Your car backfires when you need a new transmission,or tune up. How do you know the difference? Simple...if your car backfires then wont start, or wont start and then backfires,you need a transmission. If it backfires, and then starts moments after, you need a tune-up. Glad to help...David
exhaust leak
You broke it.
It has either . jumped timing
Timing is off.
Valve timing off, timing chain jump.
Take it to a mechanic and you probably will get your question answered.
Either use the kickstarter, if it has one fitted, or bump start it.
First check for fire at any of the sparkplugs and if you have spark then check your fuel pressure and if its not within specs then replace the pump.
Possibly the firing order got messed up.
I have an 1986 550L and the best way to get it started is to push start it.
Check the crankshaft sensor. Also check the timing and timing belt. The backfiring indicates that the engine is firing at the wrong time.