Difficulty accelerating, and bouncing in and out of overdrive
Recently, my 2008 G6 GT (3.5L) has started misbehaving. Sometimes, when I accelerate from a stop, the car will start to move normally, then stop responding for a few seconds. If I hit the gas pedal harder, the RPM’s don’t even rise. But either the car will start moving normally, or (if I’m not in first), it’ll downshift and everything will be fine. This is especially bad on my uphill driveway. If I take my foot off the gas entirely and then press it again, it usually accelerates normally.
Also, if I’m cruising between 35 and 60 mph (most noticeable at 40) with almost no pressure on the accelerator, it will sometimes kick in and out of overdrive every few seconds.
I last had the transmission fluid and filter changed about eight months/20,000 miles ago. The shop said it was likely the last owner had never changed the fluid; it was black, but they saw no clutch gunk nor any loose metal on the magnet. They also did my plugs and wires at the same time.
No check engine lights. What do you think is the problem? I’m guessing I could have a bad accelerator pedal or throttle position sensor, but I’m thinking the transmission is shot, unless I’m “lucky” and it’s just low on fluid somehow (no known leaks).
2008 Pontiac G6 GT convertible, 3.5L V6, 130K miles