Free Mods

[vortec4800]

I have a GMC with the 4.8L engine, what kind of free mods can I do to give me more performance?

 

Anything would be helpful, and if you could give me general information about the stuff (or even step by step instructions) that would be awesome.

[MountaineerTom]

Probably a good free mod would be to drill some holes in the airbox, to let more air in.  Just be sure not to drill any above where the filter lays. Here's a thread where Mervs posted some pics of the airbox in his S-10 airbox.  Airbox drilling

 

Not sure if the 4.8's are like the 5.3's, but if they are, you could do the throttle body by-pass mod.  Not free, but cost me less than $5.00  Here's the info:Throttle Body By-Pass   Maybe not a good idea if you live in a cold climate area.  The coolant passing through the T-Body would keep it from icing up.  I live in SC, so I don't see that being a problem.  

[sincityZ71]

Yeah the airbox mod is pretty good.  I put some holes in mine to test it out and it seems pretty good, so I am going to pull out the box again soon and drill a bunch more in it.  It is definately a good mod.  

 

Haven't done the bypass mod even though I live in an extremely warm climate here.  Guess I don't feel like having to redo it when I move in a year or two to Nebraska.

[vortec4800]

I live in phoenix arizona, so cold climate is NOT a problem here... I also did the ram-air mod, drilled a big hole in the bottom of the airbox and ran a tube to the bottom valance, seemed to work good - I hear air wooshing through it all the time

[Guest]

IMO, I dont think its worth the time to do the Throttle body bypass... Heres a list of free mods  :arrow: HERE! Consider that several of these can only be done on pre- 2002 engines....  

[sincityZ71]

Well after posting about wanting to put some more holes in my airbox yesterday, I went and did just that last night.  No real good pattern to my drilling but I added a bunch more.  I could still drill somemore, especially on the sides, but I don't want to put to many cause I don't want to make it any easier then I aready have for crud/mud to get in there, especially with the messes I have made under the hood when off-roading.   The new holes added a nice deeper, throatier noise when I step on it too.

[OneFastSilverado]

I don't know if it'll do any good but how about removing the screen from the mass air sensor?  

[TxDoc]

Just a caveat on the MAF removal:

Some info I ran across a while back:

 

Tech Tips

MAF Screen Removal

One Word ~ DON'T

 

Let me start by saying this article is a combination of research available on the internet, my humble opinion, and the following of hundreds of tech post regarding MAF Screen Removal.

 

A few years ago Hot Rod Magazine ran an article on the proposed horsepower gain that could be had for free by the removal of the front and rear MAF Screens. Adding to the resulting screen removal frenzy are companies like TPIS that offer the service of removing the screens and "gutting" the fins, again, for a reported HP gain.

 

The most critical note to be realized (that most don't) is that the engines that these were being used on were heavily modified.

 

The Myth: Across the internet and word of mouth spread the news of this "free mod" and countless pages promoted the technique of MAF Screen Removal without considering some very basic theories and the potential harm of doing this mod. Consequently time after time you will see the post and topics "I removed my screens - now Code 33".

 

The Fact: The MAF Screen Removal Process WILL NOT CREATE horsepower within itself. It can only in the right conditions FREE UP horsepower that ALREADY EXIST and only under certain conditions.

Why?

1. Your stock MAF with screens will outflow your stock 48mm throttle body.

2. It will even outflow a 52mm throttle body.

3. It will also outflow your stock intake.

 

This Means: that if you are still using these stock components your MAF screen removal process is totally wasted and potentially (code 33) dangerous and could cost $100.00 + if you screw it up. The MAF has to be the most restrictive element in your chain of flow to even possibly make the mod worth anything and ONLY if you already have the horsepower to free up by a modified throttle body and intake.

 

Why the Screens?

 

What kicks me in the pants is not only do I personally feel that these screens are the single most important part of the MAF but that they serve multiple purposes. The screen in the front filters potential debris, prevents something from being dropped into the MAF when working on car, a tool slipping, etc., and the rear screen not only serves the same protective service but it also helps cushion potential damages to the fragile MAF wire that can be caused by a backfire under lean conditions. And these services are secondary to their primary purpose which is to regulate airflow for measuring purposes.

 

Are the Screens Restrictive?

