TheBlizzard

In 4th gear under a 30-50% load with the rpms at 1500 my car will jerk and lurch like it is missing. The rpms will jump to 2000 then go back down, the torque converted will not unlock and it will not downshift unless I really step on it a lot.

I have done my own research, the only thing I can come up with is one of two things. It is the displancement on demand kicking on and off, or the torque converted in the transmission is starting to go out.

I really need an answer because I still have a powertrain warranty on the transmission until June 2012.

Any input is greatly appreciated.

Car in question is a 2008 GXP with 70k miles, bone stock, stock transmission with Hayden Cooler.

SRTH8R

Take it to the dealer.

SS07

Using the info center in the cluster see if the cylinders change from 4 to 8 when it jerks around. With the transmission issues these cars are plagued with I doubt its the DOD. Take it to the dealer and if they cant duplicate the issue then get a tech to jump in the car with you and get the car to do it.

LS1 Racing

iTrader: (15)

He has a GXP, which doesn't have the DoD indicator in the DIC.

I concur, though. Take it to the dealer and give the tech or service writer a ride in the car. It may not be the trans, but it sure sounds like it is.

TheBlizzard

Just for reference, this morning I was driving up a hill in 4th gear, it was doing its normal bouncing all over thing. So I put it in manual mode and downshift into 3rd gear to see if it would go away. Well it did, but then under a heavy load the car would SHUTTER really bad like I was stopping with warped rotors!

I think the trans is toast.

SS07

Oh sorry I assumed you had an Impala. You know I dont think your transmission is toast. I remember my 97 Grand Prix GTP used to do this when climing a hill and if i gave it enough gas to downshift it went away. I cant remember exactly what the issue was but many drivers complained of the same issue. I think it may have been a torque converter issue. Either way have the dealership drive it.

LS1 Racing

iTrader: (15)

It's the trans. I was 80% certain when you posted, but that shudder is a dead giveaway.

I added you to the list on the trans problem sticky thread.

TheBlizzard

Great

I am going to bring it in next week, hopefully with those symptoms they will just warranty it and replace the transmission without too much hassle.

TheBlizzard

Car is going to the dealer tomorrow morning; is there anything I should know about dealing with them before I go with this car?

I only have a warranty until June 2012 so if the transmission is the problem I don't want them dicking me around and not wanting to fix anything.

TheBlizzard

Took car to the dealer today and they drove the car with me and were able to re-create the shuttering issue at low rpms in 4th gear while accelerating.

I leave the car there so they can diagnose it further, the guy just called me and said the car is throwing P0102 code, which is low mass airflow sensor frequency. They said I have to get that replaced before they can do any further diagnosing.

Are they dicking me around so they don't have to work on the tranny? Or could a fault MAF cause the shuttering under a heavy load like they said?

LS1 Racing

iTrader: (15)

DTCs can cause all sorts of weird behavior, and while I don't think it's the cause of your transmission shudders, the dealer is correct in wanting to address it first. You just never know with these cars.

Are they going to replace the MAF?

TheBlizzard

No, my dad owns a mechanic shop so obviously I can get the parts for a 1/3 of the cost of a dealership. They wanted 220 dollars for an AC Delco MAF Sensor, while I got the same exact sensor through parts direct for 77 dollars our cost.

It should be here in the morning, I will throw that in and see if it fixes the problem. If not I will be bringing it back there for further testing.

For reference the tech took the car for a drive and with his scanner he was able to see the torque converted unlocking and locking just fine, all other functions were fine as well. His theory is that its the 4th gear end clutches if it is not the mass air flow sensor.

The only thing I am worried about is that it did it in 3rd gear while in manual mode too? So I told him there is more to it than just 4th gear.

I guess I will see what happens.

TheBlizzard

Put the new AC Delco mass air flow sensor in the car today and cleared the low and high frequency codes. Took the car for a drive and it did the same thing under a load at 1500 rpms in 4th gear.

I put my Solus scanner on the car and went for a ride and the hz for the maf seemed fine, the transmission data was all fine, the TCC brake switch works and the torque converter is unlocking and locking like its supposed to.

So I got to leave the shop and go home, the trans temp is at like 190 degrees because I was just beating on it a bit and riding trans on the brake for testing. I go to take off from a stop light and it shifts from 1st to 2nd just fine and then just slams into 3rd and 4rd. From a 40mph role if I kicked it down it would just shutter and slam into gear. In manual mode when I downshifted it felt like someone just slammed on the brakes super hard.

Even though my appointment is tomorrow I brought it right to the dealership and dropped it off.

Seriously WTF?

TheBlizzard

Shop just called, they won't cover the transmission under warranty because some dumbfuck did work to it prior to me owning it and it was not done at a dealership under warranty. An aftermarket torque converter was installed and there was a clamp put on the valve body.

The techs said there was a lot of metal on the magnet and there was other matter in the pan from the torque converter. The fluid was fine but I am assuming the person before me had it flushed and sent it to auction, once it got all dirty again it started acting up.

So now I am stuck with probably getting a new transmission I guess, I have only had the car for a few weeks so I am going to seek action from the dealer I bought it from, but who knows, he will probably be a scum bag and not do anything about it.