Need help with understanding MAF adjustments.

[dfe1]

One of the "challenges" of MAF tuning is having the proper "tools" to get it right. As an example, some "high flow" air cleaner systems introduce vortexes in the intake tract that don't exist with a stock air cleaner. So, at any given throttle setting, how do you tell whether a MAF is reading laminar air flow, or a vortex induced by the air cleaner? The same situation may exist when an aggressive camshaft is installed. Reversion and other abnormal (compared to a stock system) intake flow characteristics may leave the mass air meter reading a vortex rather than laminar flow at various points. And these vortexes may change considerably depending on degree of throttle opening and engine load. So the question is, how do you determine what the MAF sensor is actually reading, and whether it's reading consistently at a particular flow rate? I'm not suggesting that it's impossible to make those determinations, only that most people won't spend the time, or don't have the tools to do it. As a result, many MAF tuners have become known as big wheels because they run in circles.

[jetblast]

i believe the pcms protocol for fueling is a weighted average of all the fueling tables, if and all the supporting systems are working properly, although some tables play a larger or smaller role in computing the final fuel for a given eng. but. above 4krpm the maf has a major role in fueling and more so than the ve table. also if you install a bigger cam, the shape of the maps will change, but no other table will change its shape more than the ve, especially the peak torque section of the map, the maf should also encrease but the basic curve should remain the same unless the track is modified, for example: removing the maf screen. suppose the maf fails at wot, the pcm must be set up so that there is enough fueling and less timing as a safety measure. if you zero out the ve table the eng. will not run. if you compare 2 stock tunes from two types of cars, each one having different intake track routing and different cams and injectors. you will see that the shape of the ve tables will be different and reflect that specific cam and the maf table will also be different but not in the same way, the change is more subtle. in the end having the correct balance is what its all about or somewhat close to it. just my humble opinion, i have only tuned and owned one muscle car since 04. so i'm probably wrong. still learning.

[dfe1]

i have only tuned and owned one muscle car since 04. so i'm probably wrong. still learning.

Quite the contrary, you're undoubtedly right. As has been stated previously, MAF readings are influenced by a variety of factors, and I think the real challenge is in finding a legitimate way to correct MAF readings after camshaft and intake tract changes are made. I think a lot of people cause themselves unnecessary problems because they change MAF tables, when the real problem is the data in the VE or IFR tables. In essence, they're correcting one error that was actually caused by another. At the end of the day, all that really matters is that the commanded and actual AFRs are close enough to be considered the same. So the question becomes, is it better to crutch the VE or IFR tables to compensate for errors in the MAF table or vice versa?

[redhardsupra]

if you wanna find out what's really going on with MAF, SD and tuning using a wideband, read this:
http://redhardsupra.blogspot.com/200...ss-models.html

[Bruce Melton]

TAQ and Marcin and all,

I think what we need to end up with here is an agreed upon MAF "dial in" procedure. There are a few short versions around and some refer to portions of the AutoVE tutorial but for me and others, I think, it is hard to know reference step by step procedure how and where to enter and how to exit the current AutoVE tut. which itself has changed, (thankfully).

B3605 setup in AutoVE should end up @ ~13:1 in what will end up in PE range I assume, and the sum of all the influences in RHS's math models should tune to the 14.7 and ~13 combination that can be tweaked.

After the AutoVE without MAF> MAF dial in> MAF re- enabling> then PE tweaking we seek a happy balanced tune where all the GM guru and tuner work yields smooth safe results. I hope that is what we all want what EFILive is all about.

Some of us are big MAF fans (for various reasons) and mother GM seems committed to them. I for one, feel better if I send a tuned car loose, into the climate extremes we suffer, knowing a MAF (preferably, a big new non restrictive MAF) is watching over the tune.

[jetblast]

if you wanna find out what's really going on with MAF, SD and tuning using a wideband, read this:
http://redhardsupra.blogspot.com/200...ss-models.html

that article seems to imply that dynamics of the operating range of a gasoline engine are infinite and so to arrive at an operating model as good as the gm, ford, chrysler guys when modding, would require using their testing facilities, and so therefore using their model as a reference point is worth some coin, coupled with fuel consumption {mpg} info. a reasonable tune for a modded eng. is then possible. so if you have two identical modded engs. with two different tunes one having a bit more bias towards the maf than the ve, if both have good starting, driveability, wot characteristics, and good satisfactory fuel consumption under various temps and altitudes than i would be satisfied, except for wot which if you go the the track being flexible can gain you a .1 or more on any given day. i'm just a beginer and my perception of how things work maybe wrong.

[redhardsupra]

this writeup says few things:
1. we finally know the exact models for airmass in both SD and MAF
2. know how to know how to convert one to the other
3. the only 'starting point' as far as airmass goes is fuel consumption. unfortunately this is the 'noisiest' airmass model we got, so it's gonna take some interesting math to get the junk out.

and to answer Bruce here...
From where I'm sitting, there's not much to agree on here. if you read my derivations, you know the steps that would go into the MAF calibrations:
1. go pure MAF mode
2. estimate airmass from fuel consumption
3. clean the data
4. convert airmass to airflow
5. fit 3rd order poly to the airflow estimations
6. use the fit to generate the calibration for points needed (since start/end/intervals change on different cars)

or, if you already have a perfect VE table, then just convert one airmass model to the other.

[joecar]

A "simple" matter of starting from the "least" number of "unknowns"...



...are there any other "banging" icons...

[hquick]

Lol! that's me in all of those Joe.
Unknowns????...What are 'KNOWNS"?

[jetblast]

i dont mean to undermine some of the great thinkers here. i have no doubt that my tune is not perfect, but i'm satisfied that i have great fuel economy, i can idle for long periods of time and not foul my plugs, cold and hot starts are normal, winter or summer, and wot, the most fun of all, is giving me great results. now if i could just break 10s!