 

Absolutely they are, but by design. Is your voltage regulator restrictive? Is your air cleaner restrictive? Is your fuel filter restrictive? Are your fuel injectors restrictive? Is your fuel pressure regulator restrictive? Yes they are.....by design. Would you remove your air cleaner or fuel filter? We are blessed with the common sense that although restrictive we find these components necessary for proper operation and to remove them would be foolish or asking for trouble. It is very unfortunate that we don't possess the same common sense regarding the MAF sensor.

 

Theory of Operation

 

Understand two terms first of all. Turbulent Airflow and Laminar Airflow. They are opposites. Without definition we can identify with "turbulent" but "laminar" airflow would define as "smooth, straightened out, regulated".

 

To help understand some conflicting articles I will point out an important factor here right away. There is no such thing as turbulence free airflow. Airflow is a "fluid flow" and a fluid flowing past obstructions, against boundaries, even the composition of the fluid itself in different densities and pressures create turbulences that can't be removed. So when we speak of Laminar Airflow being smoothed out and being the opposite of turbulent airflow we're speaking of a "controlled turbulence" vs. "uncontrolled turbulence".

 

Envision this process by thinking of your kitchen faucet. The little screen on the end. Take it out and watch your water flow increase but also notice it splash around and surge. You can see the uneven flow very easily. Put the aerator back in and see it smooth out in a more regulated even flow. Look at the end of most hair dryers and they will have a screen in them. Of course this is to prevent getting your hair sucked up in there and catching your head on fire BUT it also disperses the air in a more even, regulated pattern. Think of the construction of a dam on a river. You KNOW it is restrictive. It "holds back" the natural flow of water and regulates it to a desired given amount. Why? To do something productive with the process of flow. Just like your MAF screens.

 

The MAF Process

 

I am going to chop this section down to the most basic of processes. GM didn't invent this process, as a matter of fact it is the same process used by the weather industry to measure "chill factor" so it's theory was utilized by GM not invented by them.

 

1. You have a small wire inside your MAF which can be heated.

2. It is calibrated at zero airflow to be a certain temperature.

3. Air flowing across the wire cools it off. The more air flow the cooler the wire.

4. A voltage is supplied to that wire to keep it at a constant temperature. The more air flowing, the cooler the wire, the more voltage required to keep it the same temp.

5. This voltage fluctuation is a measurable, readable function which when converted to a digital output can be used for calibrations of airflow entering your intake.

6. These calibrations are referenced to a lookup table stored in your ECM and based on these fluctuations various functions of your engine are controlled based on the amount of airflow you are encountering.

 

The screens are there simply to provide a steady, stable, regulated environment for the most precise calculations available.

 

Now I will point you back to one of my previous "goofy-assed" examples and ask: Would it be easier to count the number of gallons that flow past a certain point in the river ...with the dam or without it? That is what your screens are for... to establish "near as possible" level playing field ground zero reference point for calibrations.

 

What Happens When They are Removed

 

Without the screen, the computer can not take a correct reading on how much air is entering the engine. 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. 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.

 

In Summary I would say that I have heard of people making this mod and not having trouble codes. I have also heard of reported gains in performance. In both of these situations, if true, you have my respect and congradulations. But I have never seen proof of these gains especially on a stock setup. I have however lost count of the number of post that are encountering trouble after making this "free" mod. Further I would say that if the horsepower is not there in the first place your sure not going to create any new horsepower cutting out your screens.

 

The MAF is a truly unique and awesome device that allows us to drive in different environments (altitudes) with no intake modifications. Allows us to make "other" performance mods without having to calibrate a new PROM. To butcher it and make it less accurate and precise just doesn't make sense to me.

 

1. If you are driving a stock intake car this mod will do absolutely nothing for you.

2. If you have such a heavily modified engine that it would make a difference Why are you using the MAF system anyway? .....you should be on Speed Density with a custom chip.

 

My personal disclaimer is this. If you have already cut your screens out I am not saying your stupid or you did something bad. I am saying that maybe you were misinformed or that there was a lack of information available to make the best possible decision for your situation. This article is not to point out mistakes, make fun of, or even say "I'm right ~ you're wrong". But merely to present an opposing view, a difference of opinion, and possibly a closer understanding of a mysterious, complex component.

