Originally Posted by VascoS
Hi fred. Mine is also a 2007 with the altitude fix. I dont run a PCIII, I have considered it a while ago but it was too expensive (here in Europe at least..), I didn't want any performance improvement only a fix to the lean surge. This summer I got that O2 sensor plug and yes it's basically a plug with two resistors, but it did make a very significant improvement!! if you disconnect the sensor, the bike will give a error because it cannot read any value, mind you the ECU doesn't connect with the sensor in any tecno-USB-like system! it merely reads resistance values which is what the O2 sensor outputs. With the plug the bike doesn't give you the error because it can now read something, only catch is the reading for the sensor is always the same, the ECU is sufficiently idiot not to understand something is out of the ordinary... :-)
What I was told from a friend that recommended it to me, is that the plug resistance values "fool" the ECU in delivering more fuel to the engine in a closed throttle. This has the huge advantage that when opening the throttle the bike will now be much smoother, because there is not an abrupt fuel flow increase. You also notice the bike has less engine braking. In my case it also improved fuel mileage slightly!
It's cheap, so no big risk in trying. But I cannot say how it will work with a PCIII.
Yes that lean surge is one of the issues I'd like to fix, it is still there but not as bad with the PCIII. It is interesting that on the Dynojet website they have a map specifically for the euro version with O2 plug and O2 sensor disconnected, the other maps do not mention O2 plug at all but do mention disconnected O2 sensor. I may try the euro map too.
That era Yamaha seemed to really not pay a lot of attention to ECU and software very much. I have had several of their bikes 06-08 and the fuel mapping was not so good. Motors themselves (the metal bits) are brilliant. Also were some final assembly issues but that was not design per se. The altitude problem drove me crazy but they eventually fixed it. Maybe an issue WRT labor vs too many varying emissions regs worldwide who knows.
Thanks for the info.