[Anaxagoras1986]

Does anyone know what could cause this? It is a stock 944 as far as I know. I do know the engine was rebuilt but I dont know how long ago that was. The engine runs perfectly except for when I start it, it usually back fires and grinds the starter badly...

I put 93 gas in it everytime which helps reduce this but it still does it. I tried putting a booster in it and that reduced it even more. A stock 944 NA is supposed to be able to run on normal gas right? What could be causing this?

BTW, I checked the computer with the ignition timing and it is set to stock. I tried slowing it down and it just made it worse.


Thanks for any help!