I have a b16a2 and cylinder 2 goes rich then lean back to rich back to lean over a course of a few weeks. I shoot black smoke out of my exhaust and 1,3, and 4 plugs look normal. So far I have switched plugs, wires, cap, rotor, and injector to known good parts. I am getting 12 volts at the injector plugs. My compression came out with +/- 5-7 on all cylinders. I measured continuity from ground on injector clip to ground on ecu plug. What else can I try? What could it be? Can I switch number 2 and 3 injector plugs to see if the problem moves or is the timing slightly different? What I was thinking was maybe there is a nick in the wire on the injector clip. If it touched any ground it would stay open and cause it to run rich. If it didn't touch a ground it would cause more resistance in the wire causing it to go lean. I'm thinking of hard wiring the ground wire on that injector clip to see if it makes a difference what do you think?

Here is a picture of when it was rich:


When its lean it white and has little flakes all over it.

 

could there be a chunk of crap in the fuel rail right before it feeds the second injector?

could there be bad compression in that cylinder?

 

Could check the rail. Compression is fine 210 across +/- a few psi