"JC,That is the problem......the ECU does NOT go to any 'default' mode since it does NOT think it has a problem.
To fix the problem it's going to take a dedicated technician with some good data aquisition tools to actually 'capture'
a failure.
It's already been proven that replacing the ECU will not fix it (Gumba has done that twice) and a PCIII won't fix the
problem but it IS more fun to ride and messing with the CO settings blindly (without having a 3-gas EGA attached via
RivNuts or something similar in the exhause headers) will do nothing. To set the CO% using the one byte register in the
diagnostic mode, you need to have the EGA attached. You are using the -128-+128 value in that CO register for each
cylinder to compensate for Injector patterns, fuel pressure, intake tract casting irregularities, gasket interference and exhaust system
pulses fed back to the intake.
Mick"
Hi Mick...you sound lots more experienced than I and I promise to never ask this again...but doesn't disabling the critical sensor(s) such as O2 or Intake manifold pressure force the ECU into a default basemap or "Able" running condition as explained in the SM and generate an error code?...Wouldn't forcing a default mode and error code allow the basemap to control the engine, and wouldn't that temporarily eliminate some of the issues and errors associated with closed-loop operation as some have experienced if it's defective?...If the closed-loop operation is worse, then that can be addressed with Yamaha if they can substantiate and/or admit it's errors...I'l bet they never do, even if identified, and fix it next model cycle Worldwide...I've asked this twice before elsewhere but got no response...please clarify this if you or others can and I'll hide in the woods and watch.
Gary in Fairbanks
I completely agree with Mick here. This is a fix that will take some doing on the part of Yamaha. It is going to be way beyond backyard tuner bandaids, or even aftermarket folks like Dynojet. Think about it. The problem arises under very specific conditions of altitude and throttle application. Unless you can come up with a fix that only affects those combinations of inputs, you are changing the entire operational spectrum of the bike just to cover the small part of it where it is malfunctioning. The fact that the problems came up under such limited circumstances is what led me to believe initially it was bad ECU programming. As I have said before, it smells like something related to factory programing around deleting sensor(s), meeting tougher emissions, semi-automaitc gearbox, and frankly: carelessness. It is a corner of the input matrix not envisioned by the programmers, who as we all know are poorly fed slaves locked in boxes in the basement of the Yamaha factory.
Now keep in mind any fix Yamaha does make (if they ever do) still needs to meet a) US emissions, and b ) Euro emissions, c) retain drivability and d) be cost effective you can see the difficulty. In other words, the fix they come up with needs to affect only the conditions of operation where the problem occurs and not mess up the rest of the operating envelope (unlike the tuner bandaids), and not require, say, replacing all the electronics on the bike.
Gary, disconnecting the O2 sensor does not throw an error (at least none was read by my delaer, and no check engine light flashes). It does default the engine to a base map, in fact this is why you need to disconnect the O2 sensor for the PCIII to work (it works off the base open-loop map adding or deleting fuel). Otherwise the ECU + O2 sensor in closed-loop mode would try to defeat the PCIII. I doubt if the engine would run at all if you disconnect the MAP sensor, it would have no way to measure air.
All of the various fixes suggested are well-meaing, but I am afraid this is way beyond the resources of anyone without the ability to read, code, test, and debug Yamaha factory ECU's & sensors, has emissions testing equipment suitable for certifying EPA and euro complianace, and can look into design specs and know what was deleted or changed from Gen I to II, and from MY 06 to MY 07.
So we wait, report things to Yamaha and NHTSA, and hope no one gets killed or hurt bad if they are caught out by this problem trying to get out of the way of an 18-wheeler (for example). In the mean time a PCIII really helps but does not eliminate the problem. The bike is enjoyable and only mildly annoying in the situtations where I ride it (wide open spaces in the mountains and little traffic). Without the PCIII it is dangerous under any circumstances.
