Re: Question for the pros! 2003 4 stroke 150 Yamaha
no way around it you MUST have the correct diagostic tools AND know what and why they appear on the screen
you can buy the kit for 300 dollars.
if your going to monkey with stuff ya gotta buy the bananas.
you simply gotta watch what the ISC,MAP and TPS sensors are doing as well as injector on time and ign timing while its trying to die.
the ECU is going to attempt to make it idle at about 650, it mainly relies on the ISC valve to vary the intake air. the TPS tells the ECU that the throttles in a certain position and the map sensor gives it engine load.
from there the ECU can make fuel injector on time vary and ign timing vary as well as add or subtrct intake air vi the ISC valve.
my guess is the link and sync is off or its set like the factory settings.
what I typically do is open the throttle shutters slightly,after syncing them, and watch the ISC, when it hits about 40% stop and reset the TPS to about .7.
this gives the ISC a faster reaction time and more range.
but this can only be done after verifying nothig is broke.
we find it gets rid of that annoying off idle stumble and die.
