MAF Frq vs. G/sec at WOT

[PRAY]

I put the screen in, re did the 90* boot, and rolled my injector timing forward. The MAF is now pretty darn steady and I went from an average of 13 mpg to around 18 mpg so far. I am getting right around 23 mpg on the highway from 19 and the fuel smell has greatly diminished. It also starts and idles much better. I have much less bucking and what I do have is not from the MAF any more. I believe I may have hurt the motor. I am going to do a compression and leak down test tomorrow to see what I get. More on that when I have results. I thought about what Simon said about the throttle blade trimming so I returned all the throttle tables back to stock. I still have my PI tables zeroed up +/- 96rpm. I am going to mess with that next. It is nice having DFCO/CFCO again. That cured a bunch of the on/off throttle bucking. I still need to work on my Dynamics but don't know which direction to start. Simon, are you out there. Thanks for all the help so far. I will keep you all updated.

[swingtan]

Dynamics..... there's an interesting topic to get into.

The stock tables seem OK in some tunes but off in others. So I think there's a bit of hit and miss depending on particular engines and modifications. So here's what I think ATM. Working down the E38 tables....

1. B2021: Wall Wetting Delay - I reduce this to try and speed up the ECM's calculations. Currently I have it set on 30 while I'm playing around.
2. B2003: Stomp delta min - I have this on 3mg
3. B2002: Stomp delta min add - I have this on 0.5 to allow for a ramp out of the additional fuel instead of my stock settings that just stopped.
4. B2004: Stomp mass decay - lower in the warmer regions to slow down the fueling transients.
5. B2005: Stomp compensation - Higher in the warmer regions to add more fuel.
6. B2012: Impact Factor - Set lower at low MAP (hot and cold) and higher at high MAP when hot.
7. B2014: Evaporation factor - this will probably make the most change. I have it significantly higher at low MAP when hot, and lower at high MAP when hot.
8. B2015: Evaporation factor RPM - along with the previous, it has a big impact. I have if lower at low RPM and high at high RPM.
9. B2011: Wall Wetting Asymmetry - High at low temps and low at high temps

Tuning the dynamics is a bit of an art. I probably should write up something on that....

[PRAY]

Yes Sir, I think you should do a write up on it. Thanks for the breakdown. The EFI Live explanation's of the tables didn't give me a warm and fuzzy on what was going on and why. I will assume that I will have to bounce all of this off of my WB and the goal is to achieve steady consistent WB data at all transients and throttle positions in correlation to the commanded AFR? I do this after my WB data matches the above statement but with just the VVE table (since Dynamics are disabled when the MAF is disabled). Then enable the MAF and get it as close as possible then go after dynamics vs. the WB for the areas and transitions the MAF can't handle due to speed or it's one dimensional nature. I will also assume that my PE tables come into this and need to stay as one dimensional or consistent as possible. I.E. only commanding 12.8 afr at WOT and ramp in and out at .1. Am I tracking?

[swingtan]

The dynamics shouldn't be disabled in SD mode, they just need a lot more work....

In the E38 (and probably most other controllers), air flow is used heavily for dynamics calculations. With the MAF in place, you get an airflow spike when snapping open the throttle, as the plenum fills with air. The MAF reads this air flow and you can see it in the logged data, but you don;t see the same spike in SD mode. So you need to redo all the dynamic airflow tables to take into account there is no spike. See this example showing MAF airflow vs AIRpersec (axis shifted to allow the two traces to be seen).