DIY Hiflow MAF Sensor Mod

[phathom]

CAUTION: THIS HAS NOT BEEN TESTED ON A STOCK CAR. PERFORMING THIS ON A STOCK CAR MAY AFFECT YOUR IDLE AND PERFORMANCE. PERFORM THIS MODIFICATION AT YOUR OWN RISK.
However, if you do this on a stock car, please post your results here.

I was reading on some other forums about how people have gotten some more power out of their engines. Well one way of course is swapping your MAF for one that flows better. Another method they talked about is modding your MAF so it has less restriction. Someone with a 330 actually did this mod and dynod it before and after with 3 runs a piece and had gotten a HP/TQ gain of 7-9HP and 5-8TQ. So I decided to take on the mod myself and give it a try as well as do a write up.

Tools: Flathead screwdriver, needle nose pliers
Time:5-10 minutes
Difficulty:2/10

1: Pop your hood (duh, if you can't do this STOP NOW)
2: Loosen the 2 screws on the clamps that hold either end of the intake piping to the MAF sensor.
3: Gently pop the metal clip up that holds the wiring to the sensor and gently remove the wiring from the sensor.
4: Remove the MAF sensor from the piping
5: Take the needle nose pliers and remove the 2 screens. The first one in front is a little stubborn, don't twist or you'll break them, just get a good grip and pull straight out. The Second one in the back is a piece of cake and easier to grab. Make sure when your doing this you don't touch or damage the sensor hanging down.
6: This would be a good time to use some MAF cleaner or electrical contact cleaner to clean the sensor before reassembling.
7: Follow the instructions backwards to reassemble.

http://i109.photobucket.com/albums/n54/phathomthis/Mafmod1.jpg
http://i109.photobucket.com/albums/n54/phathomthis/Mafmod2.jpg

The purpose of these screens is to stabilize airflow to get a more accurate reading to that sensor, however this also restricts the air flow. After doing this mod, I have noticed a lot quicker throttle response and a little quicker acceleration and no change in gas mileage. The only "negative" thing I'd say about this, is that you have the "risk" of something hitting the sensor, but let's face it the grates in the screens you remove are a lot bigger than your air filter so if something gets through your air filter, it's not going to do much anyway. You have a bigger risk of hitting the sensor and messing it up with your pliers during the install than this happening.

When I first installed this, the first time I reved the engine it reved up quicker but took hung on reving down between 1500-1000rpm. This only happened the first time I reved it, after driving it on a short trip it has "adapted" and have not had an issue since.
On a side note, I did have a SES on when I did this mod (P1624) and it cleared as soon as I started the car after doing the mod. That code has came and gone and I think it was related to my HIDs as it came on and off ever since I installed them, but it could be this, or just a coincidence.

[Paintballistic]

was there a thread on this before?

[creeves328]

There are some threads on this, best to do a google.

In general, fluid dynamics and harmonic cancellation are the principles behind their purpose. FD wise, its possible you will experience a lean condition at high RPM by removing the screen. This all depends on the Reynolds number of the intake you have. Harmonics wise, the screens cancel out the pressure wave reversion, which means you may see more pronounced torque peaks/valleys on a dyno occurring throughout the rev range.

1500-1000rpm increase, guessing its due to vortex breakdown (beginning of turbulence) on the MAF sensor. Rich/Lean/Rich/Lean

Should you do it? It very likely will increase peak HP, but may hurt overall acceleration. All depends on the car and its installed intake.

[JackEatsEmoKids]

Good Job

You just ruined something that was well engineered to do it's job.

And that HP gain is BS. To properly do a dyno run means get the car on their and get it as hot as possible. Heat soak it,then run it. That's real dyno numbers. Then put in your new mods and get it hot again and try again. If the power doesn't increase, you just wasted your time.

[phathom]

1500-1000rpm increase, guessing its due to vortex breakdown (beginning of turbulence) on the MAF sensor. Rich/Lean/Rich/Lean

Should you do it? It very likely will increase peak HP, but may hurt overall acceleration. All depends on the car and its installed intake.

