Tuning Notes by WeathermanShawn

[mr.prick]

I gotcha.
Excel is useful but I just make calc_pids for everything even offsets and filters.
For me that's easier.

[joecar]

I'm still catching up on the reading and digesting and checking the units (after some leaky roof repairs... we're getting the whole years worth of rain in 4 days here in So Cal... ).

Any place/time you use the MAF to correct something means you have reason to believe that the MAF table is already calibrated... this may or may not be a valid assumption... oh, I see, you're using LTFT's to correct thwe MAF table... (my roof is still distracting me...)

Anything that saves time-consuming steps is good......we all don't have lots of time on our hands.

If you see actual EQR matching commanded EQR then the method has validity... that can't be refuted.

No, this is good reading, it makes me go back over Marcin's papers.

Please do continue...

BTW: I like the good intelligent discussion... on other forums this would have degenerated into a closed-minded pissing match about MAF's or something. Thanks to all.

[joecar]

Shawn,

Marcin is not being hostile... he is being devil's advocate, he brings up things to make you rethink and possibly from another angle...

[joecar]

...

You simply make a run..log your LTFT's vs MAF Frequency..then cut and paste the LTFT % correction vs MAF Frequency. That gives you a nearly perfect MAF Calibration Table. You then do another log and utilize the EFILive CALC.VE pid and using the EFILive MAP function, you apply the data to a RPM vs MAP Table. You then cut and paste that directly to your VE Table.

Your VE Airflow and MAF Airflow then match perfectly. You then log another run..log your AFR's at Stoich and WOT..and it all works.

...

That is it in a nutshell, very simple, can be done in 2 runs with some thought out driving pattern...
one run to correct both MAF and VE tables, a second run to verify AFR's with wideband.

that is very simple and saves a lot of time, and uses a wideband only for verifying the result.

Edit: see red ink.

[WeathermanShawn]

I'm still catching up on the reading and digesting and checking the units (after some leaky roof repairs... we're getting the whole years worth of rain in 4 days here in So Cal... ).

Any place/time you use the MAF to correct something means you have reason to believe that the MAF table is already calibrated... this may or may not be a valid assumption.

Anything that saves time-consuming steps is good......we all don't have lots of time on our hands.

No, this is good reading, it makes me go back over Marcin's papers.

Please do continue...

BTW: I like the good intelligent discussion... on other forums this would have degenerated into a closed-minded pissing match about MAF's or something. Thanks to all.

Thanks Joecar.

Any place/time you use the MAF to correct something means you have reason to believe that the MAF table is already calibrated... this may or may not be a valid assumption.

My method is to use the narrowband O2's and LTFT's to 'calibrate the MAF. If after logging a LTFT MAF Calibration and simultaneously logging your wideband..say you come up with an average of 14.63 AFR's for all non-PE Modes, and you have an accurate Commanded Fuel for your AFR's. Why would that not be an accurate method? Both MAF and VE Table airflows match, and all you RPM/MAP's show perfect stoich values during non-PE modes..and WOT AFR's are perfect.

The end result appears to valid. And the Airflow models are virtually identical.

[joecar]

I use the old meaning of the word "hack" where it means that someone who knows there stuff inside-out can make a simpler code edit to make it work properly...

Ok, the method of calculate-IFR, correct-VE, correct-MAF eliminates several assumptions and is a more-scientific approach... a wideband is required... and this approach is very time consuming.

The LTFT-correct-MAF and calculate-VE approach is very quick/simple and doesn't require a wideband other than to see the results (did me comprehension skills support me correctly...? )... even tho this is simple/quick, this might not necessarily be for beginners since the user has to understand some of the interactions going on.

[WeathermanShawn]

Shawn,

Marcin is not being hostile... he is being devil's advocate, he brings up things to make you rethink and possibly from another angle...

I think Marcin just needs to take the plunge and publish his own Tuning Tutorial.

[joecar]

...

My method (shortcut) is to use the narrowband O2's and LTFT's to 'calibrate the MAF. Maybe my question would be thiis. If after logging a LTFT MAF Calibration and simultaneously logging your wideband..say you come up with an average of 14.63 AFR's for all non-PE Modes, and you have an accurate Commanded Fuel for your AFR's.

Why would that not be an accurate method? Both MAF and VE Table airflows match, and all you RPM/MAP's show perfect stoich values during non-PE modes..and WOT AFR's are perfect.
...

If the wideband shows actual EQR matching commanded EQR (i.e. BEN is at 1.00) then like 5.7ute said this is valid...

the test is then to see what the BEN's are for the boundary cases.

[WeathermanShawn]

If the wideband shows actual EQR matching commanded EQR (i.e. BEN is at 1.00) then like 5.7ute said this is valid...

the test is then to see what the BEN's are for the boundary cases.

Granted..some of the lower Idle Rpm's and MAPs < 25 kPa do not always meet Commanded AFR's. I have had to lower some of my MAF produced VE Table for Idle (~10-15% less fuel), and reduce the Airflow for the 15-25 kPa for the 1200-1600 Rpm's (~10-15%).

[redhardsupra]

Shawn, you're confusing 'combative' with 'scrutiny.' If you say something wrong, I will point it out. Besides, I wasn't calling you a hack, but the tuningschool guys. So unless you're related to them, I don't think your outrage is applicable. I'm not the only guy that tries to approach life with logic and science, I just found this and it made me think of you: http://scienceblogs.com/dotphysics/2...e_doing_it.php

If all you want to do is remap MAF's airflow numbers to SD axis and then calculate VE out of it, I've had that done in '06. Nothing new here. Also, it doesn't solve any other problems inherent to the BEN-based methods:
1. proper attribution--this is a big one, with the standard approach, you attribute ALL changes in airflow to ONE cause. If you're calibrating MAF this way, you end up with all the errors 'built into' the MAF calibration. If you do it on VE table, then the errors are all attributed to VE numbers. What if that's not it? What if it was the temperature? How about fuel delivery imprecisions? Sensor miscalibration? you cannot blame all errors on one arbitrary calibration, that's severly oversimplifying the problem. You must split all the pieces properly, account for pressure, temps, and then see how much error is left, and that's MAYBE something we could attribute to VE table.
2. Accounting for temps is hugely complicated in the GM scheme of things. I have it partially solved, and it's fantastically convoluted, and it takes some gnarly math to get anywhere proper solution.

so no, there is no easy step-by-step solution. that's why i didnt make one. not because i'm lazy, not because i dont like to write, it's because i think it would be spreading misinformation, and i refuse to be responsible for that.