87Formula356

Iv'e read alot of threads about how it's ok or not ok to remove your MAF screen. Many people say that they have removed the screens and they have had no problems. Others say that it's a bad idea because the screen is to block somthing other than particles. I have a 350 with about 350 horsepower I removed my MAF screens about 2 weeks ago, and i slowly noticed my car's reliablity deteriorating, i wasn't sure why. One night it was cold and the humidity was right, and i stomped the gas only to rev up a bit and suddenly stall out. the car ran like crap and i got home, checked the code and it was 33!! MAF sensor, (too much airflow). I quickly ran to autozone and picked up a new one for 160 bucks. And the car ran better than it has for weeks. i share this story to let anyone who is curiouse know that there IS a risk when you remove the screen. and there IS a chance u can be replacing a rather expensive part of your car, if you decide to get somthing of higher quality than autozone you may end up paying alot. So beware.

qube

I removed mine, didn't notice any difference to the car.

Matthew

TheMysticWizard

iTrader: (1)

I removed my screens, car has never been the same since. I think it was a bad idea. My gas mileage went down, it just doesn't seem to have the same amount of power..

It's another one of those things, you can't really tell if it's different or if your imagining it or not.

Needless to say I want another maf, to see if it's really a difference.

qube

A bit more expensive for me over in the UK as I was quoted £600 for a new one.

87 BlUEROC

Yeah, this is one of the old "FREE" mods, I did it to my factory MAF, also built a cold air intake system and have K&Ns in the path, and I still busted a wire in my MAF. I ended up going with the WELLS unit, bought from some company in Buffalo, NY cost a little more than the ones at Autozone, but has the chip inside. No more wires and works great. But it does make my SES light pop up every once in a while. I think there may be a fix for that, but I got so many mods going now, couldn't tell you if that was the problem or not.

And if they cost that much across the pond, I would buy one here and have it shipped!

Good Luck!!

MikeInAZ

Removing the MAF screen increases airflow.

So does removing your air cleaner and sawing off your exhaust at the manifold but it's a lot easier to see why these are left intact.

2.73's Suck

yea F that unless your making like 600 hp the screens probably wont make that much of a difference, except for ruining your MAF. port the plenum first. 134k and my MAF still works, no chance of me taking out the screen.

Morley

Removed my MAF screens 16 years ago, still running the same MAF and it works fine.

pecha

removed my screens some time ago, the wire is fine, no codes thrown, nothing
HOWEVER, the car got undriveable! you could not press the pedal and go, it was stalling.
Having no code thrown at me I didn't know what was going on BUT I borrowed another MAF from a friend (Z_Power) and everything went back to normal so it had to be maf problem
I'm too running wells maf and seriously, if you wanna sth more reliable and you have to get maf, get wells - chip instead of a wire should be more durable

Guest

Screens have been gone for about 10 years now.

2.73's Suck

sounds like luck, I have terrible luck so theyre staying in

formularpm

Screens out for 5 years, no problems.

88TPI406GTA

This obviously shows that you do NOT burn your own chips...because most of the time the Code 33 appears it is due to the stupid max gm/sec under 2000 rpm parameter that GM put into the stock chip.

Also, your MAF may have already been on the way out...It is not uncommon for the brittle plastic to crack around the connector...make sure you check the plug too.

vexter

iTrader: (3)

^^^

TransAmman87

I have had my screens out for the past year and a half and have not had one bit of problems.

qube

Anyone notice an improvement?

Matthew

DANIELEK

Screens and fins removed 3 years ago, car runs beautiful, quick throttle response, etc..

305PhoenixAm

I just removed the one on the end of the MAF a while ago, kept the one on the incoming side just in case something comes to threaten the wire. Haven't had much of a problem with it ever. No increases either. Oh well.

MikeInAZ

Besides being bug catchers they serve a much more useful purpose. Their secondary purpose is to act as a safety net from backfires on the rear side to protection from debris or accidental handling on the front.

Their primary purpose is to provide a stabilized chamber in which to get an accurate reference point measurement from which by increasing or decreasing the airflow into this chamber the computer and engine functions will be adjusted accordingly.

Your car may work OK without them. May work fine without them but it is impossible to work correctly without them.

Unless you have a heavily modified engine removing the screens is not even a performance mod. Even then a heavily modified engine probably should be running speed density with a custom chip.

I have never seen one case of a validated verified 1/100th of a HP gain by hacking out the screens. I have seen several guys turn white as they say bye bye to a hundred bucks or two.

For good reason. A stock MAF will outflow a stock 48mm throttle body. It will outflow a 52mm throttle body. It will outflow a stock intake. So until you have dealt with these more restrictive issues it's a pointless, risky procedure.

bjankuski

I have had my screens out for years and I have never had any problems.

I want to point out some disinformation in the last post.

All of the data listed below was obtained on a flow bench at 20.4" of water, std flow point for a holley carb. This data was published by TPIS.

A stock MAF sensor with the screens in flows 529 CFM

A stock 48mm throttle body flows 668 CFM

A MAF sensor with the screens out flows 711 CFM

A MAF sensor with heat sinks removed and no screens flows 750 CFM

The entire stock intake track (filter housing to throttle body) flows 434 CFM

The same system with the screens removed flows 512 CFM

An all stock car will probably not see much of an increase by removing the screens because it does not need the added air flow, but a modified engine can definately benifit from the removal of the screens. It may take some tuning to dial in the combination when you remove the screens but there are gains to be found.

LAFireboyd

iTrader: (3)

But you forgot to mention the 48mm throttle body with an airfoil nearly matches a screenless MAF in airflow with 709cfm. And if you replace the stock airbox with a high-flow filter, like a K&N X-Stream, you'll have a very well-flowing system.

I've had no problems since removing mine either. In fact, to those who've asked if anyone noticed any improvement, YES, the first time I stepped on the gas.

And to the nay-sayers who "know everything" and always think that's just in people's minds(and there's a lot of you on these forums), I've sat in this driver's seat for 17 years--mountains, freeways, cross-country, etc. I'm more sensitive to the "feel" of this car than your #### is to the palm of your hand, lol. And when it reacts differently, no matter how slight, I guarantee you, I know it. So tell it to someone else. And when you've driven your car for as long, then tell me what you think, and maybe I'll pay attention to you.

As for why MAFs fail, as already said, it could be at anytime for any number of reasons. But if one fails right after being modded, then there's a good chance it was damaged in the process.

Ok, I feel better, lol.

wako29

oh, just go to MAP instead







just kidding. A lot of people prefer the MAF system better, but I am doing a crate 350 in a '86 Caprice, and burning my own chips, so MAP is gonna be the way to go for me. Plus, a K&N on the end of the TB look so cool

MikeInAZ

Please do not assume I have provided misinformation because it is in disagreement with TPIS. The reason I did provide it was "because" of TPIS.

Several years ago an article appeared in Hot Rod magazine about this "free" wondrous modification and the sponsor of this article was .... you guessed it.... TPIS.

Ironically they also offered this screen removal fin gutting process as a service for which they charged a good chunk of change. Yep the same suppliers of the super duper throttle body airfoil which does absolutely squat.

They failed to make clear that any performance gains were on an extremely modified engine and a frenzy of "screen cutting" was born.

Sadly the majority of screen cutters had stock TPI engines trying to get a few more HP for free.

When the TPIS data was found to be "questionable" people started looking into their "claims". The whole purpose of the screen removal process was to remove restrictions so the first step was to measure the areas that were not restricted (free area) and size up the most restrictive components.

OEM 48mm throttle body = 2.3323786 in2 per bore,
minus plate and shaft area 4.6648 in2 TOTAL

52mm throttle body = 2.7799564 in2 per bore,
minus plate and shaft area 5.5600 in2 TOTAL

58mm throttle body = 3.5243652 in2 per bore,
minus plate and shaft area 7.0487 in2 TOTAL

Air cleaner housing cover slot = 6.8398 in2

Air cleaner housing top filter opening = 5.7724 in2

8mm drain hole on housing base = 0.076699 in2

TOTAL air cleaner housing openings = 5.849099 in2

Bosch 14094712 MAF = 5.965111 in2 Flow tested and rated at 544 SCFM @0.01"SP

This revealed that the single most restrictive element in this airflow chain was the 48mm throttle body followed by the air box then the 52mm throttle body. Even a 58mm throttle body quickly tapers to 55mm inside the plenum opening all of which are more restrictive components than a stock MAF.

Your throttle body would have to exceed 58mm before the stock MAF even becomes an issue.

The MAF is an extremely delicate and precise component. It allows us to change cams, headers, air intake and "not" have to recalibrate anything as it makes these adjustments for us. It is linked to a chart. If you modify a single component in the MAF then quite basically you will be using a lookup chart that is no longer in correlation to your modified MAF.

Therefore the calibrations it does make will not be correct.

As I said take the air cleaner out of your car and you will get increased airflow..... and for a quite a long time you would be able to say "Haven't had a single problem".

A far safer and much more beneficial free mod would be to modify the air cleaner housing.

Again....... we are (or I am) talking stock engines (the guys that have the most MAF problems). Modified engines are a whole other ball game.

