PSA: Don't descreen your MAF!
 

At least with a Volant intake that is...

So I just finished putting some parts into my '00 Trans Am, a Volant intake and an SLP Loudmouth I Yback. I also descreened the MAF from the advice in this article. Everything was going smoothly, until she started bogging under anything more than half throttle...

I was getting codes for all the O2 sensors and the P1133 as well. Couldn't figure out what was going on, so I researched the MAF design a little more.

Turns out that this MAF expects the air to be in a relatively uniform straight line. The turbulence created by the Volant's two filters going into a Ypipe was enough that, without the straightening action of the screen, it was screwing up the readings and leaning out the AFR. A new MAF sensor, with the screen, fixed everything.

This is why I use an LS3/7 100mm MAF :)

Yea that's was one of those bs free mods that supposedly did something when he LS first came out...then guys starting running into problems.

The screen is a air flow straightener to keep turbulence down across the sensor. I've done it and not had any problems but after my vararam on my C5 Z06 it has some minor surging at times with the stock cam. Thats why everything I've got is speed density. We all live and learn.

I ran both the ls1 maf and 85mm maf descreened with the volant. No issues

No way. I got at least 10 h.p. from the throttle body bypass. :gtfo:

De-screening the MAF was done on every one of my cars, 6 F-bodies. The worst symptom I had was on my B4C, where it would throw a code after driving a lot in stop and go city driving or lots of low speed. That code would automatically clear after a couple drives at 30+MPH. Granted, I wasn't monitoring AFR, but it seemed to do alright considering the car had 175k miles when I voluntarily replaced the motor to do more than just bolt-ons.

The straightener is virtually ineffective from the factory because it's so shallow and the cells are so tiny. A Saxon PC screen is a nice way to ensure accurate measurement while maintaining good airflow. That, or a larger MAF, but I'd still recommend replacing the screen.

So thanks for the PSA, but I respectfully disagree :secret2:

I tried a de-screened MAF on my car when it was stock. It then had an annoying bog at certain engine speeds. Went back to a stock MAF with the screen and the problem went away.

It does seem that some cars run perfectly without the screen and others develop issues.

I've descreened the MAFs on both my cars and replaced them with those honeycomb style airflow straighteners. Can't say I felt a lot, but theoretically they are less restrictive and do a better job of straightening the airflow.

Descreening a MAF just seems scary to me, in terms of accidental crap getting into the engine.

I know it isn't designed to be a filter, but I've seen a few little leaf scraps in there when I cleaned mine.

There is a noticeable difference in low end responsiveness and MAF scale clarity in those lower hz ranges with a screen vs none. Now you probably could gain some on the top end because of how tiny the holes are on the OEM screens, but some form of screen should be used at the very least on a cammed car.

Where do you get your airflow straighteners? I accidentally broke a few cells on mine and removed it because of that when it was out.

Also are the cells larger, causing less resriction?

Here ya go. http://www.saxonpc.com/

They're much larger and DO make a difference.

Which ratio do I get? 5:1?

That's what I went with

Cool, seems easy enough. Thanks for the info.