MAF De-screening ?

F Body · December 22, 2009, 04:12:22 PM

Now as most of you will know modern EFi engines have a MAF ( mass air flow ) sensor before the intake manifold.

These are manufactured with a mesh screen in front of the very delicate wires which actually do the measuring, many people and forums recommend removing the mesh screen.

http://www.ls1tech.com/forums/new-ls1-owners-newbie-tech/1101786-descreening-maf.html\" target=\"_blank\" rel=\"nofollow\">http://www.ls1tech.com/forums/new-ls1-owners-newbie-tech/1101786-descreening-maf.html

The general theory is that it increases the air flow and thus aids performance

My own belief is that the manufacturer who probably invested millions in developing the MAF knows best which is why they put it there in the first place

Anyone de-screened a MAF ???

F Body · December 22, 2009, 04:16:47 PM

Found a video :

http://videos.streetfire.net/video/LS1-Upgrade-Testing_643805.htm\" target=\"_blank\" rel=\"nofollow\">http://videos.streetfire.net/video/LS1-Upgrade-Testing_643805.htm

HardRockCamaro · December 22, 2009, 04:31:11 PM

I descreened the IROC MAF, amongst other things...

Big Mouse · December 22, 2009, 04:54:49 PM

Yep, when the car was original I ripped the screeen off - made absolutely no discernable difference but didn't do anything bad either.

Titsy · December 22, 2009, 05:12:01 PM

Quoting: F Body

Anyone de-screened a MAF

That doesn't sound very 'stock'....

art b · December 22, 2009, 06:46:49 PM

n the skyline forums, they think it disturbs the airflow if it removed,it is there to spread the flow evenly....

EDGE · December 22, 2009, 07:13:55 PM

It's usually there to form a laminat airflow over the maf. In some turbo cars they are installing an extra screen to smooth the turbulent air before it hits the sensor

to be honest I can't see descreening helping at all. I'd leave it alone.

FUBAR · December 22, 2009, 08:48:03 PM

Quoting: EDGE

to be honest I can't see descreening helping at all. I'd leave it alone.

Its a fine mesh... I can't see it having any beneficial effect greater that the protection it offers to the very delicate sensors, all you are going to gain is a misicule increase in intake flow that could be more than compensated for by other intake components such as large bore TB's & manifolds / runners, albeit at a greater price.

Fieldy · December 23, 2009, 03:11:05 AM

Quoting: EDGE

to be honest I can't see descreening helping at all. I'd leave it alone.

I would leave it alone personally.....

F Body · December 23, 2009, 04:52:40 AM

Interesting replies

There is one very good reason that i asked this question

I've started to do the Camaro's yearly service and started with the easiest thing which was the air filter

Looks like new on the manifold side :

Doesn't look bad on the outer side :

But wait

look at the MAF

It's a Pucker GM air filter 12 months old, I've double checked the fit and all the seals and they are all fine

The only other route of entry is via the balance pipe tube ( the rubber pipe in the middle of the next photo ). This draws air from behind the air dam to reduce induction noise

I know that the car does spend a large proportion of it's time driving across show fields, but never expected that

So two points then :

1 : If you De-screen your MAF all that crap is going to hit the sensor wires and be sucked into your engine.

2 : Do I block off the end of the balance pipe to keep the crap out ???

art b · December 23, 2009, 05:30:11 AM

at least ya dont need an new air filter....

or oil
or plugs
or a service....

cuban pete · December 23, 2009, 06:07:19 AM

did it on my 85 tpi vette and re chipped it . did not make a darn bit of difference to be honest .

put it this way , not going to bother to do it to my z28 turdy

Titsy · December 23, 2009, 10:31:20 AM

I'd leave the MAF as is because if it gets fooked then they are blody expensive to replace. But I'd block the balance pipe for two reasons: it's letting shit be sucked up; and the induction noise will be more throaty as a result...

Jamieg285 · December 23, 2009, 10:40:32 AM

Quoting: Titsy

I'd leave the MAF as is because...

plus it's probably easier to reverse if you change your mind.

