I wouldn't be posting if I hadn't spent more than a month trying to figure this one out already.

When I start my car (B18C1 - 310cc - emanage - LC-1 - BKR7ES) cold, I run somewhere in the 16-17AFR area during the warmup (1-3 minutes). After that it settles around 14.7. If I just start it up and drive, it's fine, never a CEL.

If I start it up and leave it sitting at idle to warm up, I get (sometimes) the misfire codes.

My question is: What chain of events /sensors cause the P0300 codes?

I've tried a few different plugs and gaps. Doesn't seem to matter.
I can add or remove fuel with the MAP adjustment, or the injector duty.
I can pull or add timing with the ignition map, but the dizzy timing is dead on.

 

when the motor is cold the afr ratio should be a little richer than stoicmetric. you have it way too lean and causing a lean misfire. You should try to get it to somewhere around 13.5 when started and have it gradually lean out to around 14.7 when warm.

 

Perfect response. Much appreciated.
I thought that during warmup it was supposed to be rich.
It was so lean and gradually richened up, that I thought it was a normal part of the warmup cycle.
I bet that is the root of the p0171 I get every once in a while.