Need help with understanding MAF adjustments.

[bink]

I too was a MAF follower.....yes I admit it. (I do believe it's a great sensor when recalibrated as needed)

I was very wrong .......HumpinSS/Dirk was very right.

There are a couple of ways to intuitively see the inherent inaccuracies of the MAF:

1.) The existance and utilization of the VE table.

2.) LTFTs and STFTs.

The MAF is an inexpensive, reliable sensor which enables GM to meet federal standards.

The really NEAT part of all this, for me, is how far tuning has come from the old days of spreadsheets and voodoo.
Thank you.... EVERYONE!!!!


joel

[Dirk Diggler]

Voodoo is right spreadsheets are the devil LOL

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TAquickness, contrary to the popular opinion, MAF is not the source of all evil
i seriously have problems being able to tell the difference between both modes, if i disable the SES light for SD operation. The only time where i can tell the difference is at the track (the one with turns) 'cause SD is a bit quicker to react to minute changes in throttle, which you can only feel while pushing it through a corner and trying to precisely feed it gas.
so in the vain of 'guns don't kill people--people kill people':
MAFs don't fuck up your tunes--people who don't tune MAFs fuck up their own tunes

There is a considerable difference in the twisties between SD and MAF - at least with my car.

[jfpilla]

I too was a MAF follower.....yes I admit it. (I do believe it's a great sensor when recalibrated as needed)

I was very wrong .......HumpinSS/Dirk was very right.

There are a couple of ways to intuitively see the inherent inaccuracies of the MAF:

1.) The existance and utilization of the VE table.

2.) LTFTs and STFTs.

The MAF is an inexpensive, reliable sensor which enables GM to meet federal standards.

The really NEAT part of all this, for me, is how far tuning has come from the old days of spreadsheets and voodoo.
Thank you.... EVERYONE!!!!


joel

Joel.
You are joking? Aren't you?
Joe

[bink]

Joel.
You are joking? Aren't you?
Joe

No, not joking.
I'm not sure what your questioning joe?
Maybe I'm not clearly stating my thoughts/opinion.

I used to think GM had mega dollars and therefore mega instruments to check/verify the MAF. That is to say the MAF, as GM scaled it, was at it's optimum - period.
As I followed threads by HumpinSS, TAQuickness, RedHardSupra, txhorns281, and the rest, I realised they were getting good results with Speed Density tuning. In fact HumpinSS told me many times that I should at least try it - try it you'll like it.

One day jfpilla (That's you!) puts up a post about the importance of accurate injector flow rates and the importance of known, quantitative values. Do you remember this?? Well, something went "Boing" in my brain - damn I hadn't thought about that!! Constants!
So over the course of a few weeks/months I look at countless factory tunes. I looked closely at the ASA tunes (Thanks Dave Farmer and Jess/wait4me) also - since I use the GTP/ASA injectors. Seems like the Injectors are constant and everthing else is tweaked or varible. Airmass Calcs , VE, LTFTs, STFTs, Idle Airflow Trims.........MAF.
We know, or can know accurate injector flow rates, fuel rail pressure and accurate AFR.
As I see it -> we develope the VE table in SD and then IF we want.... go back on the MAF. Scale the MAF so AFR is equal to Commanded and were good to go.
I think this is probably similar to GMs methods (I don't think they use EFILive though.... I bet they wish they could have!!). What I'm amazed by is the way GM was able to crutch the MAF at lower RPM...the aimass calcs/dynamic airflow.
I'm begining to ramble...I'll shut up!


I hope this makes sense.

joel

[jfpilla]

I too was a MAF follower.....yes I admit it. (I do believe it's a great sensor when recalibrated as needed)

I was very wrong .......HumpinSS/Dirk was very right.

There are a couple of ways to intuitively see the inherent inaccuracies of the MAF:

1.) The existance and utilization of the VE table.

2.) LTFTs and STFTs.

The MAF is an inexpensive, reliable sensor which enables GM to meet federal standards.

The really NEAT part of all this, for me, is how far tuning has come from the old days of spreadsheets and voodoo.
Thank you.... EVERYONE!!!!


joel

Joel,
Seems as if I upset you. Sorry if I did.
I was surprised that you see the existance of the VE table and Trims as proof of the MAF's inaccuracies.
The MAF is only a meter. It's part of a "system". It doesn't nor can it stand alone. It is meant to take up for the shortcomings of a MAP system.
Auto manufacturers would love to eliminate the cost of the air sensor, but have not quite succeeded. It's very complicated to make it work for all driving conditions and R&D is costly. The MAP system does not handle VE changes very well. Hence the MAF was developed, not the opposite. The MAF system is highly accurate for maintaining A/F ratios and GM's system is well respected. If I had a track only car I would get rid of the restriction. For a daily driver though, the meter is better in my opinion.
That's all I was referencing.
Regarding your answer. I agree with it. I like to do the MAF final tweak by getting my LTrims negative by way of the MAF and comparing the results with the Dynair Map.
Regards
Joe

[bink]

Joel,
Seems as if I upset you. Sorry if I did.
I was surprised that you see the existance of the VE table and Trims as proof of the MAF's inaccuracies.
Joe

No way am I upset .
(We never know intent or mood in these things - bummer :( ).
I look at the retention of an active VE table as a crutch for the MAF - if the MAF was accurate at lower RPM we wouldn't need the VE table and it's overlaid Fuel Trims. It's semantics I guess.

My overall point was the MAF is not perfect and it may need to be rescaled. At one point in time I did believe it was crazy to rescale the MAF - as it was designed/calibrated to function with the airmass calculations. Of course I no longer hold this to be true

Once my car is back together I'm going to try Closed Loop with the MAF, again. That was my original goal.....2+ (or has it been 3+) years ago!!!

Cheers,
joel

[johnsZ06]

The Misunderstood Airflow Fixture (MAF) is part of a large conspiracy perpetrated by the big three to make tuners pull out their hair and spend countless hours of arguing and debating on the Internet, it's purpose, function and usefulness. So far, I'd say it's working!

[redhardsupra]

to all the MAF haters: other than the 512g/sec limit and having actual physical presence in the path of air, what are you major issues with it? for a long time it was calibration, but we solved that. i know that's not great in low rpm yet, but i'm working on it. what else?

[johnsZ06]

to all the MAF haters: other than the 512g/sec limit and having actual physical presence in the path of air, what are you major issues with it? for a long time it was calibration, but we solved that. i know that's not great in low rpm yet, but i'm working on it. what else?

Can we get it in a color other than black?