ok, i dont think that will work, cuz its just bringing it down to lambda and then multiplying by 14.2 and loosing all its resolution..
anyother ideas?
ok, i dont think that will work, cuz its just bringing it down to lambda and then multiplying by 14.2 and loosing all its resolution..
anyother ideas?
Divisor: 0.7336
Adder: 8.804
That'll show AFR in the scanner using 14.2 as stoich.
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wrong again....
dont try to change the factory multiplier value...
the multiplier doesnt change just because the components cant do the far extremes of the scale properly...
it may only output a minimum of .3 volts and a max of 4.87 volts, but the scale is still the same and the multiplier is still the same
volts/ .7143 + 8.63 gets you 14.2 as stoich
a little spreadsheet to help out with it as well...
Last edited by S2H; 07-28-2010 at 06:34 PM.
-Scott -
You're wrong, and overly pompous, but it is clearly pointless.
To carlrx7... 0.62 lamda for 14.2 stoich is 8.804 AFR. This ends up being your adder. The divisor is just 5/(14.2*0.48). The 0.48 comes from the range of the AFX (.62-1.1).
As far as minimum and maximum analog output... That min/max voltage doesn't dictate the equation for the sensor. Just because it won't put out true 0v or true 5v doesn't mean the equation shouldn't use values at 0v and 5v. There's no "changing the factory mutiplier"... It's just rescaling the equation based on the stoich value somebody is working with.
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To resale you don't change the division.... just because your stoic value is different doesn't mean your multiplier scale changes. You simply shift over the afr added..
If you don't understand how a simple transfer function works... then you need to go back to 8th grade algebra
A little math...let's use lambda for our examples too.
Lambda 1.0 = 3.98 volts = 14.57 afr default values on afx wideband
Lambda .85 = 2.45 volts
Scale of 14.2 stoic
14.2 x 0.85 = 12.07
2.45/.7143 = 3.43 + 8.64 = 12.07
Simple math...
Last edited by S2H; 07-28-2010 at 08:05 AM.
-Scott -
Never mind. I figured it out.
Last edited by Sherman; 07-27-2010 at 10:43 PM.
Clearly you are the one that doesn't get it. A wideband puts out a LAMBDA range, not an AFR range. That range for the NGK AFX is 0.62 to 1.1 lambda.
For pure gasoline, that's 9.10 to 16.15.
For E10, that's 8.80 to 15.62.
For E85, that's 6.05 to 10.74.
For somebody spouting off about transfer functions so much, you sure are confused.
Last edited by DSteck; 01-02-2011 at 05:41 PM.
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by your fuzzy logic... every unit sold gets its own new transfer function multiplier...
so cheaper parts that dont output the extremes mean that all of the equation must be wrong in your book...
they tell you that the multiplier is 1.4 and that stoich by the device = 14.57
when you do the backwards math it lines up perfectly with a range of 5~16 AFR and roughly a lambda of 0.62~1.10(which would be nice if they would use 3 or 4 decimals for better accuracy with lambda as by nature of being a smaller value makes it less resolution and therefore less accurate.)
feel free to call NGK and tell them that their hundred thousand units sold are all wrong...
especially when they have been dubbed one of the most accurate budget widebands in the market and have one of the best upper end widebands as well.
My whole point is that you dont change the multiplier..yet you have multiple posts with different multiplier values...
the multiplier does not change... it is hard coded into the unit... the unit will always output the same voltages for stoich regardless of what fuel you are using...
when you change the divisor, you change the value that represents stoich...
Last edited by S2H; 07-28-2010 at 08:07 AM.
-Scott -
Maybe if you bothered to check the various transfer functions that I've posted, you'd see that stoich occurs at the exact same voltage for all of them. You obviously are confused. Their gauge is hard coded for that specific AFR output, I agree... But the 5v output is for a set lambda range, and if you can't fathom that, then I don't know what to tell you. The multiplier has to change when using a different stoich value. That's the hard math of the situation. 0V is ALWAYS 0.62 lambda. For 14.2 stoich, that means 0V equates to 8.804 AFR. Consequently, the multiplier has to change so that stoich shows up for the right voltage.
Last edited by DSteck; 01-02-2011 at 05:42 PM.
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LOL...you know what... I'm gonna say I was wrong.. I was thinking voltage offset...
oh well.. party foul on my behalf...
either way.. my spreadsheet is still useful.
-Scott -
Without reading through every single post in this thread, let me just make a few key points to help keep everyone on track:
1) ANY wideband really measures lambda, regardless of what the display says. Most just multiply the lambda value by a reference number that most of the performance enthusiasts are familiar seeing. (14.7 for many, 14.56 for the NGK AFX)
2) Yes, there is a difference in display resolution when looking at two digits of lambda vs AFR, but the analog (or serial) output should still have much greater resolution than you'd ever need. Stop looking at the unit's display and just make sure you're bring LAMBDA into your logger properly.
3) When setting up your logger, just input the conversion from analog input volts to lambda and forget about AFR. (I'm repeating this for a reason.)
4) The sooner you drop the security blanket of AFR and start using Lambda like the big boys, the sooner you'll be able to make it on the tuning playground of life. AFR opens the door for confusion based on fuel blends. Lambda stays consistent when taking measurements. (Just make sure you've defined the stoich point in the PCM properly!) Make your calculations and corrections in units of lambda and lambda error and it will make your life easier in the long run.
I've been using Lambda for some time now and I must say it makes life so much easier once you are used to it!
Really sucks though when I revert back to the older LT1's and I have to use the display on the NGK and a calculator to make my adjustments to the tables. I know there is a way to log voltage through the LT1 PCM's but I don't really care to go that far with hooking that up each time one comes along haha.
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ShorTuning
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FYI, when using the lambda transfer function for the NGK AFX, as long as I've got a GOOD power and ground... during warmup, when the NGK is outputting what it considers lambda 1, the scanner reads exactly 1.00. That's part of the reason I trust the lambda range they gave for the sensor.
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Áfter reading this threat i´m still confused......
I´m using NGK wideband and wante to change to Lamda to easyer adjusting in then tune when logging....
and my PCM has 14.68 stoich as a mark and using pump fuel
so what should i put in here VOLT/ ? + ? to have it right
thanks
Baezi
For lambda...
V/10.42 + 0.62
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