Blackbird

I max out my MAF by 4900rpm now. I just came across a post where Harlan suggests using a MAFT and for example set it to -10% then go into edit and scale the MAF table 110%

Anybody out there doing this?

Worth finding a used MAFT or just add fuel via the PE vs RPM table?

I kinda like the idea of the computer being able to do it's job but on the other hand I don't want to waste $100

kp

iTrader: (34)

If you do that it will make it the same I would think - taking 10% off the MAFT and adding 10% to the MAF table would sorta even out..

You would adjust the base, then adjust the IFR table to get your trims back in line if you wanted to use the MAFT with edit. Your reported airflow can be adjusted easily like that, but you will have to scale your PE table OR use the WOT setting on the MAFT to adjust the WOT fueling. I modified the MAF so it reads lower and extended the MAF table in edit so it reads to 67lb/min. It works fine for me, I use the MAFT just for wide open setting, my WOT a/f is very consistant from 45 to 90 degress out plus I am just a couple a clicks away from changing my a/f according to the in car wideband. I have the PE table adjusted so the car is ~11:1 a/f and each click of the WOT setting on the MAFT is .5 a/f +/- change. I still get good mileage, driveslike stock and my ltrims vary little from cell to cell and I dont have to mess with LS1edit at the track. Works for me anyhow..

You can pick up a used MAFT for 50.00 so its worth playing with, dont get hung up on the version numbers they all do the same thing except the newest 5.2 version has the switch for the 85mm truck MAFs.

I ran my old car with nothing but a MAFT and 38lb injectors and basically that is what I did. The MAF read 42.5 lbs at WOT since I had the base cranked down so much to use the bigger injectors, there was no LS1edit available at the time. Only problem I had doing it that way was the car would run rich on a dead cold start for a few seconds but other then that the car drove just as well as this one...

Blackbird

how did you do this?

Thanks!

kp

iTrader: (34)

A resistor, but you can do the same thing with a MAFT

QuickSilver2002

I’ve thought about trying a MAFT myself. I have a 2002 MAF and it is basically maxed out at 428g/sec all the way down the track now. I’m pushing about 670RWHP.

I have noticed that my EFI logs show the frequency still going up (but it is obviously out of the PCMs range). I’ve had to do all my tuning with PE vs RPM and I would love to have something that was a bit more adaptive.

So how does the WOT setting work on a MAFT. At what frequency does it start to adjust the output frequency.

kp

iTrader: (34)

You can change the MAF numbers in LS1edit to read all the way to 67lb/min on 99+ cars instead of 58. Pulling the screen drops the MAF numbers, ported MAF ends drops it even more. I used the resistor method because I didnt have a MAFT on the car at the time, some people get **** about commanded a/f and all that coming out perfect but I just change whatever numbers I feel necessary to make the car fuel properly at WOT, keep the MAF from maxing out and keep the LTFTs a little negative. If most people looked at my LS1edit file they would probably be amazed the car even runs

I dont know what frequency or how the MAFT puts itself in WOT mode, I would assume anything past a certain frquency triggers it. One of the guys that designed the thing was working with me to try to get the super rich cold starts fixed and he explained it but I just dont remember, was a few years ago.

QuickSilver2002

You can change what frequency = what g/sec within ls1 edit but you cannot change the frequency range that the pcm will accept (unless I'm missing something here). So in my case(2002 c5 coupe - plastic MAF), I would have to use a maft to adjust the frequency output of the MAF to get it into the range the PCM will read (750-1200hz)

You will notice in the image of my efi log below that my maf reading is flat above 1200HZ (which is bascally all gears but first for me now).

the blue line is raw freqency and the yellow line is g/sec

White_Hawk

iTrader: (3)

No matter what you do, the highest you can set it is 511.99 g/sec. I think the MAFT will only help you if you are getting errors for MAF frequency out of range. I guess until you hit 511.99 though, there might be some benefit to it.

-Geoff

kp

iTrader: (34)

The MAF table stops at 439g/s @ 11250 Hz, you can scale the numbers up until 511 @ 1200 Hz on 99+ PCMs and the metal MAF will read that high. True you cannot read over 1200hz but I used a resistor to drop the reported output of the MAF after experimenting with a few different values. Adjusting the base on the MAFT would do the same thing as the resistor on the MAF, either way you will have to change the IFR to get your LTFTs back in line - less reported air = less fuel from the injectors. The PE tables will need some adjusting as well. As you can see on this pic the MAF is reporting over 439g/s.

Its really not that bad using the PE tables only except weather changes hurt, using a MAFT along with an in car wideband and the MAF working all the way to redline makes quick a/f changes at the track a breeze and weather changes affect WOT a/f very little. I'm sure there are better ways of doing it but this works for me Its also working pretty well on a TT C5 I am playing with..

QuickSilver2002

Yep, I have been avoiding playing with an MAFT(or a 99 metal MAF) becase I'm pretty sure I will be hitting 512 g/sec way before redline anyway. Not sure if it is even worth fooling around with.

My car runs great the way it is now, I just have to keep it pretty pig rich at WOT and I'm always having to keep an eye on it (which does get old).

Wow KP, it looks like you are running some pretty stout timing there. 25* ehh. I thought I was being pretty aggresive with 19-20.

kp

iTrader: (34)

I can run 27 if I want at 7.5-8psi when its cool outside but I knock a few degrees out to be safe and it really doesnt change the hp on the dyno. Going from 11:1 to 12:1 a/f will pick up ~20rwhp though

The idea of using the MAFT Blackbird was referring to (I think) is to bring down the base on it so the overall reading of the MAF is lower and it car read the whole range. If the metal MAF stops at 1200hz then the MAFT wont work but the resistor mod will. I'll find out when I try the dry shot of n2o If I didnt have the resistor in the MAF and had the screen still in it it would max out at 5800rpm.

Blackbird

right what I am trying to do is see if Harlan is right that I can basically make the maf report less air yet have the computer still make the right decisions. Looks like I am getting a MAFT for free so I will give it a shot.

kp

iTrader: (34)

If you report less air the computer will put in less fuel, thats why you can put 38lb injectors in and use a MAFT alone to make it work. If you just crank back the WOT on the MAFT you will need to up your PE tables.

You will see what happens when you play with it, everything will still 'work' fine, it will take some playing with but it will work up to certain point - try it and see, its free