So back in December I'm up in Nevada visiting a friend, i filled up 2 days prior and it had been about 4-5 miles, i let her borrow my car to run to the gas station to buy some stuff. She comes back with this horrible look on her face and tells me that my car is making horrible sounds. This is my first forced induction car so I'm shaky at best. In the end, the final question, could bad gas sound like the worst knock ever in these cars? Even at idle? Or am i looking at mechanical failures? When i was running it to try and figure out what was going in, it threw a giant cloud of black/dark gray smoke and stalled.