Guys can someone please explain the benefit of removing the O2/lambda sensor? My understanding (please correct me here if wrong) is that it's only used while on closed loop. So raising the idle with the likes of tuneECU or a manual idle speed adjuster should take the thing out of the equation anyway?
i could be wrong, but i think the idle is controlled by the engine temperature sensor not the lambda in the exhaust, i believe the engine is closed loop up until a certain point (5-6000 RPM at a guess). If you take it out the bike will run optimum fueling for performance with out the probe but if you have a couple of thousand meters height variation(riding to the alps maybe?) it could affect the running. I'm sure some one more knowledgeable will be along shortly to confirm that im wrong
Generally the 02 sensor is used at lighter throttles and when cruising. This is more for fuel consumption and emissions rather than performance. For higher loads and wide open throttle its not used. Turning it off allows you to have more precise control over the fueling thats not going to be messed around with by the ECU. So you can run a map that has a better throttle response than one that is constantly hunting around for economy/emissions. Standard narrow band lamda sensors only work around a very small range of Air Fuel ratios. Typically about 14.7 you probably want to be a bit richer than this for max power but 14.7 is perfect for best combustion and thus emissions. Hope this helps. PS You can get wide band lamda sensors and these are more useful for performance tuning.
Bazza, so the use of the O2 sensor is dictated by both engine RPM and throttle position? I've got a short action throttle and TOR exhaust fitted (mapped accordingly) but its snatchy in the fore mentioned situations. Do you believe removal of the O2 sensor may fix this? Cheers guys
The Lambda sensor basically monitors the fuel-air mix (actually the unburnt oxygen compared to the atmosphere) and the ECU uses it (and other sensors) to determine whether the engine is running lean or rich so the ECU can change the fuel-air mix appropriately. It ignores the sensor when the revs are high or the throttle is wide open to prevent the chance of a misfire and possible engine damage. Raising the idle speed is unlikely to get the ECU running on open-loop. It's basically an emissions control device and I beleive you can remove it as long as you tell the ECU to ignore the Lambda sensor (via TuneECU) so that it always runs on open-loop.
I fitted an Akra exhaust and custom map but found the engine snatchy at 5k RPM. Took it in to T3 who did the map and he disabled the lambda sensor and it fixed the problem.
