[FRSBRZGT86FAN]

Originally Posted by mdm

Without researching it any more, I'd theorize the following scenario.

During Several unsuccessful attempts at push-start the air-fuel mixture flows through the engine and fuel is collected in cold cat. When the engine ultimately starts, the cat heats up, and suddenly you have a significant amount of fuel in the presence of very hot catalysts, and things get nasty.

One thing that my brilliant theory does not explain, is why things would be any different if a few unsuccessful starts using the starter are followed by successful start.

That literally is not how it works, the cat stays cold it takes quite some time for it to warm up, so much so any unburnt fuel will ignite in the exhaust regardless by that time or just get sent into the atmosphere, if it does nothing dangerous will happen it's contained. People are actively creating tunes to do this by retarding ignition timing off throttle to get there exhausts to crackle and pop.