Data Logs! Post them here.

[Kodename47]

Originally Posted by Wayno

His AFR's were fine before he started turning the table into an incomprehensible nightmare. The simplest solution is always the best.

I agree that the load limits should be kept simple. The only reason to change them is odd rich spikes (load limit too high) or lean spikes caused by low limits. If it's anything other than those, just change the fuel table. It won't impact fuel trims as it's open loop.

The maths is just the same, if you're going 10% lean just bump the fuel table 10% richer.

[solidONE]

Originally Posted by steve99

My car is manual though and some maf sensors seem to give more problems than others , maybe their was a revision/change in sensors at some point

My car is a MY13 Manual as well. 1/13 build date with a A01C rom

edit: I totally forgot that my secondary "post cat" O2 is not stock, but an NTK brand O2 made by NGK. (don't ask...)

Originally Posted by Kodename47

Why is it a hack? The open loop fueling table isn't actually for target AFR values, it's essentially a fuel enrichment table converted to AFR values to make it easier to read/use. At the end of the day, so long as the AFRs are ideal then it doesn't matter what's in the OL Fuel table. I'd rather have the fueling right with as close to OEM MAF scale as possible, obviously with minimal LTFT, what's in the actual OL fuel table makes no difference to me.

Here's something for those playing with load limits:
Load Limit Calculator

If your load limits are causing a rich area, it should calculate the correct load and if you're lean from the limit being too low then it will also sort that out. You can change the RPM and it will adjust it as necessary and you have plots of load and AFRs vs RPM. It also proves where a lean spot is caused by something else.

@solidONE I used your data to make that, all the lean areas occur when the load also spikes (you can see it in the graphs) which is likely due to increased VE and therefore a genuine lean situation. Adding fuel is the only way to get around this, how you do it is up to you (MAF vs OL Fueling).

The only reason why it feels like a "hack" to me is simply because I'd expect the computer to be able to hit close to the requested afr and not 2.0 off from target. I'd think that something else is probably off by a good amount to require targeting a much richer afr to hit the desired afr, but that's just my thinking. Then again, my setup is quite a bit "off" from what the intended use with emissions and other hardware still intact.

If I adjusted the maf to work in OL with my setup it's going to have a huge lump at 2.8~3.0v and the fuel trims under CL operation will be just as huge. So OL Fueling adjustments it is.

Originally Posted by Wayno

His AFR's were fine before he started turning the table into an incomprehensible nightmare. The simplest solution is always the best.

This is what it looked like with the EL load limits you posted (note that the pull/WOT does not begin until 2500rpm):
http://datazap.me/u/solidone/plm85-p...zoom=1416-1630

This is with a stock unmodified load limits (also starts at 2500rpm):
http://datazap.me/u/solidone/plm3-fp...zoom=2257-2439

This is one of the earlier load limit revisions I did going WOT from 2500:
http://datazap.me/u/solidone/plm85g-...3&zoom=636-756

As you can see, it doesn't look half bad when I go WOT after 2000rpms, but If I start at 1500rpm it looks all kinds of funky.

Same log and same load limit table as the above pull:
http://datazap.me/u/solidone/plm85g-...zoom=2071-2228

I will go back to one of my previous (simpler) load limit revisions and adjust from the OL fuel table.

[Kodename47]

Originally Posted by solidONE

The only reason why it feels like a "hack" to me is simply because I'd expect the computer to be able to hit close to the requested afr and not 2.0 off from target. I'd think that something else is probably off by a good amount to require targeting a much richer afr to hit the desired afr, but that's just my thinking. Then again, my setup is quite a bit "off" from what the intended use with emissions and other hardware still intact.

I used to think similar, however just a different view is required. If you see how other ECUs (MOTEC/Link) are fuel map tuned, the cells are purely an enrichment value. You hold the engine in the cells and increase/decrease the values until you get the desired AFR. They don't use AFR values in the tables.

Now if you were to look at the open loop fuel table on the stock ECU and take 14.7 as 0% enrichment, or a base fueling value. A value of 13.2 is an enrichment factor of ~+10% etc. If that cell is still rich/lean then change the enrichment factor. If you look into the definition there's quite A bit of math gone to convert these to AFR values. If you remember that load is just g/rev then you're basically saying that at a certain RPM and g/rev then the fueling factor is x. That way you're using the fuel map to do what you want, which is the point of it, rather than not changing it as "commanded" doesn't match up with output AFR values.