 

MAF Screen Removal

 

 

 

The Mass Air Flow (MAF) Sensor is located between the air filter assembly and the intake Bellows, and it's name implies it's function. It measures the amount (mass) of air entering the engine during operation, and uses this information to (in part) determine the correct air/fuel mixture for the conditions.

The MAF is an excellent sensor in that it has the ability to measure four different characteristics of the incoming air simultaneously: temperature, pressure, volume, and humidity. This ability give the fuel management system remarkable flexibility and adaptability. One drawback, however is the MAF represents a significant restriction to air flow into the engine. In stock trim the MAF can flow around 529 cfm maximum - OK for stock applications, but not if any modifications are performed.

The major restriction is the "debris screen". It is meant to protect the delicate heated wire, but to you its purpose is to keep your car from GOING FASTER.

Fortunately, there is a relatively simple modification that can be done to net larger gains in air flow - up to 180 cfm in most cases, and usually more.

Before we begin, see the CMA statement again: located on the main mods page.

First unplug the MAF, and remove it from the car. Place the sensor on a firm, flat surface. You will notice that the screen is held in with a metal or plastic ring that is glued or fitted into a bore (grove) on the wall of the MAF housing. Using a sharp tool of some type (small knife or screwdriver) work under the ring until you can wedge the tool between the ring and the bore. Take your time - it is very easy to slip and damage something. Then, work your way around the ring, carefully prying it away. The metal ring will just pop out and the plastic one may crack. At this point you will know you've won this round.Next, use the tool to work the screen out in a way similar to the ring. This shouldn't be difficult. Simple, eh? You can use the tool to carefully remove any pieces of the plastic ring or glue that might be left stuck in the MAF.

Some OE MAFs may have two screens, so do the same procedure on both ends. Some after market MAF units have only one screen.

You've just gained about 180 cfm in about 10 minutes or less. And most of that time will be spent putting the air box back together.

No noticeable power gain was detected. But there was a slight increase in exhaust tone at ideal and throttle and I seem to be getting better gas mileage.

 

Not telling you not to do it, but others have tried it.

[tweaker]

FOURWHEELER magazine listed descreening your MAF in a GM truck as #7 in a list of 10 inexpensive modifications.  I have descreened at least 8 GM vehicals without ever triggering any error codes.  Descreening seems to work well in conjuction with an aftermarket air intake & free flow exhaust system.  

 

Descreening by it's self only seems to hurt performance and MPG in the new 2003 5.3Ls.  I just descreened my new '03 (without any other performance improvements; other than an Amsoil air filter).  Throttle response is worse (bogs down) and my mpg dropped a couple of tenths.  My maximum best mpg at 55mpg is off by several mpg.  Note: this is after a few hundred miles.  It was even worse at first & I reset the computer before driving.

 

I'm not happy I descreened at this point.  I fact, I'm going to order a new MAF (whew - only $66.00 @ gmpartsdirect).  After I install a "free flow" intake and exhaust, I'll try the descreened MAF and then screened MAF for 1,000 miles each and record mpg as well as note engine response.

 

I'll post my findings in a few months...

[Zane]

i took the MAF off my 95 Corvette. Added a few ponies and didn't set and codes.

[HvyChevyZ71]

ive descreened mine and 3 other on 5.7 vortecs and 1 on a friends 5.3 vortec, all with good results not one problem.  def. not a very noticeable mod but every little bit helps.  I didnt read all through the posts but the EGR mod is another freebie that alot of folks have done on the newer engines.

[CMNTMXR81]

Just a caveat on the MAF removal:

Some info I ran across a while back:

 

Tech Tips

MAF Screen Removal

One Word ~ DON'T

 

Let me start by saying this article is a combination of research available on the internet, my humble opinion, and the following of hundreds of tech post regarding MAF Screen Removal.

 

A few years ago Hot Rod Magazine ran an article on the proposed horsepower gain that could be had for free by the removal of the front and rear MAF Screens. Adding to the resulting screen removal frenzy are companies like TPIS that offer the service of removing the screens and "gutting" the fins, again, for a reported HP gain.

 

The most critical note to be realized (that most don't) is that the engines that these were being used on were heavily modified.

