Consistent misfiring at idle with cyl number 1

[128keaton]

Hey all, working on a 1987 325e to I swap. I put the engine together, redid the heads, refreshed valve seals, etc, and I cannot get this thing to stop misfiring on cylinder 1. I can remove the spark plug wire for number 1 and not effect the running condition. Does not appear to be an ignition problem since rotor, cap, wires, plugs are all brand new and I hear it arcing when I pull the wire off and ground it. Compression test shows 150PSI+, valves seem to be fine. It cranks really easily and runs easily, has great vacuum (no leaks, I promise!) but at idle the engine shakes due to the misfire. When revved up, it seems to be firing fine, but I haven't had a chance to take it down the road yet. O2 sensor is hooked up. Really stumped here, nothing _should_ be stopping it from running fine. Only thing I am unsure about is one of the wires in the glovebox but i'm fairly certain it is for A/C activation. The plug on cyl 1, when removed, doesn't seem excessively rich or lean, not covered in gas or oil. If it wasn't firing period, I'd think it would smell like gas.

The harness and engine is out of an 87 325i so nothing crazy going on.

Hoping its not like a degree off time, but I don't think it would run as well as it seems to be minus the misfiring

[MrBurgundy]

Might be an injector issue. Could be the injector itself, or the C101 connector under the intake has some corrosion, or connectivity issues to the fuel injector harness.

Use a stethoscope, or a screwdriver and listen for the audible clicking an injector makes as it opens and closes.

[D3R3K]

Have you tried swapping the spark plug from Home to Forum and see if it still missfires? also would be a good idea to check leak down, compression can show good numbers but you could have a nick in the valve seat that leakdown will find, you could also try swapping fuel injectors from 1 to 2 aswell. hops this helps!!