APeteSS

Just as the subject reads, do the MAF tables (LS1_Edit) need modification for larger MAF ends (basically porting and descreening)? Or, are these tables for MAFs with non-stock calibration?

Thanks

slow

iTrader: (7)

not understanding your question.

when you hack your maf sensor, you need to adjuist those tables... there is just 1 problem with it, you don't know the correct calibration to enter, as the maf ends alter the maf output, and nobody has the data provided to go along with that mod

Ryan

APeteSS

yeah, that's what I was thinking. Should I leave the table as it is, or adjust it by something like 5%? I have no current power or drivability issues but am interested in a more customized tune.

Another_User

I have heard of good results using the MAF table from the 2002+ Z06 Corvette (screenless MAF) for descreened MAFs....don't know what else you could do to it, but it would be a good place to look and start comparing.

Billiumss

iTrader: (11)

I have actually used my car as a test car to find out if removing the screen and going to ported MAF ends changes things.

It sure does!!! I probably did about 200-300 miles worth of testing and found out that a MAF with the screen removed and/or ported MAF ends with no screen throws your Ltrims off by about 5%.

From the research that I have done, dynoing cars, and asking a few pros, the best bet is to leave your Stock MAF; Stock! A tad easier to tune and is not a restriction unless your over 450-500HP.

Ragtop 99

iTrader: (7)

If you know your change in LTRIMS, you can increase the MAF enough to bring them back in line. Better to do that than to let the car run lean. The car's load calculations are likely to be off since the MAF is under-reporting the air going in which can be a factor in determining the correct line pressure for an A4.

WS6snake-eater

If the MAF is under-reporting the flow, then should you increase or decrease the values in the MAF table? My car had a descreened MAF when I purchased it (used). Now that I have a lot more extensive mods, I believe that it may be causing some of my surging and LTFT issues. So I figured I could scale the table by a few percent and maybe get closer in line. The only question is should I scale it up or down???

WS6snake-eater

I fall into this catagory "450 - 500HP"...if it is throwing the LT's off by 5% then should the table be scaled 5%?

jimmyblue

iTrader: (11)

I would say, look to the higher-RPM, higher-
MAP cells for LTFT guidance. Like 10 & 11 if
you are set up to touch those. Forget the
0-3, 4, 8 cells as the MAF is really not too
involved there. Multiply the whole table by
1+(LTFT/100) and you should end up about
neutral (maybe add a little for luck and
environmentals).

You may have to shave on it some more if the
MAF ends' effect is not a constant scaling
across the board, but this is a start.

This method lumps all nonidealities onto the
MAF table, whether or not the MAF was the
only thing responsible. The more mods you
have tangled up, the harder it is to get all of
the various model tables properly accounting
for their individual responsibilities. That's why
having a spare, stock MAF can be handy -
one less thing to make assumptions about.

Billiumss

iTrader: (11)

If you took out the screen and/or have ported MAF ends, highlight the whole MAF table and multiple it by 105% if you are using LS1 Edit.

WS6snake-eater

That's the answer I was looking for...sorry Jimmy you kind of lost me on your explaination...I don't have my HPtuners software right here in front of me at work. So I will go home and look at it, then re-read your post. But I am going to start with Billiumss suggestion with the 105%, and go from there.

383838

iTrader: (1)

From my experience it's not a linear 105%, is actually a non-linear curve. The right way to do it is log your MAF frequency vs. LTFT's over a period of about 100 miles, the take the average LTFT change for a given frequency and begin there. That's the right way to do it but it's a pain. The problem is the ported ends change the way the air enters the MAF so at certain flow rates it will be similar to stock and at others it will be very different. This is why people with ported MAF's always have larger LTFT swings than those with stock MAF's. An easy trick to help even things out is to make sure the rails in your MAF sensor are running vertically and not horizontally as the air at part throttle tends to want to hang to the top of the intake.

Billiumss

iTrader: (11)

I have TR MAF ends with my stock electronics and my Ltrims vary from -2 - -10 all the time and lock at 0 everytime I go WOT with my 5% change that I made. I have put hundreds of miles on my car and they are always the same. I have logged 2 completely stock cars before and their Ltrims were always like mine.

I have heard of it being non-linear though, but once you change cams, heads, exhaust, some things go out the window.

moehorsepower

iTrader: (3)

You are exactly right, It is much better just to leave the MAF STOCK. The only thing I would reccommend is de-screening it and thats it. Though we had a LS1 on the Dyno and did a before and after A/F with and without the screen and it leaned it out a full Point!!!