 

The Myth: Across the internet and word of mouth spread the news of this "free mod" and countless pages promoted the technique of MAF Screen Removal without considering some very basic theories and the potential harm of doing this mod. Consequently time after time you will see the post and topics "I removed my screens - now Code 33".

 

The Fact: The MAF Screen Removal Process WILL NOT CREATE horsepower within itself. It can only in the right conditions FREE UP horsepower that ALREADY EXIST and only under certain conditions.

Why?

1. Your stock MAF with screens will outflow your stock 48mm throttle body.

2. It will even outflow a 52mm throttle body.

3. It will also outflow your stock intake.

 

This Means: that if you are still using these stock components your MAF screen removal process is totally wasted and potentially (code 33) dangerous and could cost $100.00 + if you screw it up. The MAF has to be the most restrictive element in your chain of flow to even possibly make the mod worth anything and ONLY if you already have the horsepower to free up by a modified throttle body and intake.

 

Why the Screens?

 

What kicks me in the pants is not only do I personally feel that these screens are the single most important part of the MAF but that they serve multiple purposes. The screen in the front filters potential debris, prevents something from being dropped into the MAF when working on car, a tool slipping, etc., and the rear screen not only serves the same protective service but it also helps cushion potential damages to the fragile MAF wire that can be caused by a backfire under lean conditions. And these services are secondary to their primary purpose which is to regulate airflow for measuring purposes.

 

Are the Screens Restrictive?

 

Absolutely they are, but by design. Is your voltage regulator restrictive? Is your air cleaner restrictive? Is your fuel filter restrictive? Are your fuel injectors restrictive? Is your fuel pressure regulator restrictive? Yes they are.....by design. Would you remove your air cleaner or fuel filter? We are blessed with the common sense that although restrictive we find these components necessary for proper operation and to remove them would be foolish or asking for trouble. It is very unfortunate that we don't possess the same common sense regarding the MAF sensor.

 

Theory of Operation

 

Understand two terms first of all. Turbulent Airflow and Laminar Airflow. They are opposites. Without definition we can identify with "turbulent" but "laminar" airflow would define as "smooth, straightened out, regulated".

 

To help understand some conflicting articles I will point out an important factor here right away. There is no such thing as turbulence free airflow. Airflow is a "fluid flow" and a fluid flowing past obstructions, against boundaries, even the composition of the fluid itself in different densities and pressures create turbulences that can't be removed. So when we speak of Laminar Airflow being smoothed out and being the opposite of turbulent airflow we're speaking of a "controlled turbulence" vs. "uncontrolled turbulence".

 

Envision this process by thinking of your kitchen faucet. The little screen on the end. Take it out and watch your water flow increase but also notice it splash around and surge. You can see the uneven flow very easily. Put the aerator back in and see it smooth out in a more regulated even flow. Look at the end of most hair dryers and they will have a screen in them. Of course this is to prevent getting your hair sucked up in there and catching your head on fire BUT it also disperses the air in a more even, regulated pattern. Think of the construction of a dam on a river. You KNOW it is restrictive. It "holds back" the natural flow of water and regulates it to a desired given amount. Why? To do something productive with the process of flow. Just like your MAF screens.

 

The MAF Process

 

I am going to chop this section down to the most basic of processes. GM didn't invent this process, as a matter of fact it is the same process used by the weather industry to measure "chill factor" so it's theory was utilized by GM not invented by them.

 

1. You have a small wire inside your MAF which can be heated.

2. It is calibrated at zero airflow to be a certain temperature.

3. Air flowing across the wire cools it off. The more air flow the cooler the wire.

4. A voltage is supplied to that wire to keep it at a constant temperature. The more air flowing, the cooler the wire, the more voltage required to keep it the same temp.

5. This voltage fluctuation is a measurable, readable function which when converted to a digital output can be used for calibrations of airflow entering your intake.

6. These calibrations are referenced to a lookup table stored in your ECM and based on these fluctuations various functions of your engine are controlled based on the amount of airflow you are encountering.

 

The screens are there simply to provide a steady, stable, regulated environment for the most precise calculations available.

 

Now I will point you back to one of my previous "goofy-assed" examples and ask: Would it be easier to count the number of gallons that flow past a certain point in the river ...with the dam or without it? That is what your screens are for... to establish "near as possible" level playing field ground zero reference point for calibrations.

