XIED and gas mileage
Road Warrior
Joined: Apr 2009
Posts: 1,360
Likes: 4
From what I've read in tuning guides, you can use the stock O2 sensor with accuracy for an AFR range of 14.2 to 14.72 or Lambda 0.970 to 1.003 which encompasses the cruising operating ranges. Trying to use the O2 sensor outside that range impacts the sensor long term reliability. In theory you can, with some inaccurately, use them from AFR 11.74 to 17.62. I don't think anyone pushes the sensors that far.
Broadband sensors can provide better accuracy over a larger AFR range. Whether the sensors provide good enough accuracy in the HD environment or if they make a difference on the street is subject of many often heated debates. True wideband O2 sensors are accurate over a larger range, but not considered economically feasible for street use.
When stock bikes run closed loop, the ECU sets fuel based on a number of tables and algorithms and then uses the O2 sensors as feedback to adjust the tables to, in the end, get the desired AFR. When running open loop, the ECU simply sets fuel based on the tables and algorithms (and other operating conditions) without O2 sensor feedback. The kind of adjustments the ECU needed to make to maintain cruise AFR, are carried over to the open loop.
Broadband sensors can provide better accuracy over a larger AFR range. Whether the sensors provide good enough accuracy in the HD environment or if they make a difference on the street is subject of many often heated debates. True wideband O2 sensors are accurate over a larger range, but not considered economically feasible for street use.
When stock bikes run closed loop, the ECU sets fuel based on a number of tables and algorithms and then uses the O2 sensors as feedback to adjust the tables to, in the end, get the desired AFR. When running open loop, the ECU simply sets fuel based on the tables and algorithms (and other operating conditions) without O2 sensor feedback. The kind of adjustments the ECU needed to make to maintain cruise AFR, are carried over to the open loop.
Last edited by ColdCase; Feb 18, 2011 at 02:18 PM.
Tourer
Joined: May 2007
Posts: 484
Likes: 2
From: Alabama
From what I've read in tuning guides, you can use the stock O2 sensor with accuracy for an AFR range of 14.2 to 14.72 or Lambda 0.970 to 1.003 which encompasses the cruising operating ranges. Trying to use the O2 sensor outside that range impacts the sensor long term reliability. In theory you can, with some inaccurately, use them from AFR 11.74 to 17.62. I don't think anyone pushes the sensors that far.
Broadband sensors can provide better accuracy over a larger AFR range. Whether the sensors provide good enough accuracy in the HD environment or if they make a difference on the street is subject of many often heated debates. True wideband O2 sensors are accurate over a larger range, but not considered economically feasible for street use.
When stock bikes run closed loop, the ECU sets fuel based on a number of tables and algorithms and then uses the O2 sensors as feedback to adjust the tables to, in the end, get the desired AFR. When running open loop, the ECU simply sets fuel based on the tables and algorithms (and other operating conditions) without O2 sensor feedback. The kind of adjustments the ECU needed to make to maintain cruise AFR, are carried over to the open loop.
Broadband sensors can provide better accuracy over a larger AFR range. Whether the sensors provide good enough accuracy in the HD environment or if they make a difference on the street is subject of many often heated debates. True wideband O2 sensors are accurate over a larger range, but not considered economically feasible for street use.
When stock bikes run closed loop, the ECU sets fuel based on a number of tables and algorithms and then uses the O2 sensors as feedback to adjust the tables to, in the end, get the desired AFR. When running open loop, the ECU simply sets fuel based on the tables and algorithms (and other operating conditions) without O2 sensor feedback. The kind of adjustments the ECU needed to make to maintain cruise AFR, are carried over to the open loop.
So you mean that the fuel mixture will only be richer using the xied's when running down the highway at a constant steady speed. What would the fuel mixture be like when running the Dragon, where you would be accelerating and dropping speed from say 30 to 60 mph thru the twisty's?? Would the o2 sensors be adjusting then or would that be out of the range where the ECM would be accepting feedback from the o2's??
Road Warrior
Joined: Apr 2009
Posts: 1,360
Likes: 4
Through much of the twisties, the ECU makes an intelligent guess on the amout of fuel that provides the desired AFR (or lambda). The AFR will vary from say 13.4 to 14.7, or no fuel. The ECU sets the injectors and timing to whatever the built in tables call for based on RPM, MAP, MPH, temperature, throttle position, ION sensor, dynamics... a bunch of parameters but not the O2 sensor (the AFR target is outside the O2 sensor's most accurate range). This is the so called ECU map. Because the ECU carries over the fuel adjustments it made to get the cruising AFR right, the Xieds will have some effect all around that results in a richer mix that should improve seat of the pants performance and throttle response. The stock ECU runs things a bit lean all around, and Xied will trick the ECU into running the bike a bit richer, regardless if the O2 sensors are in use or not. The relationships are complex, however.
The only way to know what the actual AFR is for your bike with accuracy is on a dyno with their exhaust sniffers.
The stock map provides the best drivability, power, mpg given EPA limitations and production variances. You can use a tuner tool or hire a tuning pro to customize the map parameters to your bike and riding style. it seems to wake the bike up a bit more than an Xied, but the Xied may be good enough to be riding with smiles and be picking bugs out of your teeth at the end of the day.
The only way to know what the actual AFR is for your bike with accuracy is on a dyno with their exhaust sniffers.
The stock map provides the best drivability, power, mpg given EPA limitations and production variances. You can use a tuner tool or hire a tuning pro to customize the map parameters to your bike and riding style. it seems to wake the bike up a bit more than an Xied, but the Xied may be good enough to be riding with smiles and be picking bugs out of your teeth at the end of the day.
Last edited by ColdCase; Feb 19, 2011 at 10:27 AM.
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