If I remember right on the E model and c-15's 1 & 2, 3 & 4 ,5 & 6 share a ground. A shorted injector will cause problems, it is over fueling on 1 hence the smoke and knock. Ohm the coils on 1-3 and you should find it. If in doubt swap 1 & 6 and see if it moves... Login to read more.