Lambda - Measuring What Exactly
Discussion
oxygen doesn't burn... it combines with other atoms/molecules to produce energy from a chemical reaction. does the presence of oxygen in the exhaust indicate there is too much air (i.e. lean) and what about rich? as all the oxygen should be used up and unburnt fuel is sent down the exhaust.
As far as I knew lambda is the amount of unused oxygen in the exhaust gas. Thats the reason for wrong lambda readings if there is a hole in the exhaust, air is drawn in through the opening and so raising the amount of oxygen present.
The 0-1.5 is the voltage coming out of the lambda sensors as they react to the oxygen in the gas.
Hope this is a help.
The 0-1.5 is the voltage coming out of the lambda sensors as they react to the oxygen in the gas.
Hope this is a help.
jbvipercerb said:
As far as I knew lambda is the amount of unused oxygen in the exhaust gas. Thats the reason for wrong lambda readings if there is a hole in the exhaust, air is drawn in through the opening and so raising the amount of oxygen present.
The 0-1.5 is the voltage coming out of the lambda sensors as they react to the oxygen in the gas.
Hope this is a help.
The 0-1.5 is the voltage coming out of the lambda sensors as they react to the oxygen in the gas.
Hope this is a help.
So what are the readings referencing? Is it a percentage or just a reading that can be worked with when adjusting air flow throttle etc.
MB
As far as I know its the ratio of fuel to air calculated as a fraction of stiochiometric.
Ie 'exhaust ratio detected'/1:14 = lamda value.
Simple huh. Now that I've answered that for you how about helping me with my question.
What is the calculation for an adaptive value on the Cerb?
No one seems to know.
Ie 'exhaust ratio detected'/1:14 = lamda value.
Simple huh. Now that I've answered that for you how about helping me with my question.
What is the calculation for an adaptive value on the Cerb?
No one seems to know.
Don't even try to make sense of the readings a narrow-band lambda sensor gives you. The operating range of these units is only a very small percentage either side of stoich (14.7:1 AFR or lambda = 1).
For max power a Cerb probably runs around 12.5:1 which will be well outside the operating range of the narrow-band lambda sensor, so it will always read rich.
I'm not really sure why a narrow-band lambda sensor is even part of a Cerb's design unless the map that TVR originally sold it with was seriously hamstrung to *try* and provide a stoich value at MoT-able readings (idle and about 2500rpm). Surely they can't be aiming at stoich values for normal use?
The Emerald-equipped cars will have been mapped with a wide-band lambda sensor which allows an actual numerical reading to be given, not just a plus or minus a small percentage either side of stoich. The RR operator (Jools in the case of my car) will have mapped the car to a target AFR and then tweaked it a little to give the best power at each speed and load site
and then the the map will have been "fixed" or, in other words, set to ignore the output from the narrow-band lambda sensor from then on.
You can now buy cheap wide-band lambda sensors with in-line control boxes, allowing you to leave them permanently wired into your car's ECU, and with the latest version of the Emerald you can use that wide-band lambda sensor to self-map. You'll have to know what your target AFR should be at different speed and load sites, but the possibility exists now and it works very well.
I'm sure this feature is not unique to the Emerald but it's a cheap unit and has a lot of support from both enthusiasts and professionals like Jools.
For max power a Cerb probably runs around 12.5:1 which will be well outside the operating range of the narrow-band lambda sensor, so it will always read rich.
I'm not really sure why a narrow-band lambda sensor is even part of a Cerb's design unless the map that TVR originally sold it with was seriously hamstrung to *try* and provide a stoich value at MoT-able readings (idle and about 2500rpm). Surely they can't be aiming at stoich values for normal use?
The Emerald-equipped cars will have been mapped with a wide-band lambda sensor which allows an actual numerical reading to be given, not just a plus or minus a small percentage either side of stoich. The RR operator (Jools in the case of my car) will have mapped the car to a target AFR and then tweaked it a little to give the best power at each speed and load site
and then the the map will have been "fixed" or, in other words, set to ignore the output from the narrow-band lambda sensor from then on.
