PC III Mapping

[S76]

I'd like to share some Gen 2 PC III map data to anyone that still has one of these. When I installed my PC III years ago the main reason was to eliminate the mid corner Hesitation that plagues these bikes and many others. It did not help. Computer calculated fuel consumption went from 43 ish to 38. Spark plugs that used to come out spotless were now tan.

A friend had a TL with the same problem. He took it to a Dyno guy that remapped his PCIII and the bike ran perfect. When I looked at his program I could see what the difference was. The guy plugged in a value of 15 for the 0 throttle position from 2000 RPM up to 6000 RPM. By putting these values in the fuel is not completely shut off during decell entering a corner, and therefore the hesitation is eliminated.

After doing this and fixing the hesitation, I then remapped the rest of the PCIII fuel table to all zeros, or empty data points, and plugged the O2 sensor back in. Fuel mileage is back, plugs are spotless and power is a tad better as the PC maps were rich.A PC III cannot fuel the engine as efficiently as an active O2 sensor. But being able to change the zero throttle position fuel map is the real value.

I hope this zero map info hasn't been posted before.

 

[Fred W]

Nice detective work, Bob. And really easy to replicate for anyone that wants to do that.

I can't speak to the 2nd Gen fuel map, but the factory 1st Gen mapping was also significantly lean in the 2500 - 4500 rpm range, especially when running on the O2 sensor. Just cruising along at a steady 3500 rpm the bike would have enough lean surging to be bothersome. Not everyone feels lean surging, or is bothered by it. It bothers me. That was my reason for getting a PCIII on my '05. The throttle transitions were not as bad as what many '06 - '07 owners experienced, though what it did have also improved using your method.

I'm happy to report that sometime between 2005 and 2014 Yamaha figured out how to produce proper fueling while still meeting EPA emissions as my 2014 does not have lean surging at cruise. It does still have fueling cut on over run, like most other FI bike engines, but that is quite tolerable, especially with Fly By Wire and Touring (precision) drive mode.

In the FWIW department - a tan or light gray colored deposit on the spark plug tip is an indication that the fueling is optimum. While dark colored deposits show a rich running condition, a totally bare tip (given enough run time) indicates the cylinder is running too lean. YMMV.

Edit to add reference: How to read a spark plug