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Buell Forum » Big, Bad & Dirty (Buell XB12X Ulysses Adventure Board) » BB&D Archives » Archive through October 28, 2009 » Dual O2 Sensor Setup « Previous Next »

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Electraglider_1997
Posted on Sunday, October 25, 2009 - 11:30 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Hadn't seen any discussion on this. 2010's have two 02 sensors feeding info to the ECM for fuel management. Anybody have an idea if updating to this setup is more than 2010 pipes, 2nd sensor, and 2010 ECM? What advantage if any would this offer other than better controlled emissions? Does anybody know if low speed fueling and rideability is any smoother? It just seems in my mind that Buell should have been running 2 02's from the 2006 get-go. Rear cylinder is hotter, so fueling from O2 off the hotter pipe seems less than optimum. Wouldn't that make fueling the front cylinder always richer than the rear or does the ECM fuel mapping compensate for front injector compared to rear injector on single O2 models?
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Pkforbes87
Posted on Sunday, October 25, 2009 - 01:36 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

The rear cylinder maps are already richer to compensate for the extra heat. I would think that a dual O2 sensor setup would be ideal, but not worthwhile IMO to mod a pre-10 bike.
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Towpro
Posted on Sunday, October 25, 2009 - 03:22 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I read the ECMspy guide and it says the same thing "the rear is richer".

But a cooler cylinder (front) needs more Fuel.

And when I look at my factory maps, the front is richer then the back.
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Road_kill
Posted on Sunday, October 25, 2009 - 03:59 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I understand the engine maps are biased for richer rear cylinder operation. However, Buell added the 2010 front cylinder O2 sensor (and expense) for a reason. Better performance? Better emissions? Smoother running engine? All the above? Not sure ... but I am interested.
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Hughlysses
Posted on Sunday, October 25, 2009 - 05:23 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

My guess would be that having the single O2 sensor had to be a compromise. The engineers would have figured out the relationship between the required fueling for the rear cylinder and the front cylinder, then they'd take a signal from the O2 sensor (for the rear cylinder) and use the ECM to set front and rear fuel values according to their tests. This probably provides correct fueling for the front cylinder most of the time. Having 2, independent O2 sensors lets the ECM independently control the fuel mixture for each cylinder, which is bound to be better under at least some conditions.

BMW went through a similar phase with their opposed twins a few years back. People complained about the fueling when they first introduced fuel injection and BMW kept telling them nothing was wrong. The used a single O2 sensor for both cylinders. Finally, a few years back BMW added a second O2 sensor and a more sophisticated ECM. Supposedly the new engines ran remarkably better. IIRC Cycle World said what it amounted to was controlling the engine as if it were two independent single-cylinder engines.

It's a shame Buell added this only to have the bikes canceled 3 months later.
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Tootal
Posted on Monday, October 26, 2009 - 07:35 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

BMW also went to twin plugs although I've heard they don't fire at the same time. My experience with twin plugs is smoother idle and easier starts and better mileage. I've always thought Buell's should of had them.
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Towpro
Posted on Monday, October 26, 2009 - 09:29 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Hugh has it correct. When running in closed loop, they can now monitor both cylinders to cause it to run cleaner.
But I bet it is driven by the fact they have to meet EPA standards.
I think there was a new emissions level for 2010, and getting air cooled bikes to meet emission standards is getting harder and harder.
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Squidbuzz
Posted on Monday, October 26, 2009 - 09:54 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

And upgrading an older bike to the 2010 gear would be tough and expensive. New ECM, pipe, sensor, and wiring harness just to name a few.
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Froggy
Posted on Monday, October 26, 2009 - 11:41 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Not to mention that stuff would require 08 injectors, throttle body, crank, CPS, throttle cables, and more : )

I have heard conflicting info on wither DDFI2 supports dual 02 sensors or not.
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Skinstains
Posted on Wednesday, October 28, 2009 - 12:16 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

One o2 sensor per cylinder is the only way to ensure each is getting what it needs, they should've been there all along.
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