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Why should an AFR deviation of a few percent be corrected in the AFR target value table instead of the MAF scaling?

Practical Reflash Tuning

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Hi

My question refers to the course "Practical Reflash Tuning" to the module "The 6 Step Process" to the video "Step 5: Optimising The Tune". In the video the following statement is made (from 2:24):

If we're still seeing a discrepancy of a few percent, rather than adjusting the MAF scaling further it's acceptable to make these corrections in the AFR target table instead.

Why should adjustments be made in AFR instead of MAF scaling at full throttle and with deviations below 5 percent? Surely it is more logical to make the changes to the cause and not the symptoms?

Greetings

This is one of those situations where theory and practical application, particularly in a commercial sense sometimes deviate. What I mean by this is that while yes, the error is a result of misreported airflow, the system can be imperfect. what I mean by this is that optimisng the same MAF frequencies under WOT ramp run conditions can often show small discrepancies when these sites are revisited under steady state conditions. While I strive for perfection, you're simply not going to get an error of 'zero' under every possible operating condition. Sometimes the quickest and easiest workaround is to manipulate the AFR target table instead. There are tuners out there who will fix all the AFR errors in this way, or at least manipulate the AFR target table until they get the desiered measured AFR and that's certainly not what I'm suggesting, however sometimes rather than chase your tale with the MAF scaling, smaller errors can be quickly sorted out in this way. Personal preference of course and if you don't need to then that's even better.

Hi Andre

Thanks for taking the time to answer my question in such detail. I have no practical experience with "Reflash Tuning".

The key to understanding your advice was in the statement "the same MAF frequencies under WOT ramp run conditions can often show small discrepancies when these sites are revisited under steady state conditions".

Thanks for your patience!

We usually reply within 12hrs (often sooner)

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