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AFR Table Set Up

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If we are tuning a vehicle that we are not familiar with for the 1st time or an engine that we know but it has been more modified from other similar engines that we might have tuned , should we set up the afr table to a point that we feel safe set the map , and then proceed with small adjustment to the main table and see how the car responds ? After that should we change the values to the afr table or do we change the values to the afr table , then the main fuel table and see how the car responds ?

Also if my main fuel is in MGP should my afr table axis be with MGP or if it is from default MAP leave it as is ?

It's always safest to start with a richer AFR and then tune leaner on the dyno to see how the engine responds rather than going the other way. The starting AFR numbers I suggest in the Understanding AFR course are a good place to start.

If you're using a VE based fuel model then you need to tune the VE table until you've achieved your AFR targets and from there you can alter the AFR the engine runs in the AFR target table. In a injection time based fuel model you typically need to change the AFR by altering the numbers in the main fuel table.

The difference in MAP and MGP will depend on your current barometric air pressure and unless you're seeing dramatic variations in altitude, the two shouldn't fluctuate greatly. I tend to prefer basing my AFR targets on MAP though as it's the pressure in the manifold that is an input to the ideal gas law that defines air mass in the cylinder and this is what we're considering when we decide on AFR. To reiterate though, this is more critical on cars that are likely to experience a wide range of baro readings.

Thank you for the input . So if I set up my afr table and adjust my main fuel table but then want to see if how the car will react to a richer or leaner ratio should I first change it in the afr table and then on my main fuel table or first see if it is a positive change on my main fuel and then change it on my afr table ?

It really depends on the fuel model. With a VE fuel model, once the VE table is accurately tuned, you don't need to alter it again and any changes in AFR are made in the target AFR table so this is where you would make your changes. In an injection time based fuel model you need to change the main fuel table to affect a change in AFR.

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