The 1500-1000 RPM stall was only after it was first installed, it doesn't have any lag whatsoever now. Just quicker revs and faster acceleration.


Good Job

You just ruined something that was well engineered to do it's job.

And that HP gain is BS. To properly do a dyno run means get the car on their and get it as hot as possible. Heat soak it,then run it. That's real dyno numbers. Then put in your new mods and get it hot again and try again. If the power doesn't increase, you just wasted your time.
Heat soak does not equal a valid dyno run comparison. Same operating conditions before mod and after mod do. Such as if it was heatsoaked before the mod, and heatsoaked after the mod. Or if it was not heatsoaked before and not heatsoaked after. Also 5 minutes to do the mod is not a big deal if for some reason it didn't.

BTW: Even if you are correct and there is 0 power increase, ever since I did this, acceleration, in addition to being quicker and more responsive is also sooooo much smoother. To me that, makes it worth it even if there were no power gains. Also it could be just on mine with my mods (intake, chip, exhaust) that the product of performance is greater than the sum of it's parts.

[creeves328]

Phantom - Any plans to get a dyno run done? I'd be interested in the A/F ratio changes throughout the rev range.

[pob000]

yes another free mod. Tks

[phathom]

Phantom - Any plans to get a dyno run done? I'd be interested in the A/F ratio changes throughout the rev range.
Possibly, I'm leaving for vacation in a couple day to california, last time I averaged 33mpg down there and 30mpg back. I can report back what my mileage is here and see how it compares. I'm really curious to see how it runs in a 1/4 mile and what the dyno numbers are, because as it is, it's a 323 that off the line and on freeway rolls beats 325s, 328s, and stays almost dead even with 330s although they get me off the jump.

[neil1138]

Possibly, I'm leaving for vacation in a couple day to california, last time I averaged 33mpg down there and 30mpg back. I can report back what my mileage is here and see how it compares. I'm really curious to see how it runs in a 1/4 mile and what the dyno numbers are, because as it is, it's a 323 that off the line and on freeway rolls beats 325s, 328s, and stays almost dead even with 330s although they get me off the jump.

Suuure. Let me start out by saying that I read this thread right after the OP posted it but i didn't want to jump in and make him look like a tool. But since most everyone here has already begun, let me join in on the fun.

I read a long time back that the mesh screens on the MAF are designed to straighten the air flowing over the maf sensor. Taking it out and you can easily mess it up (search E46Fanatics and you'll see people saying "my car is stuttering/running like crap" after they take the screen out.) Whatever gain you would gain by taking it out would be negligible. You'd get more hp from putting a sticker on your car.

And going back to you beating 325s, 328s and 330s... care to explain that? Because I guarantee that I could beat you on a highway roll. Even if you got 10hp from this "mod" it wouldnt put you anywhere in the range of beating 328s and 330s. Oh, and btw, nice mods list.

I think my reputation proceeds me

[mkodama]

I read a long thread on this before. It started out the exact same way as this one as well. But in the end, the people who removed this screen just ended up with broken MAF sensors and engine codes, as well as there was never any documented increase in power.

[neil1138]

I read a long thread on this before. It started out the exact same way as this one as well. But in the end, the people who removed this screen just ended up with broken MAF sensors and engine codes, as well as there was never any documented increase in power.

word

[Windsma]

I like stickerHP....



Ive done it to my 3000gt MAF, it was more the honeycomb style. It was noticeable but prob no real hp gain.
Never any problems w/ idle or acceleration.

[phathom]

I read a long time back that the mesh screens on the MAF are designed to straighten the air flowing over the maf sensor. Taking it out and you can easily mess it up (search E46Fanatics and you'll see people saying "my car is stuttering/running like crap" after they take the screen out.) Whatever gain you would gain by taking it out would be negligible. You'd get more hp from putting a sticker on your car.

