The science of O2 sensors as I understand it FWIW.
From what I have gleaned on this subject from my car tuning days is that on our European specification bikes, is that a 'closed loop clean air' system is used to read the Oxygen sensor (lambda) located in the exhaust pipe, and under certain conditions, temporarily change the air/fuel ratio to stoichiometric
” value of 14.7:1. This is to provide a chemically efficient burn for low rpm cruising and to aid emissions.
The closed loop circuit has a very limited operating range, which is only in effect while holding a steady speed at certain rpm and throttle positions. This ratio, while good for the environment, creates flat spots and a lack of torque that is required in certain instances, even in the low rpm area.
The Oxygen sensor can be disconnected but this will trip the F.I. warning light on the bikes dash.
You can either, by using Dynojet jet Oxygen sensor eliminator ~ Ģ20.00 or make your own Oxygen sensor eliminators by installing 330 ohm - ― Watt resister across the heater leads to the OEM sensor to stop the FI warning light illuminating / giving an error.
Unfortunately some Ecu's aren't fooled by the O2-eliminator mod and when it enters closed loop mode, it tries to adjust the air/fuel ratio. Unfortunately, any adjustments the ECU makes won't register because the O2-eliminators are sending a constant signal to the computer. So the ECU continues to adjust the air/fuel mixture in a vain attempt to reach stoichiometric
ratio and it eventually leans out the air/fuel mixture so much that the engine loses a ton of power. Then when you twist the throttle a bit, the ECU leaves closed loop mode and goes back to the default map. The engine suddenly makes power again and the bike lurches violently forward.
Ironically, the O2-eliminators are suppose to make the ECU think everything as just fine when it enters closed loop mode, but it instead has cause some bikes to surge severely.
The trick around this is to prevent the bike from entering closed loop mode. On some bikes you can fool the ECU not to go into closed loop mode by starting the bike before it has completed its FI / ECU boot up process
If you start the bike before the ECU finishes its boot up cycle, then it won't go into closed loop later. My guess is that by starting the bike before the ECU boots up causes an error in the ECU. To protect the bike, the ECU loads the default map and sticks with it. So, once you turn the ignition on, start your bike immediately and you shouldn't have any more surging issues. (Likewise, there's no reason this wouldn't work for bikes without O2-eliminators either).
This is a suggested start up procedure that could work:
1) Turn ON ignition.
2) Put the bike into neutral.
3) Wait for the fuel pump to prime the fuel system etc.
4) Then Switch OFF the ignition.
5) Push and HOLD on the starter button with right thumb,
6) With left hand, turn ON ignition, (Bike starts)
7) release starter button.
This seems to take the O2 sensor out of the closed loop mode and the bike then runs in open loop all the time.
Sorry if this is above some peoples heads but iv,e tried to put into as much plain Scots as I can
Have fun experimenting.