Just a few WBO2 sensor questions

[91dime]

Forgive me as im fairly new to this. When you say log the wideband, will that be with the logging software the WB came with or the numbers in TP since I have the WB connected to the PCM.
In my Open Loop AFR vs. Temperature vs. Vacuum table, above 44 Celsius I filled the table with 14.0:1. Side note, in the table since it says vacuum, does that also mean KPA? I see vacuum, kpa and map and it all confuses me a bit on if its all the same or not.

For the formula wideband_afr/X=multiplier. I assume the WB part is what the WB shows on the dash/log, and X=multiplier is the data from the table?
so if I i was running at 16:1 at a particular spot above 44C, the formula would be 16/14 to equal 1.143, if this is correct would I add that to the VE table in that block?

Forgive me if im all wrong, the last time I did the stuff by had was with my 7747 and winaldl to log. After the 7427 upgrade iv been using blm tables in TP and spreadsheets to calculate before my exhaust leak. I have redone my fuel system to output 20 psi which is why I need to redo my fueling then timing sounds like it will be a blast to do.

[steveo]

you'll need a log with rpm, map, and wideband all together.

I see vacuum, kpa and map and it all confuses me a bit on if its all the same or not.

kpa is pressure, atmospheric pressure is around 100kpa, vacuum is the lack of pressure, more vacuum is less pressure. an engine produces more intake manifold vacuum at lower loads.

you might want to google it, as these are not just tuning concepts but also basic engine concepts, so you should read up on how pressure/vacuum works as it relates to engines, as you are tuning a gigantic piston driven air pump, you are doomed without it.

so if I i was running at 16:1 at a particular spot above 44C, the formula would be 16/14 to equal 1.143

pretty much, but you will need to do some averaging or whatever at that 'particular spot' because your wideband likely will fluctuate in many ranges due to the fact that exhaust gasses and combustion aren't really a linear thing. tuning with single data points will give you a ve table that looks like bart simpson's head. that's why tunerpro has history tables (histograms). if you have a dozen data points in a particular region and you take their average, the data will become fairly reliable, but with one or two points, who knows.

if this is correct would I add that to the VE table in that block?

no, you'd multiply it.

[91dime]

Awesome, thank you,now to start seeing how it goes.

you say multiply it, what if it were at 13:1 when its supposed to be 14:1 does it still go 13/14=.929 then multiply that cell? or is this where you do a best estimate and start averaging out and smoothing the table?

And last question for now, does the stoich AFR parameter effect open loop at all or only closed loop? I cant seems to find much info on this.

[lionelhutz]

Be careful when playing with AFR numbers. Remember, the sensor is really measuring lambda or the ratio as a percentage and not AFR as a ratio. The sensor will read a lambda of 1 for pure fuel, E10 or even E85. You are applying a multiplier/math of some value to create an analog output from the sensor and then more math to display the AFR on both the gauge and in Tunerpro. So, anything displaying a ratio can be misleading due to the math conversions from lambda to an arbitrary AFR.

A narrowband O2 sensor works the same way. It doesn't switch at an AFR of 14.7:1 but rather at a lambda of 1.

Right or wrong, I would test the wideband by running the engine closed loop at a little higher rpm than idle (maybe double idle or so) and watch if it displays a lambda of 1. If it's setup to display as AFR then it should display the "ideal" AFR that it was programmed to display.

Say you set it to display 14.7:1 as the ideal ratio. Then, at 13.2:1 you are running at a lambda of 0.9 or 10% rich. Doing the math to get lambda means it doesn't matter if you're running E10 and the ideal AFR is really 14.2:1 or even E85 and it's the 8:1 or whatever that fuel is. The meter when programmed to the ideal ratio of 14.1:1 and displaying 13.2:1 means you're at a lambda of 0.9 which just happens to be a decent starting point for the PE mode.

The other part with the test I do is that if it's AFR is out just a little then I can call the value it does display the lambda = 1 value, assuming I'm confident the sensor and controls are working and the math is programmed/matching in the sensor and gauge. If I see a reading out say 0.2:1 on the high side then I'd likely call the lambda = 1 value 14.9 and use that in the math even though in theory the gauge should be displaying 14.7:1.

[91dime]

With all these numbers I think Im going to set my gauge to use lambda instead to make it simpler, well hopefully.

Side thought, if i log the lambda and its off 10% from what i want, would I increase that cell by 10%? or is it not that simple?