Did you ever have any Yosh mapping done to the stock ECU? Mine did this when the slow speed setting was too rich. Blipping the throttle at idle would make it unhappy and the revs would drop to 750 or so before it cleared out (worse as it got warmer). As I understand it, the PC2 builds off the stock ECU signals, so it has to be zeroed. Mine is much better with the PC2. It idles and pulls cleanly away from a stop. There is still some work to be done in the 3500rpm range at small throttle openings. Its not bad, but its definitely a little flat (and wierd) through there. Looking at the Dynojet 004 map, they are tweaking a good deal in that range (rich, then quickly back lean). If there is just a flat spot in the pipe design (always tradeoffs), it'll never be perfect, but we can try to make it better. I'll probably try a few things this weekend. Overall, I'm fairly happy at this point. Wish I had a dyno and a gas analyzer though;-) Again, anyone out there fiddled with combination and gotten an improved map?
