Good Air/Fuel Targets for Safe NA Horsepower
03-25-2008, 11:36 PM
#76
I though rotary's need a richer A/F ratio for cruising since the combustion is held for so long in the engine? I'm wanting to get the Cobb Accessport but using the tuning software to make it personal for the car.
03-26-2008, 12:43 AM
#77
I shoot for 15:1 or leaner in the closed-loop areas below 4500 RPM and 14:1 above.
That way you have an economy range and a little more fuel when raging along at higher RPMs to cool the exhaust
Mazda shoots for 14:1 and 12.5:1 in the same ranges respectively, mainly to support CAT longevity.
That way you have an economy range and a little more fuel when raging along at higher RPMs to cool the exhaust
Mazda shoots for 14:1 and 12.5:1 in the same ranges respectively, mainly to support CAT longevity.
03-26-2008, 01:28 AM
#79
Of course - me.
The last three tankfulls (despite driving like the typical lead-footed moron that I am) all yielded 15% more miles.
The current tank is shaping up the same way - I still have 1/8 left and I'm well over 200 miles already (I ALWAYS get 200 per tank).
The real test will be on Monday when I drive to Vegas. It'll be my first long highway trip on the current calibration.
The last three tankfulls (despite driving like the typical lead-footed moron that I am) all yielded 15% more miles.
The current tank is shaping up the same way - I still have 1/8 left and I'm well over 200 miles already (I ALWAYS get 200 per tank).
The real test will be on Monday when I drive to Vegas. It'll be my first long highway trip on the current calibration.
03-26-2008, 05:18 AM
#80
I disagree. Your implying that Mazda targets 14.1 in closed loop, which is not what I have seen from experience. I have posted a number of times about this before, and in closed loop, the PCM does a very good job of mantaining 1.0 lambda within a very tight tolerance (about .004) from memory. (0.996 lambda is 14.64:1, if your fuel is 14.7 stoich).
C'mon guys, lets start embracing lambda a bit more.
Lambda Rocks! 
Cheers,
Hymee.
C'mon guys, lets start embracing lambda a bit more.
Lambda Rocks! Cheers,
Hymee.
03-26-2008, 07:32 AM
#81
My Absence
I’ve been asked by several people why I am not on the forum responding to a lot of the posts. That is a fair question and deserves an answer.
I started on the forum with two bad mouthing sessions. I was told in no uncertain terms that my posts should be taken off line and that those types of comments were not helpful or welcome. It was not pleasant to hear but those people were right. I apologized to the one group were my comments were not accurate and took my feelings off line on the second.
I will post when I can contribute to the better good. It is hard for me to read the types of posts that have been made and not want to “return fire” so I have chosen not to participate. I will gladly respond to positive PMs so please feel free to PM me if I can be of any assistance.
Thanks, Lola
I started on the forum with two bad mouthing sessions. I was told in no uncertain terms that my posts should be taken off line and that those types of comments were not helpful or welcome. It was not pleasant to hear but those people were right. I apologized to the one group were my comments were not accurate and took my feelings off line on the second.
I will post when I can contribute to the better good. It is hard for me to read the types of posts that have been made and not want to “return fire” so I have chosen not to participate. I will gladly respond to positive PMs so please feel free to PM me if I can be of any assistance.
Thanks, Lola
03-26-2008, 12:50 PM
#84
There are no absolute target lambdas.
The "chemically correct" lambda is 1.0.
Best economy falls in a range, best power falls in a different range and best torque falls in another range.
Mazda's target lambda in closed loop is all over the place. They don't just have a big "1.0" in the middle of the fuel mapping.
The closed-loop target is .96 to 1.01. Then, there is a modifier that "bends" the target lambda based on time in gear from 89% to 110%.
So, the net target a/f for closed loop can be anywhere from 12.8:1 to 16.33:1!
The "chemically correct" lambda is 1.0.
Best economy falls in a range, best power falls in a different range and best torque falls in another range.
Mazda's target lambda in closed loop is all over the place. They don't just have a big "1.0" in the middle of the fuel mapping.
The closed-loop target is .96 to 1.01. Then, there is a modifier that "bends" the target lambda based on time in gear from 89% to 110%.
So, the net target a/f for closed loop can be anywhere from 12.8:1 to 16.33:1!
03-26-2008, 01:12 PM
#86
No means yes
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Of course - me.
The last three tankfulls (despite driving like the typical lead-footed moron that I am) all yielded 15% more miles.
The current tank is shaping up the same way - I still have 1/8 left and I'm well over 200 miles already (I ALWAYS get 200 per tank).
