Challenge to EFILive Tuning Concept:

[WeathermanShawn]

First, my "challenge" is meant in the utmost respect, and in the spirit of not only accelerating my own learning curve, but also those other users who obviously struggle with the same aspects of the more intricate concepts involved in the AUTOVE, EFILive tuning concepts. First off, I don't possess an engineering degree, but as a Meteorologist I do have a fundamental understanding of the properties of thermodynamics, air density, and airflow.

You would be surprised at examples of where the ideal gas law, while accurate in theory, has many pitfalls as it concerns to practical applications. I.E., drive through a significant temperature inversion and watch the dramatic changes in air density, and watch your tune go through some erratic fueling changes.

So, here is my question. I live in a state (Colorado), where elevation, air density, emissions etc, are ultimately going to require me to do the following:

1.) I have done the AutoVe (OLSD). I have also done the AutoVE (OLMAF).
2.) Due to the above mentioned limitations I must adjust to, here are my tuning requirements.

A). I will be running MAF.
B). I will be going back to closed loop utilizing narrow-band O2 readings, trims etc.

Bottom Line: I have spent a good 12 hours searching both LS1tech.com, and EFILive Forums. On LS1tech.com, doing a search of "MAF" brings up 112 pages of numerous opinions, some objective, but a lot highly subjective.

Respectfully, can anyone give as precise of a successful methodology to tune your car for exactly the way that you will be actually running it? The methodology of AutoVETune, without MAF, and then re-introducing a new calibrated MAF Table back into the VE (SD) calculations, seems to lack a precise mathematical formula to actually substantiate how this blend will actually precisely give you a consistent and accurate AFR.

Proportional MAF BENS, then no proven and precise method to combine VE (SD) and MAF, really makes me question what we are really after. For myself and apparently for many others, we just want to maintain a target AFR, that still conforms to running a car in closed loop with a MAF, and narrow band output.

Is there any proven method to tune your car to target a AFR under the parameters I mentioned above? Again, I acknowledge I am a 'one-post' guy. I am missing something, or I am just expressing what others of countless users must also think. I mean absolutely no disrespect to EFILive, the users of this board. Do I have a point?

So please don't react as this being a negative criticism. Just answer as frankly as possible. Can I command exactly the AFR I want, using Closed loop, O2 feedback., MAF, and SD parameters.

I appreciate the users taking the time to evaluate my perspective, and would appreciate any constructive and educational answers.

[TAQuickness]

In OLSD you will need to spend more time with the PCM's temperature compensation parameters

In OLMAF, the nature of the MAF sensors compensates for the changes in air density

CL operation compensates for slack in the tune and physical defects (i.e. dirty MAF).

[TFZ_Z06]

In OLSD you will need to spend more time with the PCM's temperature compensation parameters

In OLMAF, the nature of the MAF sensors compensates for the changes in air density

CL operation compensates for slack in the tune and physical defects (i.e. dirty MAF).

I have often thought that we should complete VE and then correct to STP or some avg temp/pressure based on the area we live in.

[Ryan]

Hi Shawn,

I too am one of those "one-post" guys, but I thought I'd chime in. First off, it is important to note that the ideal gas law is just that--a law for ideal gases. These don't really exist, although the Noble gases come close and the IGL pretty accurately defines the way they behave in most conditions.

We do have other models that can describe the behavior of density
Now, if you have not already, I recommend reading RedHardSupra's blog (http://redhardsupra.blogspot.com/); there is a lot to learn from that will give you a better understanding of what should be your goal as a tuner.

I am not so much in favor of using the "AutoVE/AutoMAF" method for tuning the MAF as the curve is described by a third-order polynomial and not just random values. If you can gather enough data, you can fit a new polynomial to match and make a new curve.

The PCM blends inputs from the MAF and VE table with a few other factors. From what I've read, the MAF is the most dominant factor in calculating air mass, but if either of the tables describing sensor input are wrong, it won't work correctly. I would expect that in closed-loop operation, the air mass is calculated in the same way as open-loop, but with the fuel trims adjusting the final calculated mass.

Provided you have all working sensors, current methodology says that you should go through the AutoVE process, then AutoMAF, then put the engine back into closed loop mode. At this point, you could use a wideband O2 sensor to monitor your narrowband switch points at stoich and adjust them accordingly.



Can I command exactly the AFR I want, using Closed loop, O2 feedback., MAF, and SD parameters.

The point of closed-loop operating is that it attempts to maintain a constant AFR close to the stoichiometric ratio for the fuel. I suppose you could do this by fooling the switch points while monitoring with a wideband, but the narrowband sensors are designed to function right around stoich, hence the name. All else correct, you can use PE modifiers to get the commanded AFR you want at "non-steady" conditions.

[Delco]

First, my "challenge" is meant in the utmost respect, and in the spirit of not only accelerating my own learning curve, but also those other users who obviously struggle with the same aspects of the more intricate concepts involved in the AUTOVE, EFILive tuning concepts.

First off, I don't possess an engineering degree, but as a Meteorologist I do have a fundamental understanding of the properties of thermodynamics, air density, and airflow.

You would be surprised at examples of where the ideal gas law, while accurate in theory, has many pitfalls as it concerns to practical applications. I.E., drive through a significant temperature inversion and watch the dramatic changes in air density, and watch your tune go through some erratic fueling changes.

So, here is my question. I live in a state (Colorado), where elevation, air density, emissions etc, are ultimately going to require me to do the following:

1.) I have done the AutoVe (OLSD). I have also done the AutoVE (OLMAF).
2.) Due to the above mentioned limitations I must adjust to, here are my tuning requirements.

A). I will be running MAF.
B). I will be going back to closed loop utilizing narrow-band O2 readings, trims etc.

Bottom Line: I have spent a good 12 hours searching both LS1tech.com, and EFILive Forums. On LS1tech.com, doing a search of "MAF" brings up 112 pages of numerous opinions, some objective, but a lot highly subjective.

Respectfully, can anyone give as precise of a successful methodology to tune your car for exactly the way that you will be actually running it?

The methodology of AutoVETune, without MAF, and then re-introducing a new calibrated MAF Table back into the VE (SD) calculations, seems to lack a precise mathematical formula to actually substantiate how this blend will actually precisely give you a consistent and accurate AFR.

Proportional MAF BENS, then no proven and precise method to combine VE (SD) and MAF, really makes me question what we are really after.

For myself and apparently for many others, we just want to maintain a target AFR, that still conforms to running a car in closed loop with a MAF, and narrow band output.

Is there any proven method to tune your car to target a AFR under the parameters I mentioned above?

Again, I acknowledge I am a 'one-post' guy. I am missing something, or I am just expessing what others of countless users must also think.

I mean absolutely no disrespect to EFILive, the users of this board. Do I have a point?

So please don't react as this being a negative criticism. Just answer as frankly as possible. Can I command exactly the AFR I want, using Closed loop, O2 feedback., MAF, and SD parameters.

I appreciate the users taking the time to evaluate my perspective, and would appreciate any constructive and educational answers.

Respectfully..

..WeathermanShawn..


Yes you can but remember we dont live in a ideal world where you have total control of the atmosperic conditions.

When I did OEM engine calibrations to do the base calibrations we used to have the engine in a fully climate controlled dyno cell , then a full range of tuning was undertaken at different atmospheric pressure conditions , temperature and humidity with only changine one variable at a time until we had a optimium tune that satisfied all the requirements of power , economy , emissions , durabilty and NHV , this took a team of 8 techs running the dyno 24/7 approx 1 month to get in the ballpark , make a minor change like filter housing or intake/exhaust system and the whole regime would start again.

Can you do this on the road and a rolling road - the answer is yes BUT expect to take 4-5 years to get the tune nailed to that level ( and remebering you are only looking at 3% of the possible tuning variables in most tuning tools on the market ) huge amounts of logging and analysing the data , even then you are most likely only to optimise for power and economy

Do the best you can , play with the tune daily and enjoy the experience knowing like teh real world nothing will ever be perfect.

[Ryan]

When I did OEM engine calibrations to do the base calibrations we used to have the engine in a fully climate controlled dyno cell , then a full range of tuning was undertaken at different atmospheric pressure conditions , temperature and humidity with only changine one variable at a time until we had a optimium tune that satisfied all the requirements of power , economy , emissions , durabilty and NHV , this took a team of 8 techs running the dyno 24/7 approx 1 month to get in the ballpark , make a minor change like filter housing or intake/exhaust system and the whole regime would start again.

Can you elaborate on this any more? I would really like to know more about the methods utilized by the factory. :)

[WeathermanShawn]

First, let me thank everyone for their replies.

I am always amazed by the general expertise exhibited by many members on this board.

Ryan and Delco, I was especially intrigued by many of your observations. (not to exclude you TAQuickness). I appreciate your honesty in describing the impractically of obtaining a "perfect" tune outside of a climate-controlled dyno lab.

I was beginning to question the practicality of my "open-road' tuning methods. Utilizing some fairly deserted wide-open roads in Eastern Colorado. Not the safest "dyno lab", and hard to maintain temperature and elevation data in a consistent manner.

On the subject of "AutoVE/AutoMAF. I also have read many of "RedhardSupra's" readings and blog. Smart person..I'm still a little behind in my learning curve vs his, so I have have some more learning to do.

It is perplexing to solve VE (SD) without MAF, then reintroduce the MAF variable and really expect a precise calibration. Especially in associating MAF HZ, with a particular AFR. Thats my hang-up. I can understand calibrating MAF HZ to a particular MAF flow..But applying AFR Ben's from MAF frequencies, will take me a little longer to fully comprehend.

So the bottom line is this. Is it a more reliable method to calibrate GM.MAFFREQ vs GM.DYNAIR (In OLSD)? I've seen and read all the debates, but is it a proven and reliable method?

Is simply matching the SD DYNAIR and matching it perfectly to MAF FREQ sound science?

As you all have stated, nothing is perfect and I that I understand. Ultimately tuning VE with all the parameters included would be the ultimate. I understand as a Meteorologist, thats virtually impossible to do.

Thanks again. I appreciate all the comments, and if anyone else feels like adding to the conversation, please do.

Remember, I am wanting to make it as simple and practicable as possible.

Commanded AFR's with VE's tuned in, MAF, and closed loop capability.

Thanks again.

..WeathermanShawn..

So the

[Ryan]

It is perplexing to solve VE (SD) without MAF, then reintroduce the MAF variable and really expect a precise calibration. Especially in associating MAF HZ, with a particular AFR. Thats my hang-up. I can understand calibrating MAF HZ to a particular MAF flow..But applying AFR Ben's from MAF frequencies, will take me a little longer to fully comprehend.

Solving for VE without the MAF seems odd, since the MAF seems to be the dominant influence in airflow calculations when in normal operation; the VE table (I think) was intended for transient throttle conditions.

With the AutoMAF method, we aren't associating MAF frequency with an AFR. The AFR is just a ratio between air mass (or airflow) and fuel mass (or fuel flow). Ideally, we are able to monitor fuel flow through our scanned PIDs, which means calculating the airflow is as simple as multiplying the two.

The BENs are simply a ratio of the observed and commanded AFRs. By multiplying our VE table (or MAF curve) by the BEN factors, we are ideally correcting our values.


So the bottom line is this. Is it a more reliable method to calibrate GM.MAFFREQ vs GM.DYNAIR (In OLSD)? I've seen and read all the debates, but is it a proven and reliable method?

If I am understanding you correctly, you are asking if it is possible to log MAF frequency along with dynamic airflow from SD calculations and plot the latter onto the MAF curve? If so, I suppose that is possible, but it will require you to have an accurate VE table. I am not sure if this is the "correct" way of doing things, because if the VE table was meant to compensate for transient conditions and the MAF was intended for steady state operation, we are doing things backwards by using AutoVE to recreate a VE table under steady conditions (which you are doing if you are applying the filter recommended by the tutorial).

[WeathermanShawn]

Ryan:

Thanks for your reply and clarification.

I think at this point I should just continue further logging and refining the parameters of MAF calibration as described in the AutoMaf "tutorials".

I can always separately log MAFFREq vs SGM.DYNAIR (while in OLSD mode) and make some comparisons.

