MAF Grams/Sec Limit 2455.25@15000Hz Is scaling necessary for a MAF'less tune

[MN C5]

If this upper limit is correct what reason would there be not to run a MAF? Perhaps I'd be better off with a 100mm LPE MAF than going MAF less. Table B1099 shows a max Grams/Sec of 3000 for my OS.

Some are now going to a MAF only tune and disabling the VE table WTF:doh2: Have I've been doing in wrong all this time or :gossip: not. What are the benefits of a MAF only tune in both a Boosted and N/A situation. If the upper Grams/Sec limit is truly 3000 why would you need to scale the tables to work around it or is that for older gen ecm's?

Aren't most Ford tunes MAF only? With no VE even their boosted cars?

[mr.prick]

Ford MAFs work differently than GM.
I have heard of people using MAF with FI,
relying on PE once it maxes.

The problem with the MAF is 15000Hz is not enough.
I hit 9000Hz N/A @ mile high altitude.
N/A is like what, 1psi :nixweiss:

[dc_justin]

Ford MAFs work differently than GM.
I have heard of people using MAF with FI,
relying on PE once it maxes.

The problem with the MAF is 15000Hz is not enough.
I hit 9000Hz N/A @ mile high altitude.
N/A is like what, 1psi :nixweiss:

It becomes exponentially more difficult to hit higher hz. A relatively stock 5.3L can hit 10,000hz, but takes 10psi to hit 12,000hz on that same engine. 15000hz should be more than twice the air flow of 12,000hz when scaled properly.

[mr.prick]

So the table itself is not the limit but the values in it?

[dc_justin]

Realistically, you'd have to be making pretty big power for either to be a limit. I'd wager that 15,000 would be the equivalent of 1100-1300hp worth of airflow...

[mr.prick]

I thought the table/value limits were why everyone uses SD for FI.

[dc_justin]

On Gen-III and early Gen-IVs. As pointed out here, that is not the case on the later Gen-IVs.

[mr.prick]

:doh2:
Thanks. :good:

[gmh308]

As DC Justin points out, the 512g/s limit was with earlier OS's.

For MY08 GM switched most OS's from the lo/hi MAF scales with 512g/s limits to the higher 3kg/s limit. Though have seen this limit listed as 4kg/s. Plenty of scope-8 times flow almost. Though would need injectors to do over 30 g/s to keep up.

Though the LS7 Corvette still uses the 512g/s limit even for '09 at 500HP. So would guess 3kg/s is good for 3000HP :doh2:

[ringram]

07/08 holdens also have the same 512g/sec limit.

Other reasons to run mafless are to remove the albiet limited restriction they pose as well as the fact that low throttle transients are better detected and responded to in SD mode. Also larger cams and reversion can mess with the maf as I understand it will measure the airmass twice as it goes both ways over the element. Plus in some instances you can get a shorter colder airflow into the TB if you dont have to try and package the MAF in there as well.

[MN C5]

The problem I'm having right now is that my check engine light flashes under part throttle boost and pulls timing and but leaves no traceable codes (though I suspect its the MAF somehow). And I'm currently at a loss as to which table is being used to pull timing.

Plus, with either of the TVS superchargers I've run I'm not able to using VVT without it totally messing up the shift points. As the KPA at part throttle rises under boost it shifts up through the gears with a mind of its own unless VVT values are set to 0. WTF

For now I'd view the MAF only tune as a band aid for not having your VE table dialed in if not limited to 512gs.

So who makes the best 100mm MAF:help2: