Discussion and questions related to the course Understand AFR

could someone please explain the have over want formula in respect to adding and subtracting fuel

i havent practiced this for over 2 year since doing the efi fundamental now i have access to a dyno 24/7 and i am practicing just need a little help thanks .it my be simple but i just need clarification

thank you

thank you

A quick point for a couple of specific application, namely reflashing Evos and Subarus, maybe the same for other OEM applictions also. The fuel tables are displayed in AFR. Most tuners ignore the actual values in the table when tuning the cars, i.e. they don't try to make the actual afr equal to the afr in the table (it never corresponds on a stock car anyway). If you are going to tune it this way the formula needs to be flipped, i.e. the correction factor needs to be want afr/have afr as larger numbers in the table equate to leaner mixtures and smaller numbers are richer mixtures.

(This is the quick way of tuning these cars. The right way is to re-scale the MAF so the AFR table matches the actual AFR and then you can just punch in the AFR values you want into the table. When rescaling the MAF, the formula would be have/want, i.e. smaller numbers = leaner, larger = richer).