I think you along with other users recognize an inherent difficulty in computing a VE curve (SD..excluding MAF airflow), and then separately re-introducing MAF airflow and it's contribution to fueling.

While RedHardSupra and others provide some brilliant insight into the fact that SD computations can be done without MAF, its pretty vague on the exact proportions of the MAF contribution airflow and it's precise effect on the resulting fueling changes.

Some discussions I've read insist that the MAF BEN's calibrations factors are not a one-to-one ratio. Some suggest 1/3-1/2 BEN's. Thats suggest to me that the methodology lacks a precision and accuracy to make many users confident of the results.

So, my point is not to be construed as argumentative. It is simply respectfully challenging the concept of two differing methods of calculating fuel based on two methods of determining airflow. One which excludes MAF, and then the other re-introducing a MAF airflow which by all accounts still utilizes airflow computations based on some degree by your original AutoVE (SD) .

Perhaps I am just discovering what many others have already comprehended. My main point is that as a relatively new user to EFILive and tuning, and from numerous searches on MAf calibrations, the 112 pages of search-related "MAF" questions on LS1Tech.com, and the general perception that very few people have a good grasp on this concept.

Since confusion is not just limited to people with little background in science or engineering, I think the "problem" is that perhaps any tuning method is not just a one or two step procedure (remains me of calculus).

I appreciate all the input. I humbly acknowledge I still have a lot to learn, and in no way am I giving up or criticizing the amazing capabilities of advancing tuning methods such as EFILive.

Does anyone acknowledge that if the ability to tune a car as a system (one or two step tuning)..I.E. tuning VE's, MAF, closed loop, etc existed, you could probably advance tuning theory in such a way that many more people would avail themselves of it, and the developer would probably be rich beyond means.

My conclusion is fairly factual. I tuned OLSD, tuned OLMAF, and when I combined the two to tune the car in the way I intended to always run it (Closed Loop), the combined total integration of the tuning methods didn't quite equal the results expected from the many hours put into it.

Again, I am just giving objective feedback with no disrespect to the product. Promise, I won't give up trying, but makes me wonder how people less motivated stick with a fairly complex concept and deal with the various modifiers and parameters.

Just reminds me of Calculus. Eventually got it, but lost half our class by the end of the course.

Anybody else feel the same, or have some constructive ideas on a more 'total system' approach?

Sorry for the length of the post. Just trying to learn.

Respectfully

..WeathermanShawn..

[TAQuickness]

$0.02 - Thinking of the air mass model in an LS1 F-Bod application...

The PCM incorperates 2 air mass models, VE and MAF


Under factory calibration:
The PCM will use a blend of VE & MAF tables under 4000 RPM. The more steady state the condition, and/or as the engine speed moves closer to 4000 RPM, the more bias to the MAF
Above 4000 RPM, the MAF is used exclusively as the air mass model
Under P0101, P0102, P0103, or any other MAF failure, the PCM will use the VE table exclusively as the air mass modelWe also know that in OEM trim the MAF is not functioning in an ideal installation - hence the screen and air foils.

Knowing the basic PCM operation regarding VE and MAF, we utilize the VE table as the base air mass model. Once we have calibrated the VE table, we now have a known control constant to base our MAF tuning efforts on.

I do believe it's possible to use the MAF as the base air mass model then tune the VE. (i.e. disable use of the VE table, calibrate MAF, enable VE table and use AutoVE to compensate the differences). Keep in mind though:

When a MAP sensor fails, the PCM does not resort to the MAF table.
In the event of a MAF failure, the PCM resorts to the VE table (in this case would be tuned to compesate a MAF).

[TAQuickness]

I've often wondered why you would use a 1/2, 1/3, or 1/4 application of a BEN factor. I've not personally run into this problem so I've concluded that something else is off in their tune.

[redhardsupra]

Shawn, you got PM...

[Ryan]

TAQuickness:
The reason I have mentioned the MAF dominance in the air mass model was because of what I read here (http://www.hptuners.com/forum/showthread.php?t=2359) (note! "other" forum).