You can now buy cheap wide-band lambda sensors with in-line control boxes, allowing you to leave them permanently wired into your car's ECU, and with the latest version of the Emerald you can use that wide-band lambda sensor to self-map. You'll have to know what your target AFR should be at different speed and load sites, but the possibility exists now and it works very well.
I'm sure this feature is not unique to the Emerald but it's a cheap unit and has a lot of support from both enthusiasts and professionals like Jools.
mars said:
Don't even try to make sense of the readings a narrow-band lambda sensor gives you. The operating range of these units is only a very small percentage either side of stoich (14.7:1 AFR or lambda = 1).
For max power a Cerb probably runs around 12.5:1 which will be well outside the operating range of the narrow-band lambda sensor, so it will always read rich.
I'm not really sure why a narrow-band lambda sensor is even part of a Cerb's design unless the map that TVR originally sold it with was seriously hamstrung to *try* and provide a stoich value at MoT-able readings (idle and about 2500rpm). Surely they can't be aiming at stoich values for normal use?
The Emerald-equipped cars will have been mapped with a wide-band lambda sensor which allows an actual numerical reading to be given, not just a plus or minus a small percentage either side of stoich. The RR operator (Jools in the case of my car) will have mapped the car to a target AFR and then tweaked it a little to give the best power at each speed and load site
and then the the map will have been "fixed" or, in other words, set to ignore the output from the narrow-band lambda sensor from then on.
You can now buy cheap wide-band lambda sensors with in-line control boxes, allowing you to leave them permanently wired into your car's ECU, and with the latest version of the Emerald you can use that wide-band lambda sensor to self-map. You'll have to know what your target AFR should be at different speed and load sites, but the possibility exists now and it works very well.
I'm sure this feature is not unique to the Emerald but it's a cheap unit and has a lot of support from both enthusiasts and professionals like Jools.
For max power a Cerb probably runs around 12.5:1 which will be well outside the operating range of the narrow-band lambda sensor, so it will always read rich.
I'm not really sure why a narrow-band lambda sensor is even part of a Cerb's design unless the map that TVR originally sold it with was seriously hamstrung to *try* and provide a stoich value at MoT-able readings (idle and about 2500rpm). Surely they can't be aiming at stoich values for normal use?
The Emerald-equipped cars will have been mapped with a wide-band lambda sensor which allows an actual numerical reading to be given, not just a plus or minus a small percentage either side of stoich. The RR operator (Jools in the case of my car) will have mapped the car to a target AFR and then tweaked it a little to give the best power at each speed and load site
and then the the map will have been "fixed" or, in other words, set to ignore the output from the narrow-band lambda sensor from then on.
You can now buy cheap wide-band lambda sensors with in-line control boxes, allowing you to leave them permanently wired into your car's ECU, and with the latest version of the Emerald you can use that wide-band lambda sensor to self-map. You'll have to know what your target AFR should be at different speed and load sites, but the possibility exists now and it works very well.
I'm sure this feature is not unique to the Emerald but it's a cheap unit and has a lot of support from both enthusiasts and professionals like Jools.
I was pretty sure that when jools fits an emerald he doesn't even connect it to a lamda sensor. The thing runs open loop all the time despite the chap at emerald saying it runs with a wideband sensor.
I'd have though it likely that Jools maps an engine with a wideband, although not necessarily so, but then he leaves it "open" once the mapping is finished. I wasn't present when my car was done, as Jules owned it then, so I can't be sure.
DW used to map without a wideband until they became attractively priced over the past 5 years or so and his results were always fine. A wideband only makes the arrival at the correct map easier/quicker and confirms what the RR operator knows from the RR output.
DW used to map without a wideband until they became attractively priced over the past 5 years or so and his results were always fine. A wideband only makes the arrival at the correct map easier/quicker and confirms what the RR operator knows from the RR output.
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