RPM converter allows data recordings to have a reference point. Map sensor allows you to see actual engine load. The narrowband sensor needs to be used as a means of seeing if the ratio that your wide band is reading is what the engine is happy with. You need to ignore the narrowband output VALUE, and just pay attention to the AMPLITUDE of the voltage signal. A jagged voltage line tells you the engine isn't digging the current a/f ratio. Example: your engine is running at a 12:1 ratio. You look at the data log and at 12:1 the narrowband voltage output is not smooth. You can go richer or leaner and see if the amplitude gets lower. If it gets higher(more squiggles) you went the wrong way. Alot of people have dismissed narrowbands. I'm not one of them.