 

What Happens When They are Removed

 

Without the screen, the computer can not take a correct reading on how much air is entering the engine. 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. 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.

 

In Summary I would say that I have heard of people making this mod and not having trouble codes. I have also heard of reported gains in performance. In both of these situations, if true, you have my respect and congradulations. But I have never seen proof of these gains especially on a stock setup. I have however lost count of the number of post that are encountering trouble after making this "free" mod. Further I would say that if the horsepower is not there in the first place your sure not going to create any new horsepower cutting out your screens.

 

The MAF is a truly unique and awesome device that allows us to drive in different environments (altitudes) with no intake modifications. Allows us to make "other" performance mods without having to calibrate a new PROM. To butcher it and make it less accurate and precise just doesn't make sense to me.

 

1. If you are driving a stock intake car this mod will do absolutely nothing for you.

2. If you have such a heavily modified engine that it would make a difference Why are you using the MAF system anyway? .....you should be on Speed Density with a custom chip.

 

My personal disclaimer is this. If you have already cut your screens out I am not saying your stupid or you did something bad. I am saying that maybe you were misinformed or that there was a lack of information available to make the best possible decision for your situation. This article is not to point out mistakes, make fun of, or even say "I'm right ~ you're wrong". But merely to present an opposing view, a difference of opinion, and possibly a closer understanding of a mysterious, complex component.

 

MAF Screen Removal

 

 

 

The Mass Air Flow (MAF) Sensor is located between the air filter assembly and the intake Bellows, and it's name implies it's function. It measures the amount (mass) of air entering the engine during operation, and uses this information to (in part) determine the correct air/fuel mixture for the conditions.

The MAF is an excellent sensor in that it has the ability to measure four different characteristics of the incoming air simultaneously: temperature, pressure, volume, and humidity. This ability give the fuel management system remarkable flexibility and adaptability. One drawback, however is the MAF represents a significant restriction to air flow into the engine. In stock trim the MAF can flow around 529 cfm maximum - OK for stock applications, but not if any modifications are performed.

The major restriction is the "debris screen". It is meant to protect the delicate heated wire, but to you its purpose is to keep your car from GOING FASTER.

Fortunately, there is a relatively simple modification that can be done to net larger gains in air flow - up to 180 cfm in most cases, and usually more.

Before we begin, see the CMA statement again: located on the main mods page.

First unplug the MAF, and remove it from the car. Place the sensor on a firm, flat surface. You will notice that the screen is held in with a metal or plastic ring that is glued or fitted into a bore (grove) on the wall of the MAF housing. Using a sharp tool of some type (small knife or screwdriver) work under the ring until you can wedge the tool between the ring and the bore. Take your time - it is very easy to slip and damage something. Then, work your way around the ring, carefully prying it away. The metal ring will just pop out and the plastic one may crack. At this point you will know you've won this round.Next, use the tool to work the screen out in a way similar to the ring. This shouldn't be difficult. Simple, eh? You can use the tool to carefully remove any pieces of the plastic ring or glue that might be left stuck in the MAF.

Some OE MAFs may have two screens, so do the same procedure on both ends. Some after market MAF units have only one screen.

You've just gained about 180 cfm in about 10 minutes or less. And most of that time will be spent putting the air box back together.

No noticeable power gain was detected. But there was a slight increase in exhaust tone at ideal and throttle and I seem to be getting better gas mileage.

 

Not telling you not to do it, but others have tried it.

I've descreened every MAF in my fleet of vehicles with nary a problem!

 

It's not a horsepower adder, it helps make throttle response sharper if anything.

 

Those screens are put there to straighten airflow with STOCK intakes which includes all the factory baffling, silencers, extra bends, etc, etc when the airflow prior to the MAF is turbulent because of all that.

 

When you put a CAI or other modified intake on a vehicle, it generaly removes all baffling, silencers, extra bends, etc, therefore providing a much more straight and less turbulent air stream.  Having a screen now restricts that straighter, less turbulent airflow.

 

Like I said, I've had about 10 GM vehicles with MAF's that I've removed them all in with nary a problem and much better throttle response as a result.