The real test will be on Monday when I drive to Vegas. It'll be my first long highway trip on the current calibration.
The last three tankfulls (despite driving like the typical lead-footed moron that I am) all yielded 15% more miles.
The current tank is shaping up the same way - I still have 1/8 left and I'm well over 200 miles already (I ALWAYS get 200 per tank).
The real test will be on Monday when I drive to Vegas. It'll be my first long highway trip on the current calibration.
Please let us know how it goes 
03-26-2008, 01:27 PM
#88
No means yes
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Not quite, but almost
03-26-2008, 06:06 PM
#92
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I disagree. Your implying that Mazda targets 14.1 in closed loop, which is not what I have seen from experience. I have posted a number of times about this before, and in closed loop, the PCM does a very good job of mantaining 1.0 lambda within a very tight tolerance (about .004) from memory. (0.996 lambda is 14.64:1, if your fuel is 14.7 stoich).
C'mon guys, lets start embracing lambda a bit more. Lambda Rocks!
Cheers,
Hymee.
C'mon guys, lets start embracing lambda a bit more.
Lambda Rocks! Cheers,
Hymee.
I have logged hrs and hrs of data and in the past month and at steady closed loop it sits pretty damn stagnate at around .99 -1.0 lambda.
03-26-2008, 06:19 PM
#93
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I disagree. Your implying that Mazda targets 14.1 in closed loop, which is not what I have seen from experience. I have posted a number of times about this before, and in closed loop, the PCM does a very good job of mantaining 1.0 lambda within a very tight tolerance (about .004) from memory. (0.996 lambda is 14.64:1, if your fuel is 14.7 stoich).
C'mon guys, lets start embracing lambda a bit more. Lambda Rocks!
Cheers,
Hymee.
C'mon guys, lets start embracing lambda a bit more.
Lambda Rocks! Cheers,
Hymee.
03-26-2008, 06:30 PM
#94
You also want to check it at a range of calculated loads below the closed-loop exit points from idle to redline.
Logged data is a bit like checking to see who won the sprint by monitoring their pulse.
Don't forget - I am looking at the actual Mazda tables, not just going on my logged data, even though that too is at odds with your efforts.
03-26-2008, 10:05 PM
#96
The reason is that Lambda is invariant. AFR, when expressed as a ratio is not. What is the (ideal) stoich AFR for gasoline? 14.7:1 is the common answer. But what RON is that? Depending on the batch it might be 14.67. Another brand / RON/PON/MON might be 14.69. Alcohol is different again. Deisel is again different. What about if you have pre-mix in your fuel? What is the "stoich" value then?
The same thing applies for the AFR for "best torque" and "best power" and best BSFC. It is a number that is dependant on the exact blend of fuel.
Lambda is different, and this is why. Lambda 1.0 is stioch "ideal", meaning complete burning of oxygen, not rich, not lean. It is invariant of fuel. Petrol, Gasoline, Diesel, Methanol, Nitro-methane, C16, C25, AVGAS. If you know you need to tune for a certain lambda, then a variable is removed from the equation. And the conversion between lambda and AFR is simple, but it does involve knowing the stoich value of the fuel. So if your fuel is stoich of 14.7:1, and you have a lambda reading of 0.95, you multiply 14.7 * 0.95 and your AFR is 13.965:1. But that is only true if your fuel is 14.7. Lambda, however, doesn't change.
I hope that is helpful.
Cheers,
Hymee.
The same thing applies for the AFR for "best torque" and "best power" and best BSFC. It is a number that is dependant on the exact blend of fuel.
Lambda is different, and this is why. Lambda 1.0 is stioch "ideal", meaning complete burning of oxygen, not rich, not lean. It is invariant of fuel. Petrol, Gasoline, Diesel, Methanol, Nitro-methane, C16, C25, AVGAS. If you know you need to tune for a certain lambda, then a variable is removed from the equation. And the conversion between lambda and AFR is simple, but it does involve knowing the stoich value of the fuel. So if your fuel is stoich of 14.7:1, and you have a lambda reading of 0.95, you multiply 14.7 * 0.95 and your AFR is 13.965:1. But that is only true if your fuel is 14.7. Lambda, however, doesn't change.
I hope that is helpful.
Cheers,
Hymee.
03-26-2008, 10:29 PM
#99
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What I still can't quite wrap my head around is how what the wideband sensor sees is translated to a lambda value. The sensor is simply measuring the difference in O2 content between the exhaust and the outside air. How does that translate to a lambda value?