It could be quite easy to change the definition to something more like that, but less people would understand it.

[Kodename47]

@solidONE, here is the fuel map with only minor alterations to the definition. Top is "standard". The middle has the 14.7 multiplier removed, looks a bit like a fuel multiplier. The bottom one is the equation in it's simplest form, which is just the middle one minus 1.



However it would then seem that the bottom one is actually a fueling enrichment percentage as such:



Leaving the formula as such:

expression="x*.78125" to_byte="x/.78125"

[solidONE]

Originally Posted by Kodename47

I used to think similar, however just a different view is required. If you see how other ECUs (MOTEC/Link) are fuel map tuned, the cells are purely an enrichment value. You hold the engine in the cells and increase/decrease the values until you get the desired AFR. They don't use AFR values in the tables.

Now if you were to look at the open loop fuel table on the stock ECU and take 14.7 as 0% enrichment, or a base fueling value. A value of 13.2 is an enrichment factor of ~+10% etc. If that cell is still rich/lean then change the enrichment factor. If you look into the definition there's quite A bit of math gone to convert these to AFR values. If you remember that load is just g/rev then you're basically saying that at a certain RPM and g/rev then the fueling factor is x. That way you're using the fuel map to do what you want, which is the point of it, rather than not changing it as "commanded" doesn't match up with output AFR values.

It could be quite easy to change the definition to something more like that, but less people would understand it.

Alright, that makes a lot of sense. Thanks for the visuals! Makes it much easier for this lowly grease monkey *points to self* to understand (save for the last coding part). lol

Now I can adjust the shit out of the OL fuel tables without reservation.

Edit: @Kodename47 I've found a pretty big flaw after increase the fueling to address the lean spot using the OL fuel table. With my current tune and setup where it goes lean very low RPMs going full throttle, adding fuel to the lean portion of the rev range will cause the LTFT go up causing the rest of the range to go very rich. This will happen regardless where the afrs end up at around 2200rpm because of the difference between the target AFR and actual afrs.

Perhaps I should let the computer learn OL afr's a while longer and hopefully the computer will eventually drop the LTFT after the lean spot. But, by that logic I could just leave the OL fuel table alone and let the computer adjust to the lean spot. This is becoming a bigger headache than I anticipated. I did take several logs before and after the computer started increasing LTFT's in OL, but for some reason the files did not save. Maybe I ought to just get the afr's as close as I can by adjusting MAF scale and load limit tables and let the computer adjust itself to compensate. What do you think?

[Kodename47]

The ECU doesn't learn anything in open loop, hence the meaning of open loop

Something is causing a STFT somewhere that is being applied as a LTFT. It may well be transitional and due to CL to OL delays or similar.

[solidONE]

Originally Posted by Kodename47

The ECU doesn't learn anything in open loop, hence the meaning of open loop

Something is causing a STFT somewhere that is being applied as a LTFT. It may well be transitional and due to CL to CL delays or similar.

Is that right? I've seen in logs where the LTFT will drop at the upper range. For instance at wot LTFT will start at say 3% up till 5000rpm then drop to 1% to redline. At 5000rpm the maf voltages will have passed the CL range of up to 3.0v. Let me find a old log like that and I will add to this post later.

Edit: @Kodename47

Here's one where LTFT starts to drop at the beginning of the pull and at the upshift then raises back up at the end. 3rd to 4th gear upshift:
http://datazap.me/u/solidone/e85-tom...zoom=1651-1836

Most of them look like these. Probably something to do with the PI/DI ratios, is my guess:
http://datazap.me/u/solidone/stg1-fp...om=10003-10097

http://datazap.me/u/solidone/90amb-o...zoom=5305-5362

http://datazap.me/u/solidone/plm3-fp...zoom=5842-6081

http://datazap.me/u/solidone/plm85-2...zoom=4460-4688

If the computer is not "learning" then how/why is it making adjustments to LTFT under OL operation?

[Kodename47]

Originally Posted by solidONE

Is that right? I've seen in logs where the LTFT will drop at the upper range. For instance at wot LTFT will start at say 3% up till 5000rpm then drop to 1% to redline. At 5000rpm the maf voltages will have passed the CL range of up to 3.0v. Let me find a old log like that and I will add to this post later.

