I've heard different stories.One is the screens are there to straiten out the airflow past the wire sensor to get a more accurate flow reading.The other is to keep debris away from wires inside.I'd leave them in.The mafs an expensive piece.
Last edited by steven mack; 03-26-2009 at 09:19 PM.
Reason: add info
I've heard different stories.One is the screens are there to straiten out the airflow past the wire sensor to get a more accurate flow reading.The other is to keep debris away from wires inside.I'd leave them in.The mafs an expensive piece.
I believe this is the correct technical answer. The screens are used to have an uniform air flow past the resistors (wires). The computer (ECM/PCM) is expecting certain data based on the specifications of the MAF in computing A/F mixture.
I won't disagree about increased air flow. You have to decide if the gain is worth it to you. All I have read about mods falling into two categories of what works (worth it) and what doesn’t, that mod fell into the does not part of the list.
I kind of looked at these as feel good mods no real seat of pants gains. But the by-pass cleans up the front area.
There is no such thing as a free lunch. You can do all of the "free" mods found on the forum and in the end only have a few hours of your life missing.
You might throw the cut air box lid into this category as well.
The only what I would call free mods if you can do your own work that is, would be some porting of your intake system plenum, runners, base manifold. HP & torque gains are not great but it dose seem to move the gains into the mid range of your RPM band. With out head & exhaust work not sure that is worth it either. But if it makes you feel good do it.
Recently, I was playing with a Flow Illustrator and decided to do a rough model of a MAF with & without screens.
Interesting to see, and probably what you would expect
Recently, I was playing with a Flow Illustrator and decided to do a rough model of a MAF with & without screens.
Interesting to see, and probably what you would expect
If the MAF didn't need the screens, would GM spend the money putting them on???
Seeing as I believe it was a Boch design I doubt GM did much engineering on that part.
But I do like the explanation of "Because the other cars it's mounted on aren't a straight shot, there's an elbow, it's used to straighten the flow."
I think also they did it to keep things out of the MAF and destroying the wires.
The wire is pretty strong, and the air filter stops debris. Without an air filter something large enough to damage could get in there but otherwise, no way.
The MAF flows something like 200 CFM more without the screens. They've been out of my car for years, and the TB coolant bypassed as well.
The wire is pretty strong, and the air filter stops debris. Without an air filter something large enough to damage could get in there but otherwise, no way.
The MAF flows something like 200 CFM more without the screens. They've been out of my car for years, and the TB coolant bypassed as well.
I have mine out also along with the by pass & cut lid, but I do think GM has to build cars for idiots. We all know the guys who just say why do I need a air box or cleaner or one that has been in there for 100k miles.
I have a little spread sheet I use to calculate and size exhaust systems.
But it's good for looking at the intake also.
The MAF sensor and code will only read up to 254 grams/sec.
That works out to about 451 CFM and 313 FWHP.
After that the MAF is out of the picture, and you have to tune with the WOT tables.
In the old TPIS "Insider Hints" book, they tested the stock MAF @ 529 CFM, Screens Out @ 711 CFM, and Fully Ported @ 750 CFM.
So I get roughly,
Fully stock 529 CFM would support 367 FWHP
Screen Removed 711 CFM would support 494 FWHP
Fully Ported & Screens Removed would support 520 FWHP
So your FWHP in relation to those numbers, would determine if removing the screens would help or be a waste of time.
I have both a completely stock (I use for emission testing) and a fully ported & no screens MAF.
I have an old school Paxton SC, and around 450 FWHP.
The fully modified MAF runs a little over 1-1/2 mph faster, in the quarter mile, than the stock one.
But even with heavily modified MAF tables, my engine does hunt at idle, and part throttle response isn't as good
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MAF Screen
I believe this is the correct technical answer. The screens are used to have an uniform air flow past the resistors (wires). The computer (ECM/PCM) is expecting certain data based on the specifications of the MAF in computing A/F mixture. 
