Re: 2002 Yamaha OX66 225
you will need the diagnostic test lamp, an O2 sensor test harness,and the TPS test harness. you will need copies of the 3 tech bullitens out on testing/cleaning the O2 sensor. disreguard the one containing the flame test as its useless.
while doing the link and sync when the shutters are fully closed is when you set the air gap on the oil link arm, beaware that most the 3.1L motors its common to have to cut off a few threads from the arm to get the adjustment correct.
you also check/adjust the TPS while the shutters are fully closed.
always check the 5V reference for the TPS when checking the TPS.
the O2 sensor sets NO codes even if you unplug it.
if it becomes unplugged fuel is fixed rich at low speed and lean above 4000 RPM, DO NOT run above 4000 RPM.
however if its contaminted the ECU will not realize it and react to whatever its getting as a feed back voltage.
so its possible to have the ECU lean out the fuel at high speeds and burn a piston just cause the sensor was contaminated.
if the ECU does not see the engine as warmed up by feed back from the engine temp sensor it will hold timing about 5-7*BTDC so it will idle fast but timing can still advance so top speed can be reached.
so I would start with a compression and spark test then a good link and sync, check that the engines will go from code 33(engine warm up) to code 1(normal) and go from there.
when cleaning the O2 sensor mke sure which block you have, if the originals were ever replaced since about mid 03 production run the mounting gaskets changed.
if the wrong mounting gaskets are used rapid contamination and O2 sensor failure occurs.
make sure the correct draw tubes are installed, there is a tech bulliten that may cover your engines so hunt for it.
