AFR Error MATH on non-pro interface

[itsdaveonline]

Hello,

I am not sure why this is working. This is largely why I loathe using the newer scanner versus the older version. I am on VCM scanner 3.4.38.

Basically I have the wideband 5v hooked into the A/C pressure sensor as I don't have a pro interface. This custom MATH gives me the correct AFR from the wideband:
wideband_math.png

Now the problem arises when i do math nested inside more math. My AFR error does not calculate or work at all. It shows red. How can i resolve this?
AFR_ERROR MATH.png

Adding that this same math / custom PID concept works using the older VCM scanner. Perhaps user error?

[mowton]

You cannot copy a Math parameter into another Math function. You have to type it in long hand.

Ed M

[itsdaveonline]

You cannot copy a Math parameter into another Math function. You have to type it in long hand.

Ed M

Hey Ed,

Thanks for elaborating on the limitation. I'm not grasping how you would do this by punching in the syntax manually. Is there is special bracket, callout, or something for using user math parameter inside a math function? Didn't see anything in the help page:

https://www.hptuners.com/help/VCM-Sc...arameters.html

Thnx
Dave

[mowton]

100*((([7101.10]/1.4)+9.00)-[6001])/[6001]

s/b the same as what you have.....

What WB are you interfacing to?

Ed M

[itsdaveonline]

Hey Ed,

Thanks a bunch. I'm starting to see how this works now, basically combining both math functions into a single math function. Now the expected ERROR % isnt returning the correct data now. Still a step in the right direction and im learning..

I'm using the Ballanger AFR 500. To my knowledge it stated this in the guide: Gasoline AFR = 9.00 + Vout x 1.400. So i believe that's plugged into the math correctly?

[mowton]

Yes, they do it a bit different but should get the same answer.

What are you getting for an answer. I may not have the brackets right...

Ed M

[itsdaveonline]

Here's what im seeing, i should be close to zero % off here:

diff.png

another example where desired vs actual AFR is close @ idle:

diff2.png

Really appreciate you helping here, my head is spinning a bit from the math.

[mowton]

100*(9+([7101.10]*1.4)-14.68)/14.68

The Ballinger way is to multiply the AC sesnor volts by 1.4, then add 9, then subtract that answer from commanded AFR (14.69) then divide that by Commanded AFR and then multiply by 100 to get to percent.

The normal error math is 100*(WB-CmdAFR)/Cmd AFR

sorry.....

Ed M

[itsdaveonline]

hmm so i did that and it still was off. I did the "normal" way of doing it like this and the data now appears correct!?! No complaints here haha

100*(9+([7101.10]*1.4)-[6001])/[6001]