MAF Scaling for Idle - Is there really a need?

If you look at the Total Correction vs MAFv graphs, you would notice that at low MAFv, my scaling is really way off. So I thought, let's give MAF scaling at idle a shot. Here's what I did:

1. Use the log data for my current MAF scale (using mickeyd2005 columns), filter out all data with throttle angle > 0 (I only want idle)
2. Filter out all data Open Loop data.
3. Keep only AFR Correction (STFT), AFR Learning (LTFT), MAFv.
4. Sum up STFT + LTFT into a new column Total Correction.
5. Sort data via MAFv
6. Interpolate the data (using williaty's method) and take the mode of values for each MAFv <= 1.37 The first time I did this, I used data logged previously for my current ROM. Once that flash has been done, I did another set of logs: 1. I startup the car, wait till it is fully warmed up. 2. Drive around bit and let it idle. 3. Take logs for about 1-3 mins. 4. Drive around abit (to eliminate heat soak) 5. Take logs for about 1-3 mins. I filtered out the data using the steps mentioned at the top. Re-flash the car. I did this a total of 3 rounds. NOTE: I only changed MAFv 0.98 ~ 1.37 (as I noticed that idling normal takes place within this range only). The changes are shown in the screenshot below. (Idle1/Idle2/Idle3 Values are the final changes that I applied to the ROM)


The idling of the car seems fine. Next I did another round of logging and use mickeyd2005's spreadsheet to analyse my MAF scaling. Here's the result:

Total Correction vs MAFv:


As you can see my low end MAFv (<1.3)

MAF Check3 (Scatter plot of Total Correction vs MAFv):


Overall, you can see that the graph above looks quite good (correction centered around 0%).

My injector scaling:



My findings:
1. Either my method is not correct or my MAFv is screwed up at low idle (hey, it could be due to my APS CAI).
2. While driving the car after the changes to my MAF table for idle, I noticed that idling corrections vary significantly after driving the car hard or at high speeds. Meaning after driving the car at 130km/h for about 10-15 mins. When I bring the car to a stop and idle, it will compensate a lot (up to 10-15%).
3. The funny thing is, before driving hard, the idling had only about 0.78% correction! Strange, isn't it?

To top it all off, my AFR Learning A has worsened from -4 to +9 (see screenshot below). My AFR Learning D also suffered abit this time around from 0 to -0.49 (I'm surprised about this - might need some monitoring).


Well, I'm not sure why it behaves this way but I have decided to revert back to my original MAF table BEFORE the changes for Idle (I considered it a failure). But I did make one more change though, to my MAFv 1.29 and 1.33 as in my logs for Idle changes, it shows the 0% correction in this range (but not for MAFv less than 1.29)

The top MAF table are the changes (changes in grey) and the bottom MAF table are values BEFORE the idle MAF changes.



I'm going to go through another round of logging to see if my MAF table has improved at MAFv 1.3 range. One thing's I've learned this weekend, MAF scaling for idling is not easier that CL Scaling as well. But given that it only affects idle, if a car is already idling fine - is there REALLY a need? Hmmmm...

Will keep you guys posted. :-)