Is my expression wrong?

[67SS509]

I have a FJO wideband. The output voltage is 0.5-4.5 volts representing 10-20 AFR. My expression is "{EXT.AD1}*2+8.75". When I log intergrated with EFIlive it reads a whole number too low. Example: when the AFR is actually 14.6, it shows 13.6. Or is there something else I'm overlooking causing this?

[joecar]

I get: V * 2.5 + 8.75

I did:

AFR
= (V - 0.5) * (20 - 10)/(4.5 - 0.5) + 10
= (V - 0.5) * 10/4 + 10
= (V - 0.5) * 2.5 + 10
= V * 2.5 - 1.25 + 10
= V * 2.5 + 8.75

Sanity check:
plug 0.5 and 4.5 back in for V, should get AFR 10 and 20 respectively.

[67SS509]

Thanks...I'll try it tomorrow and see if it works.

[67SS509]

Made the change this morning and it works great now.

[joecar]