RomRaider

Yeah, the timing seems to be decreasing very slowly. Almost like it's not really following the SNT Ign Retard table and just going off the main map plus a small retard value. But it's interesting that it is applying some ignition retard just not the amount we expected it to.

What does your Ign. Retard - Negative Throttle table look like?
Also, your Change Limitation tables.

It should still extrapolate between the 60 and 80C or whatever cells, i have 3700 in last cell and it ends up being around 3500...

It is the factory ms41.1 id 90 table

So that datalog is extremely valuable!


In the datalog you can see at the 7 second mark that RPM is above the value in the Fuel Restore table so when you close throttle quickly, timing immediately goes to 0 degrees and the injectors shut off as evidenced by shutting off of the Lambda adjustments. This could be FNT logic at work. Immediate fuel cut and immediate timing retard.

It could ALSO be that damn 36 value in the Change Limitation B table because you can see busterhax lifts off at 4000 RPM at 461 Load which would primarily use that cell of the map to decide how quickly to retard timing. So it goes to 0 almost right away.
The stock MS41.1 Change Limitation B table has a ridiculously high value of 36 at the bottom right corner. This is really weird to me and not sure why they did that. It's like they are forcing a fast ramp down in timing above that RPM and Load.


Then as RPM drops below the Fuel Restore table,fuel injectors turn on again which is expected. But then the timing also goes up. This is the undesirable part for us. Fuel is restarted and the logic seems to ramp up timing quickly, about 4 degrees every ~1/4 second. This could be due to an entirely separate 'fuel cut to fuel restart' logic that I can't quite explain yet.

Then Timing starts to decay again as if sort of following the SNT Ign Retard table. But the timing ramps down really really slowly. Check out the following excerpts from the datalog.



You can see the difference in Base Timing and Actual Timing is getting larger. So I believe the Change Limitation values in those RPM ranges are too low and timing isn't being allowed to come down fast enough.

Check out this screenshot posted by Enabled on an earlier page of the MS41.1 Change Limitation tables. Try increasing those so timing ramps down faster. Hell, try that value of 36 across the whole map so there is effectively no limit to how quickly timing is allowed to retard. Or maybe something more sensible like 2 or 3.

Ok, so I finally got around to changing my sway bar bushings and valve cover gasket; so my car is completely solid and roadworthy now. It's not my daily, so it hasn't been driven in a while.

What map settings should I test, now that I had the baseline video posted earlier?


Also, I should note, that on cold engine (I suppose under 80 deg C) it is very crackly when letting off, for up to 5 seconds on deceleration in gear. I suppose we should follow what happens on the maps at those temperatures to replicate on the hot side too? Or is this just due to engine being cold/not yet reaching closed loop?

So it looks like both you and busterhax are testing the same thing. He copied over all the MS41.2 'Deceleration' tables to MS41.1 and is going to use that as a base to test.
I suggested the following values for him to test.

Do you want to try the same approach? This way we can just standardize exhaust crackle tuning for all platforms.

If so, copy all tables in the 'Deceleration' group from a stock MS41.2 file to your MS41.1 file and then edit the following maps to these values.

I also copied the decel detection values.

Ok, I'll take some time, changing the axes as well to MS41.2 when testing.

Shouldn't take more than 5 minutes with RR. I've noticed I get a nice pop/crackle when the engine first goes into decel and I log about -3* for a second, but then it bumps up to ~20* for the rest of the decel. I still need to test what mrf suggested. My car hasn't moved in a week due to crappy weather and salty roads.

Ok, I'll copy the MS41.2 deceleration maps with axes, including decel detection values, and make the suggested edits for testing. I don't have the RR Logger set up yet.. I take it logs would be helpful to test the changes?



Now if I start changing the axes from MS41.2, I'm not sure if any axes will change for Acceleration, and acceleration detection, causing the maps and behavior to be quite different?

I refrain from changing too many things/testing on the M Coupe because parts are significantly more expensive, harder to get for it, ex. Catalytic Converters if I happen to damage something.

Not necessarily. They will definitely be helpful if you don't hear any differences. But overall they will be needed to fine tune the crackle if we get it working.

I copied everything except the accel fueling.

I'm really not sure why you guys are so reluctant to use the fantastic data logger that Dale has put together. It's dead simple to use too. Just unzip the file and click on run.bat.
viewtopic.php?t=11086&start=0

Having datalogs helps figure out which maps and what part of those maps are affecting behavior.

Remember, we are in an era of scientific MS41 engine tuning. Not like the past where people would alter some bytes in some maps they 'found' and hope for the best. Now every change can be objectively verified by datalogged values.

Then I'll absolutely do datalogs at the same time.

Splendid!

Well, I used RR Logger to get the following log in neutral. No modifications to the main timing map

You can see that timing starts at 38 degrees and within a second of lifting throttle, it is in the negatives and making popping noises in the exhaust. Though, it doesn't last very long since RPM comes down so quickly while free revving. I'd love to try this in gear at speed.

Also, the stock cats and mufflers REALLY silence the noise.