A very important calculation the VCM must make to ensure correct fuel mixtures under all driving conditions is the dynamic airmass calculation. This is the main calculation the VCM uses to determine how much air it should use for the Base Fuel Calculation (Inj PW). The airmass calculation is not simple and uses various combo's of MAF and SD inputs depending on engine operating conditions such as current engine RPM. It may also make decisions based on whether the engine is in a steady load state (steady MAP) or unsteady load state (Unsteady MAP). Note, that these thresholds change with RPM and MAP. eg. at higher RPM or high MAP readings you have more leeway before the VCM decides that you have an Unsteady MAP condition. This unsteady MAP defintion is basically there to decide if a throttle transient has occured (or other) ie. the MAF input is known not to be accurate under these operating conditions.

Under normal conditions (ie. all sensors working properly) in the code i'm looking at it is like this:
(caveat: many of these thresholds may vary between code revs and vehicle type)

RPM > 4000
----------
*trust MAF completely and ignore SD calcs (apart from MAF sanity checking purposes)

RPM < 4000
----------
*if RPM < 2400 and MAP < 84 kPa then
* * *Steady MAP threshold = 0.0 kPa
*else
* * *Steady MAP threshold = 0.8 kPa

*If (SteadyMAP) then
* * *Calculate MAFAirmass/SDAirmass ratio (used for Unsteady MAP operation)
* * *Correction Airmass = MAF Airmass (filtered)
*else
* * *Correction Airmass = SD Airmass x MAF/SD Airmass Ratio (calculated during Steady MAP conditions)

*Transient Corrected Airmass = previous Final Airmass + proportion of Correction Airmass

*Final Airmass = fn(MAF Airflow, previous MAF Airflow, prev 3 MAP readings, prev 3 TPS readings,
Transient Corrected Airmass)

*There are 9 coefficents to this filter (and a total of up to 16 diffent sets of coefficients depending on operating conditions). It is worth noting that the previous value is weighted heaviest followed by the 2 MAF terms, so MAF dominates IMHO).

*There are also a number of checks at the end to make sure things do not exceed certain limits


To summarise:
1. High RPM behavior is totally based on MAF
2. Mid RPM behaviour has an allowance on Steady MAP behaviour before it switches to Unsteady MAP
3. Low RPM behaviour (where the bulk of the fuel cells are) is dictated by unsteady MAP behaviour that is still mostly dominated by the MAF input with small tweaking from SD)

If the VCM decides that a throttle transient has occured (unsteady MAP), the airflow incorporates a "correction" from the SD calculations. This value is the SD calulated airmass multiplied by the previous ratio of measured MAF airmass to calculated SD airmass (this normalises it, since you are worried about the transient deviation from MAF airmass only). The way i understand it is this, imagine you are cruising (MAP is steady), you have a decent vacuum in the manifold and you change the throttle position quickly. Air rushes into the manifold to service the change in air demands from the engine itself but also to try and fill the vacuum. The result is that the MAF reads higher than it should at that point in time (spikes). This is more pronounced at low RPM where the engine airflow is smaller and the relative proportion of extra airflow due to filling vacuum is higher, also the MAF is known to be more inaccurate at lower RPM and more non uniform airflow. IMHO, the SD correction is to account for filling and emptying of the manifold during throttle transients and also to smooth the MAF's spikyness at lower RPMs.

The bottom line is that if the engine is at a steady load state or operating at high RPM then the airflow is 100% based on the MAF once you get thru all the filters and calculations. And the SD calcs only get used for transients and smoothing lower speed operation.

At no stage does the MAF get ignored completely in these calcs (the dominating terms of the main filter calc are always MAF based).

Now, why is it that we can have a decent approximation of the airflow (determined by the wideband reading) when using the original MAF/VE setup, i.e. our WB reading is close to commanded, but maybe not dead-on, but when we disable the MAF, tune the VE table alone, and re-enable the MAF, the car instantly swings lean?

It would seem to me that we are doing things backwards by trying to make the dominant factor conform to the non-dominant factor, that is, if what Chris posted some time ago is correct.

I don't have any additional explanation or ideas; these are just some things that seem inconsistent to me and I am curious if anyone can offer an explanation. :)

[WeathermanShawn]

Yes, you guys have brought up the Million Dollar Question!.

Sometimes I have spent over a year to understand a Meteorological formula, utilizing the classic scientific method of reducing as many other variables that may bias the result.