DON 88T/A

The cfm's is a good point,but remember TPI does not care as much about how much air is flowing through the intake as to how fast it is moving because of those long runners...Those screens SLOW down the air big time ...yeah the meter is moving more cfm than the throttle body,but at a terrible pace...that fu@ks up the whole point of having an intake that relies on a low rpm high velocity intake charge...thats why big cams/heads don't work good with long runners...TPI is all velocity ......

DON 88T/A

thats also why these guys just remove the screens and see no gains...because they still have the stock filter housing ,stock plenum,no air foil....If you do a cold air setup,port your plenum,add an air foil and remove the screens you'll see a good gain....if there's one bottleneck in the whole intake track it basically cancels out all the other mods because the velocity is
not being mantained....

mike89-350

my maf went bad I got a new one took the screens out and never had a problem. also I work at a parts store and over half the maf's i sell don't have screens in them.

LAFireboyd

iTrader: (3)

But Mike(inAZ, too many Mikes, lol), when people have an "agenda," as the source of your information apparently had(like many others who don't like TPiS), they'll do and say whatever they have to in order to disprove information. So why should I believe your source either? But since you apparently don't like TPiS, you WANT to believe your source. And that's cool if it works for you.

We read everyday on these forums where one change works well for one person, but a similar change won't work for another. And given everyone's different set-up(as these cars are FAR from being set-up equally by the factory anymore), that's perfectly legitimate. But removing MAF screens have helped, or at least haven't hurt, MANY MANY more people's cars than it's hurt. And it had a positive result with my own car, so I'm inclined to believe that it's safe, and I'm going with TPiS on this.

In general, I experiment for myself and learn from that. I try simple mods, "different" products, or even "snake oils." How else will I know if they really work? By listening to a bunch of people on a message board who claim they're a farce but have no actual knowledge about or experience with them? LOL, no. Unlike them, I don't get on here and speak-up about something I haven't done or a product I haven't tried and profess to be an "expert" about it(see every spark plug topic ever posted, LOL!).

As for the original poster of this topic thread, he's still having trouble with code 33 even after installing the new MAF(see his new topic thread). So his problem was apparently NOT screen-related. Unfortunately, that also means he's still in the dark about it, so I can understand why he feels somewhat bitter. To be in that position really sucks. I hope whatever it is doesn't cost him a car payment or two, and he's up and running again soon.

Guest

Thats completely false.

bjankuski

(OEM 48mm throttle body = 2.3323786 in2 per bore,
minus plate and shaft area 4.6648 in2 TOTAL

52mm throttle body = 2.7799564 in2 per bore,
minus plate and shaft area 5.5600 in2 TOTAL

58mm throttle body = 3.5243652 in2 per bore,
minus plate and shaft area 7.0487 in2 TOTAL

Bosch 14094712 MAF = 5.965111 in2 Flow tested and rated at 544 SCFM @0.01"SP

This revealed that the single most restrictive element in this airflow chain was the 48mm throttle body followed by the air box then the 52mm throttle body. Even a 58mm throttle body quickly tapers to 55mm inside the plenum opening all of which are more restrictive components than a stock MAF.

Your throttle body would have to exceed 58mm before the stock MAF even becomes an issue.)

You basically proved my point with this area comparison, the stock 48mm throttle body does have the smallest area when compared to the stock MAS sensor and it flows 668 CFM. The stock MAS sensor has more area but the screens are restricting the flow and it only flows 529 CFM. When you remove the screens they are no longer a restriction and the sensor now flows 711 CFM because it is larger then the 48MM throttle body. Once you remove the heat sinks the MAS sensor flows 750 CFM. When the screens are in the MAS it is restricting the flow and gains can be had by removing the screens and tuning accordining.

86IROCKET-Z

Me too. I have a MAF from my parts car with a screen, and i gutted the one in my car. I wanna see how this works on my own. If it runs like crap and stalls without the screen, just pop in the screened one.


:hail: :hail: :hail: Parts Cars

LAFireboyd

iTrader: (3)

YAY! Let's hear it for parts cars!!! :hail:

I sure wish I had one. There's a junkyard nearby, but they never have anything good in thirdgens. But one time I got lucky there, and I found a "fresh" '87 TA with a 5.0 TPI still intact! Stupidly, I only took a few parts that I happened to be looking for at the time. The next day, I'm like, geez, go get some of that GOOD STUFF! So I went back, and the entire engine was gone, lol. Oh well...

