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ECUs that have no built in AFR target map

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How can we modify the AFR on ECUs that have no built in AFR target map?

On the video we see that it's useful to draw up a target table manually on a piece of paper or an excel spread sheet to have a reference. but then how do we apply them?

Assuming the ECU isn't running closed loop with some internal target that you can't change. Determine the Current AFR, modify the fuel table using the Have/ Want equation - say you WANT 12.5 AFR, but you HAVE measured 14.0 (at a particular operating point); multiply the value at that condtion in the fuel table by 14 / 12.5 = 1.12 to provide the correct fuel.

This is the simplified version -- Could you supply more details about your Engine/ECU so we can make sure this applies to your case (ie, does you engine use a MAF sensor, so you are doing MAF scaling not fuel map scaling, etc)

As David mentioned, if there is no internal AFR target table then all of your adjustments to target AFR you are aiming for are done in your main fuel map.

Using the equation David has written above, it should be easy for you to make adjustments to your map to alter AFR target.