Throttle position sensor

Araitim · Sep 16, 2018

appliance821 said:
Ducati engineers and technicians, or after market part technicians?

I see your point but the ducati techs and big companies have laws and regulations to follow. Tuners do not. Their concern is performance TDI engine health ratio. If that weren't the case then there would be no aftermarket for exhaust, tuning, perfor.ance ecu's. Exhaust catalysts, etc etc. Not everything is set optimal from the factory hence the well known hypermotard engine surge due to lean condition .

appliance821 · Sep 16, 2018

Araitim said:
I see your point but the ducati techs and big companies have laws and regulations to follow. Tuners do not. Their concern is performance TDI engine health ratio. If that weren't the case then there would be no aftermarket for exhaust, tuning, perfor.ance ecu's. Exhaust catalysts, etc etc. Not everything is set optimal from the factory hence the well known hypermotard engine surge due to lean condition .

True - but even without the lean fuel requirements the closed loop is doing important work in adapting the fuel air mixture to the environment. This is a problem for aftermarket stuff because as they change fueling based mainly on attaining smooth performance, the closed loop will keep adapting and creating some lean surge. It is in their self interest to just bung the hole. It seems though, that rapidbike is more sophisticated in how it handles this.

I think the important thing is that the bike isn't left "guessing" due to the removal of the O2 sensor. An arbitrarily rich AFM could do damage to the molecularly thin cylinder lining/oil film interface. A controlled richening, based on o2 readings, probably wouldn't.

gatdammit · Sep 17, 2018

A tuner built a limited set of custom downpipes for my 06 Acura TL, a car with a notoriously secure ECU. The work around for the dirtier air triggering CEL's was lengthened O2 bungs that pulled the sensors out of the exhaust stream just enough to keep the ECU happy. Wonder why I don't see that for Rexxer and other mappers.

ferdi · Sep 17, 2018

gatdammit said:
A tuner built a limited set of custom downpipes for my 06 Acura TL, a car with a notoriously secure ECU. The work around for the dirtier air triggering CEL's was lengthened O2 bungs that pulled the sensors out of the exhaust stream just enough to keep the ECU happy. Wonder why I don't see that for Rexxer and other mappers.

Rexxer already has mappings with disabled o2sensors in ECU (without engine light), for 821 and 939.
There is no need to put them on other places in exhaust system.

Relax · Apr 23, 2019

OP, did replacing the O2 sensors solve your problem?

Araitim · Apr 23, 2019

Relax said:
OP, did replacing the O2 sensors solve your problem?

There were some wires pinched within the wiring harness. I never replaced the sensors. I unplugged them for Andrew months and the bike rode fine. But when you come to a stop the motor hunt before it settled. I recently plugged them back in and the hunting went away. It all feels fine now.

Relax · Apr 23, 2019

appliance821 said:
So your saying the internal maps operate in a vacuum. How does the bike know if it starting at sea level on a warm day, or high on a cold mountain. It no longer has air/fuel info to adjust, based on the map, what it's pumping into the cylinders. What happens over time to the cylinder walls, what kind of stress is being placed on the motor?

So how do the fuel injection maps work on models that never came with O2 sensors?

thebamber78 · May 11, 2021

Thank goodness I found this thread! 20k miles on a Hyperstrada 939, Rapid Bike Evo fitted, and still the annoying engine surge around 5,500rpm. Read this, disconnected the O2 sensors and hey presto it’s fixed. Also turned off the RB auto tune, always found that to be **** anyway. Just need a dyno to setup a good RB map now, as mine is just a bit of guess work in truth. I can live with the engine light on, the RB made the engine light come on/off more times than a set of twinkling Christmas lights! If anyone has a good RB map (I know its bike specific, but it would give me a good starting point) please let me know, thanks.

Araitim · May 11, 2021

thebamber78 said:
Thank goodness I found this thread! 20k miles on a Hyperstrada 939, Rapid Bike Evo fitted, and still the annoying engine surge around 5,500rpm. Read this, disconnected the O2 sensors and hey presto it’s fixed. Also turned off the RB auto tune, always found that to be **** anyway. Just need a dyno to setup a good RB map now, as mine is just a bit of guess work in truth. I can live with the engine light on, the RB made the engine light come on/off more times than a set of twinkling Christmas lights! If anyone has a good RB map (I know its bike specific, but it would give me a good starting point) please let me know, thanks.

Look at "adventures in hypermotard tuning" on this forum. I know it's for a 821 and yours is 939 but it's a great start. Input all the setting(read through till the end. He made some changes) then (if I were you) I would turn on auto tune but set the perrameters to a very small window of adjustability then go back in after a little while and see how the auto tune is trying to adjust. That's how I would do it if I had the 939 untill I could go get it Dyno tuned. You can always go in and do what I mentioned and if it acts funky go back and change it.

Throttle position sensor

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