Leave the MAF alone?

[johnsZ06]

The thread over on "Tech" got me thinking. Does anyone tune just the VE and leave the stock MAF settings alone?

I kind of agree that if a MAF is calibrated it should report exactly how much air flows through it regardless of the type of intake you are running. I understand reversion can screw with these readings but besides that, should it's calibration be messed with? Why not just tune the VE and forget the MAF?

I'm sure has been beat to death but humor me will you, my memory isn't what it used to be.

[SSpdDmon]

I got to thinking the same thing at one point. There's a guy not too far from me who has a flowbench he could stick my MAF on and give me a calibration curve since my SLP MAF/SLP Lid combo isn't stock. I almost thought about doing that...just don't want to spend the money on it.

Aside from that, I think it'd be a little hard to calibrate the VE while the MAF is active. From what I've read and what I've observed in practice, it's almost like there's a swing factor that we can't see. In other words, if the VE calculation results become more distant from the MAF calculation, it's almost like there's some factor that will try and lean towards the side it thinks is more right. I don't know if that makes sense...but, I know I've tried changing the VE while the MAF was active and saw some weird results (almost like they were the opposite of what I was trying to accomplish).

I was hoping the guys on here who wrote our software would jump into this discussion to possibly shed some more light on the subject...

[johnsZ06]

I got to thinking the same thing at one point. There's a guy not too far from me who has a flowbench he could stick my MAF on and give me a calibration curve since my SLP MAF/SLP Lid combo isn't stock. I almost thought about doing that...just don't want to spend the money on it.

Aside from that, I think it'd be a little hard to calibrate the VE while the MAF is active. From what I've read and what I've observed in practice, it's almost like there's a swing factor that we can't see. In other words, if the VE calculation results become more distant from the MAF calculation, it's almost like there's some factor that will try and lean towards the side it thinks is more right. I don't know if that makes sense...but, I know I've tried changing the VE while the MAF was active and saw some weird results (almost like they were the opposite of what I was trying to accomplish).

I was hoping the guys on here who wrote our software would jump into this discussion to possibly shed some more light on the subject...

I noticed the same thing when trying to tune VE with the MAF connected. It seemed as if I was going the wrong way which I thought was strange, but then I just blammed it on not knowing what I was doing.

I might play around with this idea some more this weekend just to see what kind of results I get. After all, that is one reason I bought the software - so I can tinker!


About having some of the software guys chiming in, I think they already did in the Flash Scan software where they make the following statement...

This table should only be modified to suit a specific MAF sensor's characteristics.
Though it can be, this should not be used to adjust overall fuelling.

[Doc]

That guy in the LS1tech thread is a tool. I don't have to get into an esoteric physics debate to know what works for me. I use the RR, an LC-1 and the track/dyno know that I get the proven results.

That guy essentially has said "You suck and your method sucks," without offering any real proven information because he "Doesn't want to give away all that hard earned knowledge." Whatever.

Look at me, I've got a 5gas analyzer and I Know how the software was engineered. You rubes with your cheap widebands and VE tuning are all fakers.

So I guess we should all line up and bow down to LS1Bi-curious?

[johnsZ06]

That guy in the LS1tech thread is a tool. I don't have to get into an esoteric physics debate to know what works for me. I use the RR, an LC-1 and the track/dyno know that I get the proven results.

That guy essentially has said "You suck and your method sucks," without offering any real proven information because he "Doesn't want to give away all that hard earned knowledge." Whatever.

Look at me, I've got a 5gas analyzer and I Know how the software was engineered. You rubes with your cheap widebands and VE tuning are all fakers.

So I guess we should all line up and bow down to LS1Bi-curious?

hehe...yeah, tool is putting it nicely. He was pulling crap out of his arse. I will say this, he did get me to think about the current way I'm tuning.

[Redline Motorsports]

I kind of agree that if GM has the MAF transfer function setup to report that a given hrtz equals a given lbs/minute then changing that scale would provide a false value. From a tuning standpoint whatever gets the fuel dialed in............works. If the VE table (or what I refer to as the base fuel table) is properly calibrated, with MAF disconnected, then re-enabling the MAF and scaling to match the commanded numbers would most certainly disturb the MAFS reporting accuracy...............but the cars tuned.

What does this really screw up?? How often do you tune with lbs/minute values??

Good topic!

Howard

[johnsZ06]

It seems to me that fudging with the MAF is equivelant to fudging with the IFR table in order to correct for fueling, which IMO is not the right way to do it although you can obtain the same results.

What I plan to do is build a map that logs VE as a percentage, which is calculated of course, against the intake manifold pressure (MAP) and log a histogram while leaving my MAF plugged in and see how that compares to my current VE table.

Theoretically speaking, I should be able to plug those values into the current VE table and have my Ltrims close to zero.


BTW, I compared my current tune MAF table and noticed the values were much higher than the MAF used on the LS2 which I'm sure flows more air. I know this can't be right.

[redhardsupra]

It seems to me that fudging with the MAF is equivelant to fudging with the IFR table in order to correct for fueling, which IMO is not the right way to do it although you can obtain the same results.

YES! you got it!

ultimately the point of the PCM is to calculate the pulse width, whether it uses the MAF lookups or SD calcs.

IPW=airflow*RPM*IFR*AFRwb (MAF)
or
IPW=VE*MAP*CYLVOL/(IPW*AFRwb*R*TEMP) (VE based SD)
or
IPW=GMVE*MAP/(IPW*AFRwb*TEMP) (GMVE based SD)

so you can get the same IPW number by dicking with MAF, IFR, AFRwb, TEMP, MAP, VE or GMVE.

the HUGE problem is that while you can make it work for singular numbers, it's very difficult to get it to be right all the time, given the tables we got. IFR is not linear. AFRwb is twitchy at best, TEMP is highly non-linear and modeled based on a bias table which should change if we mod things. then you take all these non-linear components and combine them into a IPW calculation. do you really think the result of that is gonna be anywhere near as simple as he claims?

these days, VE and GMVE have become the 2d replacement fudge table for the former 1d IFR fudge table

this is a much more complicated model than people think. this dude just wants to mess with OLFA and VE, which effectively is accounting for ECT, MAP and RPM. still not accounting for IAT, IFR, and air density in general.

no math, no soup for him, whoever said that in that thread oughtta get a beer.

[johnsZ06]

YES! you got it!

I got something? Oh Hell, there goes the neighborhood!

[Doc]

I'll have a Guiness, Brilliant!

Seriously, this sad, tired, argument LS1curious presents had me second guessing my navel lint a few years ago. Then March 12, 2006 I got my Road Runner and that thing opened my eyes and flushed all of his types of agruments down the toilet. For those without a RR I don't see how his "way" would be any more successful than the accetped AutoVE/MAF tuning method expoused on this board and as exhibited by Jeff's (SSpdmon) failed experiment trying to employ his methods.

If you can get the vehicle to produce the desired A/F on a lowly WB throughout the various states, ECT, IAT, load values and be "so smooth your momma could drive it," then I don't care how you do it.

It just so happens that there are quite a few folks on this board using this product that have been able to reproduce the same desired results time and time again. All I see on Tech for the most part are confused HPT users with very inconsistent results.

Note the OP in that thread was a HPT user trying to find out how to tune his MAF.