Hi Guys,

I am new to the forum. I have had my Montie Carlo for a few months now (11) (2006 3.5L with 140,000) and I love it! My problem is this. Randomly, the car will just start shifting HARD (1-2 shift) and the check engine light will come on. Then it will stop and the light will go off after another 50-100 miles.

For the life of me, I cannot figure out what is happening. The car has had a full tune up, new O2 sensors and cam positioning sensor, new throttle body. I don't get it. I have the trans checked and everything came out fine. I even had the ECO re-flashed.

Any help would be very much appreciated and I look forward to hanging out here (I plan to get an SS eventually)

 

What codes is the cel pulling up?

 

It threw a code saying the O2 sensor was bad and also the the cam positioning sensor was bad. I replaced those and it still continues to shift hard for awhile and then will be normal for awhile, and then start shifting hard again.

 

Hmm, you sure you changed the correct O2 Sensor and installed correctly? Could be that the replaced parts were defective. Rare case but it happens from time to time.

Does it still throw a cel after those parts were replaced?