Open ECU?

[Dimman]

Originally Posted by jedibow

Absolute load is the load value the ECU uses to determine the ignition timing as it has been compensated for variables that effect volumetric efficiency (barometric pressure, and temperature), this is the reason my car at 5500 feet is running more timing than a car at sea level because the absolute load traces the timing map at a load of 80, instead of the full 100, and the timing value for those cells are higher than the cells in the 100 column.

I posted the ignition map for my Evo (any Evo owners on this site do not steal my tune

to hopefully give you a better understanding. Red would represent absolute load, blue calculated load...

So the drop in Absolute load corresponds to the torque dip?

[jedibow]

Originally Posted by Dimman

So the drop in Absolute load corresponds to the torque dip?

That is one hypothysis, atleast my log shows that the VE of the engine drops in that area. So I believe that yes it is linked, now we just have to figure out why the VE drops in that area, and causes the torque dip. What is interesting is that the factory tune increases timing in that area, which in most cases increases VE, but for some reason it doesn't in this car

[Dimman]

Originally Posted by jedibow

That is one hypothysis, atleast my log shows that the VE of the engine drops in that area. So I believe that yes it is linked, now we just have to figure out why the VE drops in that area, and causes the torque dip. What is interesting is that the factory tune increases timing in that area, which in most cases increases VE, but for some reason it doesn't in this car

Is it possible for you to add MAP and what the AVCS are doing to the Engine load and Absolute load graph?

And by VE you mean volumetric efficiency?

[jedibow]

Originally Posted by Dimman

Is it possible for you to add MAP and what the AVCS are doing to the Engine load and Absolute load graph?

MAP I can do another log tomorrow as I did not log the MAP or the MAF in this run, but yes I can get MAP, and MAF values. AVCS no, not yet as this in not a standard CAN PID, and whe ECU will have to be cracked to log SSMII data, which is what AVCS is.

Originally Posted by Dimman

And by VE you mean volumetric efficiency?

Yes that is correct.

[Dimman]

Originally Posted by jedibow

MAP I can do another log tomorrow as I did not log the MAP or the MAF in this run, but yes I can get MAP, and MAF values. AVCS no, not yet as this in not a standard CAN PID, and whe ECU will have to be cracked to log SSMII data, which is what AVCS is.



Yes that is correct.

D'oh! What the cams are doing in the dip will give massive insight into what we can do with it.

[jedibow]

Originally Posted by ahausheer

Im new to this type of thing and have a question. Does the above support the idea that the drop in torque is due to intake harmonics/pressure? Also why is the ignition timing advance (bottom purple) so uneven.

This is from the air raid intake thread, but it supports your idea, if you notice most of the gains from the intake are in the torque valley, and the harmonics have definately changed due to there intake design.

The ignition timing curve is so uneven because that is the way toyota/subaru tuned it...

[jedibow]

Originally Posted by Dimman

D'oh! What the cams are doing in the dip will give massive insight into what we can do with it.

I was thinking it was fuel transition related, but you know you do bring up a good point.

[Dimman]

Originally Posted by jedibow

I was thinking it was fuel transition related, but you know you do bring up a good point.

If we're talking strictly about VE (and not combustion efficiency) we are only concerned with cylinder filling. And this is the realm of cam timing based on intake speed and acoustics (intake and exhaust).

If we are getting positive exhaust returns and negative intake returns in the dip, this could massively hurt filling (and therefor torque). But the output in the 'dip' is actually pretty good/normal for a 2.0L na motor. It could be that the engine is reducing cam overlap here to reduce a really strong torque hole from the 'bad' acoustics. Or advancing/retarding the intake cam to 'dodge' bad returns.

Too much to speculate on without really knowing what the cams are doing.

And I'm still curious about the erratic low-mid range 'noise' in the Engine load line...

Thanks again for the help.

[serialk11r]

Originally Posted by Dimman

If we are getting positive exhaust returns and negative intake returns in the dip, this could massively hurt filling (and therefor torque). But the output in the 'dip' is actually pretty good/normal for a 2.0L na motor. It could be that the engine is reducing cam overlap here to reduce a really strong torque hole from the 'bad' acoustics. Or advancing/retarding the intake cam to 'dodge' bad returns.

I think this is the strongest hypothesis, since on a cam phasing only engine, cam advancing always increases overlap. If the intake harmonics are such that there are "bad acoustics" in that range, then a large amount of overlap is not going to work because of the extra internal EGR. I think we'll see that the intake cam opening will be retarded to reduce overlap. The reduced spark timing and lower AFR are I'm guessing to counter the effects of said EGR to prevent knock.

[E92M3Guy]

Originally Posted by jedibow

Correct these are non-standard OBD II PIS's they are CAN standard to a degree, I'm having to locate the request ID's manually as they do not line with the the standard CAN PID's.

