R1250 Fueling — Wideband O2 Sensors

[roger 04 rt]

Here’s some information on the R1250, which is supported by data coming from the GS-911.

 

As most know, the R1250 has three oxygen sensors: two are in the headers, one per cylinder, located ahead of the catalytic converter. Those two sensors are used for precise fueling control by the ECU. The third sensor is after the cat and will monitor to make sure the fueling is stock (or within range of stock) and that the cat is doing its job. It’s an automated environmental police officer.

 

Apparently no one has looked at the O2 sensor till this week. A new friend volunteered to run some gs-911 logs and take some pictures in preparation for an AF-XIED trial. The pre-cat O2 sensor has a new connector and five wires.

 

BREAKING NEWS
The two oxygen sensors ahead of the cat are WIDEBAND O2 SENSORS. Simply, this means BMW will be able to set a MUCH broader range of AFR targets but they will still have to satisfy the Euro 4/5 guys and keep the cat happy.

 

It also means a radically different ECU code since the Wideband O2 is programmed, controlled and monitored in a very different way.

 

IMPACT
It will take some time to develop strategies to alter via add on or to recode the ECU. And it will take time to learn how to deal with the 3rd O2 cop. And the fueling of the R1250 is probably very good as it is.

 

However since the engine has to run lean to meet the operating parameters of the catalytic converter there will be the possibility of improvement. But it will take time to know just how to achieve those goals and keep the R1250 as good as it already is.

 

As a community, we should spend some time and learn the new ECU control system rather than rush for a “fix”.

[JamesW]

Hello Roger,

That is most interesting about the use of wideband sensors ahead of the cat.  It is maybe possible for BMW to program different value AFRs maybe using some type of ECU interface equipment?  But then why on earth would there be a need to do that?  I just can't see the reason for the wideband sensors.

 

Maybe use the widebands to make the bike universal without any hardware changes for different world markets? 

[roger 04 rt]

With a Wideband O2 than can run closed loop, at any AFR, throughout the entire fueling map. They will still be constrained by the need to run at lambda=1 for most of the map to keep the air clean and the catalytic converter running efficiently, but they will be able to tune much of the rest of the map for good performance.

 

This is a good change but it makes it harder still to alter the bike’s fueling, if you're inclined to do that.  

[JamesW]

You have got to like complexity...I guess.  I'll keep my '93 R1100RSL running at 13.2:1 closed loop thank you very much.  

[roger 04 rt]

In addition to the new Wideband O2 sensors, the R1250 appears to have a throttle valve sensor (TPS) for each cylinder. I'm basing that off the realtime values being logged by a test rider.

 

What we see in the logs is: a twistgrip sensor, throttle valve sensor 1 and throttle valve sensor 2.

 

I see this as a significant enhancement to the R1250. No longer with the BMSX be "hoping" that Cylinders 1 and 2 are each opened the same amount. The ECU will know, within the accuracy of the sensor, how much each TB is open.