In defense of George...... since he is out of town this week end. George has
his EE degree and is well aware of exactly what he is doing.
As far as differences in the 93 and 94 ecu's, Yamaha changed the
"programming" of them between 93 and 94 to enrichen the decel circuit. Some
riders under some conditions were able to create a condition that caused the
engine to stall during decel. To address the issue, they adopted the european
ECU for 94 US models, and, replaced some 93 ECUs with 94's if a customer had
a problem with stalling. The 93 ECU is no longer available. The part number
automatically supercedes to the 94 part number. The 93 ECU upon decel stops
fuel flow through the injector, until the RPMs decrease to a predetermined
level (providing the TPS is still saying the throttle is shut down). My
recollection of their explanation was the 94 ECU restores fuel flow at a
higher RPM than the 93, to address this throttle off stalling issue some
people had. As an interesting story, I let a friend of mine who was service
manager at the local dealer ride my GTS, which he had never done before. He
came back and said it stalled three times on him. It had never stalled on me,
so it must have been his style that caused it to happen. It seems logical to
this meck a neck that if you richen a decel circuit, you are going to
sacrifice fuel mileage. George was attempting to address the low speed surge
issue by installing the 94 ECU. We saw his post of the result.
As far as speaking with the EE that designed the ECU, one would have to
learn Japanese and book that two week vacation to Japan, just to begin to
make that happen. However, I am guessing, plan day trips while you are there,
they probably consider that information proprietary, and, would not
understand a word you said, they would just politely smile.