It has something to do with the Airflow learning ranges. These are the areas boundaries for setting LTFT.



It's possible you're in these ranges at some point when in CL. There may be DI ranges or mixed ranges that we don't yet know about. However the theory is that LTFT is set by repeated STFT. Since STFT can only be set in CL, therefore the LTFT cannot be influenced by open loop operation.

[solidONE]

Originally Posted by Kodename47

It has something to do with the Airflow learning ranges. These are the areas boundaries for setting LTFT.



It's possible you're in these ranges at some point when in CL. There may be DI ranges or mixed ranges that we don't yet know about. However the theory is that LTFT is set by repeated STFT. Since STFT can only be set in CL, therefore the LTFT cannot be influenced by open loop operation.

I see. I assumed that the computer was adjusting the LTFT to the differential between target afr and actual afr under OL operation, like a sort of coarse adjustment such as the IAM.

edit: looking at my old log with the different exhaust setup I can see that my new set up "should' have more potential in the top end. The maf voltage peak at 4.04v in 3rd gear with the old set up while my new setup will peak around 4.08v. Yet, my new setup peak WHPS are about the same as the old setup for some reason. There are more ponies hidden in there, I know it...

[phrosty]

I have logs with LTFT changing @ WOT, 7000rpm, with MAF over 4 volts. The most I've ever seen CL go to is around 3.1 volts. There's definitely something about it that we don't understand.

Actually, I've got my tune modified to have full DI all the way up to 7000, with 7200 being partial PI, so there's a good chance this is the result of PI kicking in.

[thambu19]

Originally Posted by phrosty

I have logs with LTFT changing @ WOT, 7000rpm, with MAF over 4 volts. The most I've ever seen CL go to is around 3.1 volts. There's definitely something about it that we don't understand.

Actually, I've got my tune modified to have full DI all the way up to 7000, with 7200 being partial PI, so there's a good chance this is the result of PI kicking in.

Isnt LTFT based on engine speed? I dont assume the LTFT to stay constant across all engine speeds. They will have cells containing ranges of engine speeds that will have the same LTFT and once the engine speed/load crosses the cell boundary it can have a different value. Correct me if I am wrong please.

[thambu19]

Originally Posted by solidONE

Alright, that makes a lot of sense. Thanks for the visuals! Makes it much easier for this lowly grease monkey *points to self* to understand (save for the last coding part). lol

Now I can adjust the shit out of the OL fuel tables without reservation.

Edit: @Kodename47 I've found a pretty big flaw after increase the fueling to address the lean spot using the OL fuel table. With my current tune and setup where it goes lean very low RPMs going full throttle, adding fuel to the lean portion of the rev range will cause the LTFT go up causing the rest of the range to go very rich. This will happen regardless where the afrs end up at around 2200rpm because of the difference between the target AFR and actual afrs.

Perhaps I should let the computer learn OL afr's a while longer and hopefully the computer will eventually drop the LTFT after the lean spot. But, by that logic I could just leave the OL fuel table alone and let the computer adjust to the lean spot. This is becoming a bigger headache than I anticipated. I did take several logs before and after the computer started increasing LTFT's in OL, but for some reason the files did not save. Maybe I ought to just get the afr's as close as I can by adjusting MAF scale and load limit tables and let the computer adjust itself to compensate. What do you think?

Have you messed with the cam timings? If you are running too much overlap there is no point looking at AFRs in the scavenging range since the O2 sensor is easily confused with the fresh air that is short circuiting the engine.

[thambu19]

Can someone tell me what are the loads a stock engine typically sees in terms of g/rev?

I still do not understand the g/rev concept. Is it same as volumetric efficiency meaning 1.0 = 100% VE? If that is the case why do we have numbers like 1.4 and 1.5 since I dont expect an NA engine to run at 150% VE.

[jvincent]

Originally Posted by thambu19

Can someone tell me what are the loads a stock engine typically sees in terms of g/rev?

Going WOT in 3rd gear my load starts of at about 0.8 at 2800 RPM and gets up to 1.3 at around 7000 RPM.

Cruising at 3200 RPM in 6th it's around 0.5.