But occasionally I gain an truer understanding when I actually include all the variables that effect an outcome.

No easy answers here. I just think if you could tune SD's along with MAF, O2's etc, you would have the ultimate tuning program.

Thanks for the inputs. RedHardSupra has PM'ed me, so I interested in hearing his thoughts. If at some point he wants to share them or further enlighten us to his viewpoints, I'll leave them up to him.

Did not necessarily want to make my first series of posts so technical, but so far all the responses have really enhanced my understanding of the tuning process.

Thanks again. If anyone else wants to share their viewpoints, please do.

..WeathermanShawn..

[SSpdDmon]

I might catch some sh!t for this, but oh well....

http://www.ls1tech.com/forums/showthread.php?t=733929

There's some discussion in that link that refers to what I tired once upon a time. I'll try to summarize. A different way that I used to tune one of my LS1s was to reverse the process. Typically, the tutorials tell you to set IFR, tune VE, and then tune the MAF. I put the spin on it that you set the MAF (already done from the factory assuming you have a stock/screened unit), tune the IFR, and then tune the VE last. The way I did that was to drop the B0120 threshold to something low (i.e. 400rpm). This should kill the VE's influence. Then, I made a map in the scanner that looked like the IFR table and logged my AFR vs. my WBO2. Based on the *filtered* results, I adjusted the IFR table (down for more fuel and up for less). Once I finished with the IFR table, I killed the MAF and restored the B0120 value back to factory (4,000rpm). Then, I dialed in the VE using the new-found IFR table. After several rinses/repeats, it was acceptable. The last step was to restore the MAF and let 'er rip. I sold the car with this tune in it and never heard a complaint from the new owner.

The whole point of me doing this was to try something new and learn from it. I'm not saying this is the best way or that it's more right than any other way. But, it was fun to experiment with something new and see what results it yielded me. :)

[redhardsupra]

allow me to enumerate the reasons why you're wrong:
1. MAF calibration changes with physical changes in the intake tract. unless you left your intake COMPLETELY stock, you cannot assume that MAF calibration is correct.
2. 'tuning your IFR' is a nice way of saying 'fudging numbers for a fueling model I dont fully understand.' Injector characteristics are physical constants for which calibrations can be obtained only by empirical testing and it's best left to the manufacturers. The only aspect of injector tuning you should be touching is adjusting IFR based on your actual fuel pressure.
3. by going pure MAF, you're simplifying a system that was not intended to be that simple. MAF does not have enough resolution at lower airflows to be used as the sole airmass estimator. Also, it requires steady airflow which is hard to get by driving around.
4. VE tuning as we know it so far is incomplete, as it assumes perfect TEMP estimation model calibration values, which they're not unless again, you kept your hardware stock.

new ideas are welcome. you can drive your car with your feet, but it doesn't make it a good idea.

[WeathermanShawn]

SSpdDmon:

Thanks for the response:

You should not apologize for 'thinking out of the box'.

That is a very intriguing angle I had not thought of.

I will attempt to make this discussion as non-argumentative as possible.

Just the fact that you as an experienced car owner and tuner is experimenting says a lot. Not only from a learning perspective, but perhaps you also recognize the VE, then MAF, etc., is not a flawless and perfect system.

I know the differing theories and tuning methods bring out a lot of passionate and well-defended arguments.

I appreciate all the viewpoints. From my perspective, keeping a nice constant AFR (the one I want), keeping the MAF, keeping the O2's, etc., has been a challenge.

However after reading the various posts and re-energizing over the weekend, I continued to go through the MAF calibration as described in the tutorials.

Luckily, the calibrations were within 5%, so I seem to have reached some success. I left the MAF threshold at 4000rpm's, and just put it back to closed loop, etc. Re-enabled everything.

To do this, I went back to stock MAF, stock bellows, and resealed the airbox (free-air mod).

Previously I had attempted the various methods of lowering the MAF threshold down to 400rpm, keeping it open loop, etc.

That just didn't work well for me. Going back to 4000 rpm MAF threshold and returning almost my entire intake tract back to stock, may have done the trick.

