BMW 318i n43 engine misfire on cylinder 3. I Replaced all the usual stuff, coils, spark plugs and fuel injector, however none of it worked. The engine is chuffing heavily and if u look closely u can see the fuel injector seems to have Exaust fumes coming out of it (at least that’s what it smells like). The old spark plugs seems to be very sooty and 2 of them in 3 and 4 were oily. I’m not sure what the issue is but it is constantly misfiring and everything I’ve tried seems not to work if u have any advice please let me know.

Morning Arun 

Welcome to the Forum

I would start with a careful check of the work you have done, there should be absolutely NO leaks around the injectors or plugs so clearly your injector is either not seated correctly or the O ring seal is damaged. The spark plugs on the N43 are at an odd angle and require a special articulated tool to insert/remove them correctly. If the plugs have been cross threaded, you have a real problem. Oil in the bores could be due to hardened valve stem seals you can get a oil additive which may help but remember it helps not fixes the issue.

You don't say how many miles the car has covered or whether the timing chain has been serviced?

Dave