells

I used the stock plugs, what GM recommends

 

[jeesix]

due to some here changing their plugs and wires and solving the problem, i figured i would do the same, but my issue still remains. it sucks, i was hoping it would be an easy fix. doesnt seem the dealerships want to deal with this problem, and its getting worse. im going to have to start going there regularly and making a nuisance of myself until the issue is resolved.

 

[RoseofSharon]

On the right path

I am having the same exact problems with my car that all of you are having and after the holiday my G6 is going to be out of commission because the dealership has finally found the problem this time. They told me today that the torgue converter needs to be replaced. They said that it wont put a light on the dash or throw a code. They figured it out while my boyfriend drove it and the transmission tech had a computer hooked to it. And while the car was in motion it told them what it wouldnt in park. I have had the "reboot" done and it was a temparary fix. So maybe this will help you in getting your car fixed too.

 

[Jerrymac]

Thanks! Please let us know how the repair goes. If anybody has the 2.4, it would help to know what engine speeds you get at speeds such as 40, 50, and 60 MPH while fully warmed up on level road.