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AFR Table - Filling in the Gaps

Understanding AFR

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Discussion and questions related to the course Understanding AFR

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After watching the Understanding AFR course I had a look at my Lambda Target Table and other fuel tables and it seems the operating philosophy is to run lambda 1 unless there is an extended period of WOT (>30s) or unless component protection is activated. I decided to modify the stock lambda target table to the recommended starting values in the course and I was then planning to evaluate the AFR changes. The before and after tables are attached.

I then used the 4 way interpolation function to smooth out the table which seems to do a good job of smoothing the table but I think the values are now too far away from my targets.

Attached Files

I would not worry about "smoothing" the table, the values will be interpolated (like your graphic shows), and will provide intermediate targets to change the fueling just fine.

I'm not sure those are the right targets, but that's why you test and tune.

Good Luck!

Hi David,

Thank you for the response.

So leave the targets as per the Lambda Target Bank 1 (After) JPG and the ECU will interpolate between the cells?

What jumps out at you as being incorrect?

The .95 Lambda at 0-40 kPa above 5k RPM. Not sure what you're trying to do here. You are not making power, and the extra fuel won't help cool the combustion, might be it won't matter if you have decel fuel cutoff (sometimes referred to as DCFO) active, which makes no combustion happen.

And why go back to Lambda 1.0 after reducing the lamba high-load, low RPM? To me, as the load goes up, the lambda always stays the same or goes down (richer), I would never see a reason to have it go leaner as the load increases. Idle conditions are the exception to this rule, often you want to run a slightly richer mixture at idle to help stability, eliminate popping, etc.

These values have been taken directly from the course content (see below) and were to be used a starting point for the AFR table.