I've been geeking out on my FlashPro for over a year now, and have literally created and tested over 600 calibrations. However, I never could figure out the purpose for the WOT lambda adjustment tables until reading one of Hondata's posts last week. Since this table doesn't seem to be discussed at all in the FlashPro help documentation, I figured I would share what I learned about it over the weekend.

It turns out that the purpose for Fuel Low and Fuel High tables are all about mapping the air flow characteristics of the engine at various loads and RPMs. The ECU then uses the air flow mapping to determine how much fuel to provide based on the many parameters and tables that define fueling. This means that if your "breather mods" stay constant (I / H / TP / E), then your really only need to adjust the Fuel Low and Fuel High tables once, then leave them alone! Once it is properly tuned, you should do all your fuel tuning with the other tables.

Since I wasn't aware of the functionality of the WOT lambda adjustment tables, I did all my WOT fuel tuning directly in the Fuel Low and Fuel High tables. This worked okay, but every time I wanted to try a new fuel mix, I had to spend signifcant amounts of time retuning the Fuel Low and High Tables trying to smooth out the saw tooth effects that would appear in my AFR plot. I couldn't figure out why I couldn't just add 2% to the Fuel Low and High tables, and expect to see my AFR move exactly 2% with out exhagerating the saw tooth. Well, it turns out that I was just fighting against the WOT lambda adjustment table, which didn't match my tuning target at all! The default values for the table tell the ECU that the desired AFR at WOT starts out at 12.5 up to 5K RPMs, then drops to 12.1 up to 7500 RPMs, then drops to 11.8 up to redline. However, I was trying to tune for a constant / flat AFR of 12.5 across the whole RPM range.

What wasn't clear about the WOT lambda adjustment tables was that the ECU uses those targets to calculate a fuel compensation. If the target is 14.7, then the ECU would apply a compensation of 0% to the corresponding value in the Fuel Low or Fuel High table. However, if the target is 12.5, then the ECU will apply a fuel compensation of +15% to the Fuel Low or High table. So in my case, the ECU would apply +15% at WOT up to 5K RPMs, then it would interpolate between 5K to 5500 RPMs where the ECU would start applying +18% up to 7K, then +20% up to redline. Since I was trying to achieve a flat AFR, I was adjusting the Fuel Low and Fuel High tables to effectively remove 3% between 5K and 7K, then remove 5% above 7K. However, since my table indexes didn't match the WOT lambda adjustment tables, my compensations were never close enough to cancel them out, which caused my saw-tooth AFR patterns.

So this weekend, I changed my WOT lambda adjustments to match my desired AFR (12.5 across the whole RPM range), then I retuned my Fuel Low and Fuel High tables until my actual AFR is where I want it. The result is now a MUCH smoother AFR plot with very little fluctuation, and suprisingly, more power! My Fuel Low and Fuel High tables also look much "prettier", and match the injector pulse width plot better.

Now that I have my Fuel Low and Fuel High curves set "right", I believe it will be very easy for me to try out different WOT fuel targets by changing ONLY the WOT lambda adjustment tables!

I would be really interested to know how many people have FlashPro tunes with completely "stock" WOT lambda adjustment tables ...

 

Oh wow, I feel dumb now haha. This makes MUCH more sense to me now. Thanks for this good post Gernby.

 

So I guess this would mean if you set all the values in the WOT lambda adjust tables as 14.7 then it would apply 0% during WOT and would just fuel according soley to what the values are in the fuel low and high tables?

This explains why my fuel high table was forming a map that I wouldn't really expect to see whilst I was mapping for a flat 12:1 AFR at WOT as the fuel values would peak somewhere around 7-8k and then actually would flatten and then reduce slightly up towards redline in order to keep at 12:1.
I shall reduce the values in the WOT lambda adjust to 12 and remap it. hopefully this will result in a fuel map that looks something more like I was expecting.

 

I asked Jeff Evans about this - his reply.

"From my experiences doing some trial and error with the WOT adjustment tables there was no significant impact on a/f repeatability or consistency. You can dial in closed loop function to be applied to WOT for consistency, but I was getting some odd partial throttle closed loop behavior in doing so. Until I can get a clear answer from Hondata exactly how the tables work (cause/effect) I leave them alone. "

 

An update from Jeff -
They are based on uncorrected A/F, BUT they are a representation of % fuel difference between 14.7:1 and the ratio expressed in the mapping. So if the value is set at 12.5:1, its about 16-17% difference added to the main fuel mapping.

 

I agree with everything EXCEPT the first part about it being based on uncorrected AF. It isn't based on AF at all. It's just a percentage adjustment that has been represented as an AF value.

 

there is some thing wrong with this table . my WOT lambda adjustment was 12.46 , then I tuned my actual AFR to 12.5 (NGK wideband) , then I shifted my WOT lambda adjustment value to 13 BUT my actual ARR jumped to 13.5 !!!!!!! it suppose to jump to 13 . when I looked at my data log I was shocked when I saw that my AF value is ~12.9 .

I think that table use uncorrected AF to adjust AFR (I'm not sure I have to do more tests).

 

Let me get this straight ...

1) You altered your calibration so that the WOT lambda tables (high and low) had 12.46 in the appropriate columns for all RPM indexes.
2) You flashed that calibration to your ECU.
3) You datalogged your WOT AFR's with an aftermarket / external wideband O2
4) You adjusted the fuel tables in the calibration from step 1 based on the datalog from step 3.
5) You flashed that calibration to your ECU.
6) You repeated steps 3-5 until your datalogs showed a consistent, flat, smooth AFR of 12.5 across the whole RPM range at WOT.
7) You altered your calibration once more to change the WOT targets for all RPM indexes to be 13.0.
8) You flashed that calibration to the ECU
9) You datalogged your WOT AFR's, and found that the result was 13.5.

Is this correct?

If so, then I think you might have something wrong with your wideband sensor or installation. The ECU never uses any feedback from the O2 sensors at WOT, so it isn't based on AF or AF Corr at all. The values in the table are really just a strange representation of a percentage adjustment (from stoich).

 

yes , you are right I have calibrated my wideband (in fresh air) the wrong way .

I will do a final test for AFR when I finish my 2nd midterm exams . I will install a new primary O2 sensor and I will replace the wideband sensor (I have only use it for one week) for a new one .