I was at a PCA DE at Gingerman Raceway this past weekend, where one of participants with a 2007 CS with 90K miles on clock had a bit of an "interesting" experience. First issue, which I assume was minor, was he had the notorious cloud of white smoke upon start-up for the 2nd or 3rd session of the day. I explained to him about the AOS issues, that perhaps it was a 1-time event, but if it recurred he may have to replace the AOS. Thankfully the problem did not recur. But what did happen was this: near the end of his next session coming down the front straight he heard a strange grinding noise and the oil low pressure indicator came on, so he coasted off track and killed the ignition. He sat for 10 seconds or so, and then tried to restart the engine, and a huge ball of flame came out the tail pipe. To those of us watching from the paddock area it looked like a flame thrower - a good 2 feet of flame I would guess. Needless to say he didn't try starting it any more and, was towed in. Later as the car sat in the paddock he checked the oil level and it reported it to be OK. Any idea as to what may have happened? Could the earlier issue of the white puff of smoke somehow been a factor, or was that merely coincidence? It seems to me that such a huge ball of flame would most likely be unburned gas, not oil. Could an injector have failed and started squirting gas into the cylinder at the wrong time, like on the exhaust stroke?