sounds like a cylinder/valve problem of sorts...

:edit

but that is just my guess...by you saying it sparked...

This post was edited by chewbacha on Nov 8 2013 09:18pm

partly to do with my assumtion
when turning it over, gas got into the cylinders, but the plugs decided to take a shit ( maybe only 1-2 of them ) but there was enough spark in the rest to ignite some of the fuel from the other cylinders, and in its slow roll back out of the combustion stroke the exhaust valves finially opened causing a bang

ive only ever really seen it happen with dirt bikes n shit, but heh. if his car runs fine now, fawk it

This post was edited by IB0T on Nov 9 2013 08:07am

yeah it starts up fine now perfectly

let it run for 15 minutes when i got home last night, nothing happened