But 86IROCKET-Z, I had to change the sentence you quoted. I was generalizing at that point, lol. I removed my MAF screens awhile back--and showed improvement.

ghost_man

Do you think that is why my car runs bad? Never idles, barely runs..

when you say you took out the screens....I took EVERYTHNG out...was this wrong?

how did you get a code, my check engine light stuff was all taken out and never put back in. so I don't know if there is a problem or not.

car stalls at every light...takes alot to get it running again....not fun when you have a date with you.

do you think this is my problem? tried to put my trucks in it, buts its a differnet connector.

spearson

omg, yeah, i'd say that is more than likely your problem. Also, is your ALDL connector still under the dash?

87Formula356

when u said everything, did u mean all of the parts ont he inside?

bo ty guy

Nobody has mentioned that even GM started removing the screens in like 01 or something on LS1 cars.

spearson

by design.

ghost_man

YES? THought that is what you did when you port somethign. Few guys at the local hangout said that was holding me back. You mean this has been my problem all along. ? Or do you thing its the holes I drilled in the plastic to allow more air to flow in. THey were only 1/4 inch in about 4 spots...you can really hear it sucking through them.

Someone mentioned an aldl...what is THAT? The connector on the bottom of the MAF?

Might be selling the car and getting something less complicated.

TransAmman87

Dude you messed up bad. Time to go get a new part. I imagine this will help things immensly.

dlp

I pulled the screens 10 years ago, still works fine. I made several back to back wheel dyno runs with a gutted and stock Bosch maf and on my settup the gutted maf added 5-7 rwhp across the board.

MikeInAZ

Personally I am dissapointed in myself. I got suckered into another MAF screen debate and I swore I was done with them......LOL.

BUT.... since we are here.

First... Madmax we been around a long time here. I respect your opinion. Let me reword that statement.

"Impossible to work correctly as it was designed"

Why?

The MAF is a measuring device. Restrictive.... yes it is. So are your injectors, fuel pressure regulator, thermostat and many other components on your car. Restrictive by design for a purpose.

The MAF's purpose? Only one..... to measure.

Based on the MAF having screens, fins and a tiny wire it is calibrated to ground zero. This is tied to a lookup chart.

You add a high flow K & N Filter or a cam or headers. NO PROBLEM. The unmodified MAF senses this increase in flow, looks it up on a chart and makes adjustments accordingly.

The minute you modify the MAF you have modified the measuring device itself.

When you port the MAF housing and/or remove the screens you are causing air to move by the sensors that is not being measured.

It is "calibrated" to measure with screens.

Lower frequency outputs are being read by the lookup charts and the calculations are based on lower than actual airflow.

This makes the ECM lean out the fuel mixture and add timing. Then the oxygen sensors read the lean fuel mixture and bump it back up to compensate for the MAF sensors low readings.

Half of these purported gains are no more than the sensation of a rich fuel mixture like you get when you run a cool engine in the morning of course it feels peppy.

bjankuski reread the numbers. When you bench test a MAF of course you can suck more air through it when you modify it. They don't have it hooked up to a throttle body. The bottleneck is the 48mm throttle body. 4.6in TB vs 5.9 Stock MAF with fins and screens "free area". A stock MAF will outflow a stock throttle body. A modified MAF will outflow a stock MAF but it doesn't matter and it's a moot point if it's hooked to a 48 or 52mm TB.

I am a customer of TPIS. I have not been screwed around by them and don't hold a grudge. I do not agree that they did not make it extremely clear that their tests were done on highly modded engines and that people with stock or near stock would not see these gains, be wasting their money and were at risk of screwing something up. I have no agenda and I'm not selling anything but do firmly believe that info they provided that was at best misleading... at worst totally bogus has screwed up hundreds if not thousands of cars owned by inexperienced folks that have a hard time spitting out a couple of hundred for a new MAF.

Nothing scientific here I was just forced to realize this after a couple of years and dozens upon dozens of emails received from guys that when you went down the diagnostic tree and found "screens removed" you fould the problem with their car.

Once the MAF was replaced their troubles were gone. No one ever wrote me and said..... Hey cut out my screens and my car runs great....... no codes.

I'll say it again.... I'm talking stock engines here. All the hot rodders .... I don't know your set up and won't argue with you. All the guys running with no screens and no problems ..... more power to what works for you.

I'm speaking to the guys that whacked em' out and now have problems. There are plenty of these.

It's hard to ignore...... just search the archives and count the post.

l4cl4c

Ok...Maybe this comment is too simple, but I think the main key here is matching your parts. If your MAF is the highest flowing in the loop I think you MAY have problems with good readings. I have read a few articles that even talk about being sure of "straightening out the air" to ensure an even hit on the sensor.

