Engine Won't Shut Off
This morning I experienced the most bizarre problem I have ever had with a vehicle. I started my '10 Cobalt LS1 engine (cold, high 60s) and noticed that the running engine was making a loud clicking sound. After about 20 seconds of running the engine with the clicking noise I decided to turn the ignition off. However the engine did not stop, and remained on for about 5 minutes. This problem came a week after I took it to the dealer for a CEL problem, the diagnosis was bad Knock Sensor (of which I did not pay $400 to replace with included fuel injector cleaning service). To resolve the CEL myself, I decided to use Lucas Fuel Injector cleaner in a tank of 91 premium gasoline to see if a cleaning was actually needed. The vehicle has gone about half a tank without any issues, until today.
Back to the engine problem. With the ignition in the OFF position, the car sounded like it was dieseling (although not sure how since it was a cold engine, and also because its Fuel Injected). I was able to turn the ingition switch to ON (not START) and actually REV the engine on all firing cylinders. Turning it back to the OFF position prevented me from rev'ing the engine, and it slowed the rate of turn of the engine as well. After about 2-3 minutes the engine started turning over more slowly, about 1-2 revolutions per second, and then eventually died, as if the battery was dead.
I opened the front hood during this time and the engine was smoking (small, light plumes), and it smelled of heavy fuel. My guess is the heavy fuel smell was from the engine turning over without actually firing. I removed the 50A Fuse from the rear (this keeps the car from starting), came back about an hour later, plugged the 50A fuse back in and started the vehicle. I drove it for about 10 minutes on the highway with no noticeable issues.
I also have had 4 recalls serviced at this same dealership (3 last year, 1 this year). This includes the infamous ignition switch one.