Titsy · December 23, 2009, 11:15:12 AM

Quoting: F Body

the rubber pipe in the middle of the next photo

I'm sure that shouldn't just be hanging down sucking up crap.... You sure it doesn't connect somewhere...

Big Mouse · December 23, 2009, 12:48:49 PM

IIRC the balance tube is supposed to draw air from the baffles at the back of the airbox to balance pressure behind the filter (hence the name) so theoretically nothing should be able to travel up it when the vehicle is in motion as it would be against the airflow. I can't remember where it terminates now but I'm sure it doesn't just dangle.

If GM had given any thought at all to the route taken by the air once its passed through the filter, they wouldn't have needed to put a screen on the MAF to 'even' out the airflow - passing through the the baffles and ribbed rubber connector pipe mess the airflow up good so why bother to try and fix it again? If it was a problem they would have cleaned the route in front of it - like cutting out the baffles which is basically what all the aftermarket air lids do. I fitted a smooth bellows to mine at one point which looked better than the GM left-over-from-British-Rail hose.

The sensor on the MAF is very fragile, the slightest damage and it gives up; the screen just protects it.

Personally I would have dumped the GM filter for a K&N unit. Last so much longer (so cheaper in the long run), does a much better job in keeping the air clean and also adds a positive bit of oomph to the performance.

F Body · December 23, 2009, 01:05:10 PM

Quoting: Big Mouse

Personally I would have dumped the GM filter for a K&N unit.

Quoting: Mr Originality

You have got to be kidding right ?

I even put GM Brake Fluid in the old Gal

philoldsmobile · December 23, 2009, 01:24:39 PM

its a sign of the times, GM were cutting corners big time when they built 4th gens, thirdgen IROCS and trans-ams had K&N filters as factory fitment.

something is definitely wrong in the intake plumbing, as there is no way some of those items (especially the hairy fluffy seed things) could pass through a paper filter so there must be an air entry point past the air filter. this is of course not right..

its not unusual for manufacturers to do things wrong on the line, so just because the balance pipe is in a certain position it doesn't guarantee its right.

art b · December 23, 2009, 01:57:09 PM

put a filter on the balance pipe.....

HardRockCamaro · December 23, 2009, 02:35:03 PM

I descreened the MAF, fitted the foam filters, cut the bottom out of the airbox, filed down any protrusions in the airbox and intake pipe, filed down the "walls" at the entrance to the tpi plenum, matched the gaskets to the intake runners and plenum and chipped it.

I can't say if it helped or not, but when matey from Autopontiac drove it he said it felt much more sprightly than when he had driven it previously (he did the servicing for the previous owner), and no, I hadn't told him what I had done...

I don't think these little things on their own amount to much, combined you might release a few bhp, but their benefit is greatly increased on a modded engine.

Titsy · December 23, 2009, 07:38:49 PM

Quoting: philoldsmobile

something is definitely wrong in the intake plumbing, as there is no way some of those items (especially the hairy fluffy seed things) could pass through a paper filter so there must be an air entry point past the air filter. this is of course not right..

Titsy · December 30, 2009, 02:17:42 AM

What was the deal here? Did you find where the hose hooks up?

F Body · December 30, 2009, 05:05:21 AM

Quoting: Titsy

Did you find where the hose hooks up?

Yep, I'll post up a picture when I get home from work

F Body · December 30, 2009, 01:30:55 PM

Quoting: F Body

Quoting: Titsy
Did you find where the hose hooks up?

Yep, I'll post up a picture when I get home from work

As we already know the hose runs from the right side of the filter box :

It then drops down under the fuse/relay box:

Then down below the headlight into the bottom of the near side wing ( the pipe marked AA) :

It goes to the Secondary Air Pump which according to the GM Service Manual lowers tail pipe emissions on start up, apart from the next two pictures and a wiring diagram there is bugger all information about it

Checked and all the connections are OK, in the absense of any further information I assume that it sucks filtered air from the air box and pumps it to the EGR valve ( can't see why the other outlet pipe goes )

Therefore it should only suck clean filtered air and not feed any air back into the box, I then checked all the airbox seals again and they all look OK

Since it runs fine I'm going to leave it and look again at the MAF screen later in the year, unless anyone has any better ideas