So if you have a 700CFM MAF and a 600CFM TB how much air will you pull? I think 600CFM, (keeping the velocity stable). So this leads me to think I want a MATCHED system, with the MAF being the lowest flow of the group to ensure good coeverage of the sensor. But lets be real I want it all to flow almost the same.

regardless of what is said the engine needs CFM to match it's pull. Stock 305's may see losses even. 402s massive gains.

Ps....I am running a MAF wire for 60K miles on 355 with 58mm TB with vast imporovements. Same for my brother except 110K miles on his.(Oh yeah....we still are on sreenless stock MAFs.)

I have been wrong before, so let me know by posting corrections. the Truth well set us free. FREE FLOWING!!

l4cl4c

Mike (AZ) is right. It depends. It does measure. And one should consider that for sure. Esspecially if you don't make any changes to your ECU/PROM, TB, Heads, CAM, Headers.

I ran mine stock and tried my brothers first and noticed the difference, so I tried for free. It works for me.

thanks mike

Guest

Now ask yourself how that 'calibration' is done and you'll find that there is nothing that makes recalibration "impossible". Thats why I refuted it, its not true. The calibration itself isnt handled by the MAF at all, I'm 99% sure all they did was try to make the output response as linear as possible, and let the ecm clean up the remainder. Probably why they put the screens in to begin with, it allows the device to be placed in just about any application and have close to the same response, minimizing calibration time once installed and used.

As for the rest of it...

There are lots of mistakes made when viewing the whole system and thinking one component is ok when it might not be. The only intent is to supply the engine with air with as little restriction in doing so as possible. If you get on the filter side of the TB, why restrict this at all? If I start seeing Tornado type arguments, I think I'll step out and forget I read anything here. My biggest complaint with the design is where the last restriction lies. Aside of any problem with the filter and housing design, the last restriction the motor sees is the MAF. This is where the SD guys are screaming, yelling, and praising their setup while calling the MAF setup a piece of junk. Look how much farther away it is. Note that its a definite reduction in flow. This is where the problem comes in. Lets say for example that the MAF can flow 500cfm, and the engine flows 450cfm. Its ok, right? Well, that all depends. How long is the intake tract? Where's the restriction points? Now lets change the rules a bit, and put a 450cfm MAF on there. See any problems yet? You have 1-2' of tubing between the MAF and TB thats reducing the flow, now all of a sudden your 450cfm TB is only able to pull 400cfm of air because thats all thats there. For some people, this becomes a problem. Thats my problem with the 'new' Granatelli 'adjustable' MAF, it doesnt fix that. It doesnt fix the ecm limit either. Doesnt fix much at all, as a matter of fact. May as well save the few bucks and get the Wells MAF instead. What we really need is a physically larger MAF (I could really care less it wont fit the stock intake parts). I'd even take a stock part from another car that would work with our ecm. This should fix just about any restriction we're seeing. Even have screens and fins in it, I dont care, just make it flow 800cfm as is and it will feed just about anything around here adequately. Then someone needs to fix the ecm so there's no more gm/s unit attached to a number 255 anymore. Contrary to popular belief there's no insurmountable limit in the ecm, its just a problem to fix and it is fixable. Once those 2 items are handled, the MAF becomes much less of the 'problem' that those other guys claim it to be.

Well thats enough ranting. I gotta work.

RMK

Who quoted you that price?

GTATransAM

I have no screens, and been running fine for a year plus now. Keep in mind i only drive it summer/spring and not when it rains.

MikeInAZ

Bingo MadMax... keyword recalibration. You are absolutely right. Experienced builders, guru gearheads, PROM burners are going to figure it out and resolve it.

Problem is 98% of screen whackers are beginners looking for a free easy mod and don't know chip reprogramming. I'm not speaking to people that know what they are doing or have heavily modified MAF powerplants. I'm talking to the guys that write me. "I cut my screens, code 33, won't idle, won't run right, surges, dies at idle...... those guys.

If you are a beginner with a stock engine looking for a little kick. Do the air filter housing mod, put in a K & N filter, AFPR and kick the pressure up a bit, have the injectors rebuilt and flowmatched, throw on a cap/coil/rotor kit and some good wires, put in a mild cam maybe some headers. Port the plenum, bump the TPS voltage by .2 drop the stat to a 180° and make sure your 02 and CTS sensors and plugs are good BEFORE you even think about cutting the screens.

You would be suprised at how well that stock MAF responds to those changes.

I am with you. No tornado chasing here. I'm through ranting too.

88TPI406GTA

I agree that cutting the screens on a stock (even slightly modded car) is a waste...

Do not bump the TPS voltage from stock...keep it between .54 and .6 volts...exceeding that will cause problems with the computer...for the stock user of course.