Arghx7 and I have figured out it is an issue with EvoScan not the CAN port, for some reason the html file in evoscan does not link the PID's to request ID's, that would have been nice, as it would be easy to locate what I needed to log, and have the correct scalings ready to rock.

If it will help, I've been taking complete data logs of the engine CAN bus and reverse-engineering the data locations. I suspect your tool communicates with the ECU via D-CAN (diagnostics CAN) and that's why you're sending PIDs to the ECU and getting response data. I'm looking at the raw data on the bus itself. Let me know if there's any of the raw data might be helpful.

[arghx7]

Thanks for your continued efforts. The more useful data we can get, the better we can understand the engine. I'm still waiting on the emissions and fuel economy certification filing so we can try to figure out why the automatic is rated at so much more fuel economy. That's another thing I'd like to look into.

Now I'm taking a look looking at the CSV files. I don't see fuel trims or fuel pressure, so I'm not sure what's going on with that. I moved the decimal places around for the cat temp. Assuming it's the right data, it seems to have a slower refresh rate than other parameters. The trend line kind of makes sense but I am not sure I 100% trust the cat temp estimate data.

So here are some new charts (I have trouble reading Jediblow's screenshots):



Keep in mind that Jedibow's car is at high altitude. Things I notice from this:

1. The timing "dip" corresponds to a local maximum in the absolute load/pumping efficiency.

2. The estimated cat temp, assuming we can trust the data, peaks around 900C at redline. This is roughly what I predicted the max temp to be. This cat temp occurs at peak enrichment/richest AFR.

3. Generally speaking, timing advances as pumping efficiency is decreasing and retards as pumping efficiency is increasing

4. Up to about 4000rpm, the engine is running at max WOT spark advance and a commanded AFR which should help torque output. This seems to correspond to the torque "bump" (ie, before the "dip"). I'd like to see cam phasing data to learn more, but that will probably have to wait until ECU datalogging becomes available.

Now what is absolute load as reported over the CAN bus? Absolute load is a pumping efficiency calculation.



Absolute load is not exactly the same as the grams/sec load term used in internal Subaru ECU calculations. They are directly related, yes, but they aren't the same. When absolute load goes up, grams/sec should go up.

According to the ECUtek guy's post, these are the stock basic ignition timing map and basic commanded AFR maps:





notice the load axis is in grams/sec.

Just looking at this data we have so far, the stock maps definitely seem to be tuned to maximize torque under 4000rpm.

[E92M3Guy]

Originally Posted by arghx7

Now I'm taking a look looking at the CSV files. I don't see fuel trims or fuel pressure, so I'm not sure what's going on with that. I moved the decimal places around for the cat temp. Assuming it's the right data, it seems to have a slower refresh rate than other parameters. The trend line kind of makes sense but I am not sure I 100% trust the cat temp estimate data.

There's two things I can think of that might explain this. 1) Refresh rate of D-CAN; 2) Refresh rate of the sensor itself.

1. D-CAN shares a single CAN address to receive data. If you request more than two parameters (RPM, Lambda, timing, etc.), then it most likely extends the request to a multi-frame CAN message. This means refresh gets slower when you request more parameters because all of the values must clear the CAN bus before the next request is made.
2. The sensor itself might have a slow refresh rate. In this case, the ECU is reading the sensor data at a slower rate, and that's why it only updates in your logs at such a slow rate as well. For example, RPM data on my BMW CAN bus is updated every 1ms, but temperature data is updated every 1s. D-CAN pulls the data down every 70ms (on the BMW), but you can clearly see temperature sensor refresh rate matches the engine CAN bus at 1s update intervals.

[johnbradley]

Originally Posted by jedibow

Okay so this is the last log again 3rd gear pull on the freeway from 2500 RPM to Redline. I have included Maf Flow, same log as previous with appropriate scaling, a close up of Timing and RPM, AF Map (not AFR, but what the ECU is telling the car to run), and the map tracer now works so...

Here we go

George

Your log of MAF voltage parallels the powerband perfectly. The dip in torque is related to Airflow and I would wager its AVCS dropping cylinder pressure to prevent knock at peak load.

After reading the rest of the thread and seeing the ignition screenshot from ECUtek, the timing is low there but I havent ever seen ignition timing affect airflow. It wont be helping of course but I am not sure thats the whole cause. The other thing I wonder is if its like the GTR and not a real number anyway but a calculated burn rate vs ignition timing number.

[jedibow]

Originally Posted by johnbradley

Your log of MAF voltage parallels the powerband perfectly. The dip in torque is related to Airflow and I would wager its AVCS dropping cylinder pressure to prevent knock at peak load.

Don't tell me you jumped the Evo also? John were the scalings in EvoScan made specifically for the Evo X? for some reason certain values do not log correctly for this vehicle, I.E. Maf reading 10,000 ???? throttle percentage 80, at WOT, O2 feedback 65****,

Thanks John

P.S. I don't mean to put you to work HaHA