Pcv autotune and afr numbers.

[tratch2]

Hello, currently tuning with a pcv and autotune. My question is how much of a change is -10 on the pcv? If i have a afr set up on the autotune and i need to nake a change to richer or leaner should i make a change in the afr 13.5 or is that not enough? Or should i make smaller decimal point changes like 13.8 and so on? Hope this makes sence!

 

[DynojetResearch]

A -10 change in the PCV is a subtraction of 10% of the ECU's requested fuel. So if your machine is providing a 10% Duty Cycle, a -10% would reduce fuel by 1%.... Or If the ECU requested a 60% DC and subtracted 10% from that, the PCV would reduce the fuel by 6 points to 54%.

This percentage basis even carries over as a baseline for tuning when adjusting from one AFR to another. If you wish to lean out your machine from 13.5 to 13.8 as you've indicated, the percentage difference between those two AFR values is an approximation of the fuel you would subtract..... 13.8/13.5 = 1.02222 and thus would require a -2.2% adjustment in your fuel table.
Another common tuning theory for coarse adjustment to get you close is that a whole point (14.0 to 13.0) requires around a 10% change.

Hopefully this helps get you started!

~T.J.






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