Adjusting MAF with Open Loop Fuelling

[Tor]

After countless flashes, I have arrived at this and can say that I am close to being happy.



The changes made are load scaling (with the kind help of @Kodename47 ), OL/CL timers, OL fuel, and last but not least I changed the AVCS to start retarding the exhaust already from 3200 rpm. I also removed the OFH AVCS dip in the intake advance.

The AVCS changes have helped a lot on the AFR dip which used to be at it's worst at 3900 rpm (the yellow marker). It moved slightly lower in the RPM but is now nowhere near as bad.

The load scale change has removed any hesitation or choking up at low rpm. Note that the log is flooring it at 1500 rpm. Also, it was finally at reasonable IAT (starting at 23 deg C and ending at 18 during the pull). I still run the same timing and there is no knock correction worth mentioning. I suppose this should be relatively track-ready.

The AVCS changes have been made over 4 flashes where I gradually moved it lower in the rpm and compared with Virtual dyno to check for any ill effects. Besides from the car pulling cleaner in extremely low rpm I can't say there is much difference in the perceived power. Load, as an indication of torque, does seem to come on more linear and earlier (from 3500 rpm) up till the next dip at 4500 rpm.

If I wanted to go nuts, I could probably try to fine tune intake AVCS and see how that would affect AFR. But I think I am well past diminishing returns already. If anything I would probably be better off spending time rescaling MAF and rechecking the load limits. As long as my LTFT don't do any crazy things I won't be doing any more for now though.

Thank everyone for all your help and any further inputs are appreciated.

[Tor]

Coming back to this thread for some more advice.

As posted above, I ended up with a pretty linear MAF curve.

As I did a new MAF scaling I was seeking information about "Engine Load Compensation (MP)" and couldn't really find any here on the forum. Looked at RomRaider too and didn't really find the information I was seeking.

Then I stumbeld upon this video.

What the guy explains is that the ECU adds x% fuel according to rpm/manifold pressure according to that table.

If correct, as can be seen our cars add 3.12 (%?) fuel at 3600 and 1 bar. Could this be the cause of the rich dip? Does anyone have experience changing these tables?

[ame="https://www.youtube.com/watch?v=4qsVA8gCBJ4"]2008+ Subaru STI Load Compensation - YouTube[/ame]

[Kodename47]

It's only active in closed loop I believe.

[Tor]

Originally Posted by Kodename47

It's only active in closed loop I believe.

Hmm, that didn't even cross my mind. If it's only active in CL why have the compensations in the first place when fueling is controlled with the STFT?

Also, when changing a header and AVCS, could the values in this table be entirely wrong? Hence, if not making a new table, would it be better to zero it out entirely, rather than keep stock?

[freerunner]

I don't believe the map compensation tables do much in a NA application.
Last time I looked at MAP in a log there was nothing dramatic, even on sudden throttle changes.

[Kodename47]

Originally Posted by Tor

Hmm, that didn't even cross my mind. If it's only active in CL why have the compensations in the first place when fueling is controlled with the STFT?

Why do you bother to scale your MAF then?

[Tor]

Originally Posted by Kodename47

Why do you bother to scale your MAF then?

I see what you mean. Here we have a compensation to avoid another less desireable compensation.

But why wouldn't the load compensations be required when running OL as well?

[Kodename47]

Originally Posted by Tor

But why wouldn't the load compensations be required when running OL as well?

Good question. Possibly the MAF should be more accurate during WOT as there is less obstruction in airflow. At WOT the manifold should be at atmospheric pressure anyway, or above if boosted.