Again, appreciate all the responses. Yes, this takes a lot of persistence and and patience. Feel free to continue the conversation. I'm sure there will be a few more issues, but I am getting some success now.

Thanks again.

..WeathermanShawn..

[SSpdDmon]

allow me to enumerate the reasons why you're wrong:
1. MAF calibration changes with physical changes in the intake tract. unless you left your intake COMPLETELY stock, you cannot assume that MAF calibration is correct.
2. 'tuning your IFR' is a nice way of saying 'fudging numbers for a fueling model I dont fully understand.' Injector characteristics are physical constants for which calibrations can be obtained only by empirical testing and it's best left to the manufacturers. The only aspect of injector tuning you should be touching is adjusting IFR based on your actual fuel pressure.
3. by going pure MAF, you're simplifying a system that was not intended to be that simple. MAF does not have enough resolution at lower airflows to be used as the sole airmass estimator. Also, it requires steady airflow which is hard to get by driving around.
4. VE tuning as we know it so far is incomplete, as it assumes perfect TEMP estimation model calibration values, which they're not unless again, you kept your hardware stock.

new ideas are welcome. you can drive your car with your feet, but it doesn't make it a good idea.
...and I still say both ways are equally wrong based on my understanding that we don't have complete control over all of the tables that relate to fueling. So in a sense, we are fudging something one way or the other.

The problem I see with fudging the MAF table is the effects it has on perceived load. In other words, increase your MAF values >10% and you're going to shift over 2 or 3 cells in the timing tables....autos are going to generate different line pressures...and whatever else that is load-referenced will be off as well.

Your argument that changes in the intake tract are the cause for needing a dramatic recal is not constant in my experience – especially on a screened unit. I say this because I have recal'd MAFs (per the AutoVE tutorial) on a stock internals LS1 as well as an LS1 with heads/cam, where both cars had the same intake tract setup. Yet the H/C car required a much, much greater increase in airflow numbers as you moved up the curve. At the point of measure, both setups were identical and yet they were so different when you saw >6,000Hz worth of smooth, recorded airflow. Why?

I give you mad props for trying to take the time to model everything out mathematically. I don’t doubt the skill and knowledge it takes to do that. I do however have a bit of a business sense kicking in here when I refer to the K.I.S.S. theory (Keep It Simple, Stupid). Recognizing that both ways aren’t 100% accurate given the limitations we face, it’s up to us to pick the lesser of the two evils and go with what works. I believe the way I mentioned is a lesser of two evils for the reasons mentioned above. Does this mean I’ll discontinue using both ways? No. I won’t give up one of the ways because it’s been the general consensus of “x” number of people on the internet (of all places) that believe it’s the only right way to do it though. I understand how you feel about the methods you choose and all I ask is that you do the same for me… :)

[WeathermanShawn]

SSpdDmon:

You make quite a compelling argument!

Especially on the shifting of the timing tables as you make changes with the MAF calibration. Obviously noted it when I reviewed my logs, but you added a significant clarification to what was happening.

I re-read your thread you mentioned in your previous post (LS1Tech.com). Very interesting debate.

I think you are on to something in the concept of 'keep it simple'. I also admire the powers of higher mathematical theory and application, but if you are the only one who understands it and can not bring it down to the core basic principles, its a lonely world.

If one could successfully write the book on tuning and present it in such a way that many people could do it in four hours or less, that would be a tremendous accomplishment.

Fuel, air, and spark.

I don't anticipate tuning to be my new full-time hobby. I just took it on as a personal challenge, and 100 hours later I ponder how it could be done easier.

Thanks for your comments. I am now working on the idle (following your tutorials). At least I can now successfully idle at 800rpm, warm starts and all! Your tips are what saved me..

Thanks again.

..WeathermanShawn..

[TAQuickness]

Given a MAF is not installed with 10x diameter straight pipe fore and aft, ANYTHING, that changes the flow characteristics would mandate a recalibration of the MAF table. Granted, some mods will yeild more significant change to the curve than others and stock MAFs with screens and airfoils will be less prone to significant change to the curve.

By back calculating air mass basis measured AFR and fuel flow an accurate MAF curve should be do able.

So to prove this concept, who wants to donate a stock 85mm screened MAF?