And going back to you beating 325s, 328s and 330s... care to explain that? Because I guarantee that I could beat you on a highway roll. Even if you got 10hp from this "mod" it wouldnt put you anywhere in the range of beating 328s and 330s. Oh, and btw, nice mods list.

You are correct in the purpose of the mesh screens, I did also state that in the original post.

Well I made it here to California, driving spiritedly through the hills to get here with a/c on averaged 32mpg on the drive down here. Not too shabby being my car is said to get 28mpg highway and last trip I got 33 with no a/c and sitting on cruise the whole time. Acceleration nice and peppy, still quick revs, very smooth, no codes at all or any problems with idle, acceleration, or anything.

As far as performance goes, with mods, minus this one, in actual races against stock 325s, 328s, and 330s, both off a light and from freeway rolls. I beat 325s no problem, 328s is a pretty even start and then I normally start walking past them, and 330s (non ZHP) they get me on the start but don't pull any more after that, I stay dead even with them about 3/4 a car length back with my fender to their rear quarter panel. This is against stock E46s and mine modded of course. I'm not saying a 325, 328, or definitely a 330 with the same or more mods than I have wouldn't rip me a new one. But I am saying that with my car modded vs those cars stock that is how it measures up.

[creeves328]

I read a long time back that the mesh screens on the MAF are designed to straighten the air flowing over the maf sensor. Taking it out and you can easily mess it up...

The airflow inside the tube is fastest in the center, slowest on the sides. The screens slow down the air flow velocity throughout the pipe, which makes the center/side difference less of a difference. Since the MAF sensor isn't measured at different points in the pipe, this gives a more accurate measurement for total CFM. Air temp is also measured, just FYI.

The screens also attempt to cancel (better said lessen) the pressure waves from the intake valves. You would think as RPM increases, the CFM consumption of an engine would be near linear. Generally speaking, the path is similar, but CFM has peaks/valleys as a result of pressure wave reversion. The screens will help level out those extremes to some point. Key word being help, the real solution for harmonics cancellation is a better intake.

Would removing the screens help performance? Depends. Example -- Lets say you remove the screens and measure flow independently of the MAF; your readings show 3% total CFM increase @ 5500 RPM, 5% increase @ 6500 RPM. Now the MAF will likely measure 5% more @ 5500, 8% more @ 6500 RPM. Why? The airflow being fastest in the center isn't slowed.

This is why I was asking for a dyno with A/F ratio measures.


I think my reputation proceeds me

Yes it does. Hehe... sorry dude, you set yourself up for that.:)

[neil1138]

The airflow inside the tube is fastest in the center, slowest on the sides. The screens slow down the air flow velocity throughout the pipe, which makes the center/side difference less of a difference. Since the MAF sensor isn't measured at different points in the pipe, this gives a more accurate measurement for total CFM. Air temp is also measured, just FYI.

The screens also attempt to cancel (better said lessen) the pressure waves from the intake valves. You would think as RPM increases, the CFM consumption of an engine would be near linear. Generally speaking, the path is similar, but CFM has peaks/valleys as a result of pressure wave reversion. The screens will help level out those extremes to some point. Key word being help, the real solution for harmonics cancellation is a better intake.

Would removing the screens help performance? Depends. Example -- Lets say you remove the screens and measure flow independently of the MAF; your readings show 3% total CFM increase @ 5500 RPM, 5% increase @ 6500 RPM. Now the MAF will likely measure 5% more @ 5500, 8% more @ 6500 RPM. Why? The airflow being fastest in the center isn't slowed.

This is why I was asking for a dyno with A/F ratio measures.



Yes it does. Hehe... sorry dude, you set yourself up for that.:)

lol what? I'll dumb it down for you guys. There is a 17 page thread over on E46Fanatics about this and al that was found was that the screen "mod" only lead to broken MAF sensors and minimal if any butt dyno gains.

Like stated by mkodama who is another highly regarded member on E46Fanatics.


I read a long thread on this before. It started out the exact same way as this one as well. But in the end, the people who removed this screen just ended up with broken MAF sensors and engine codes, as well as there was never any documented increase in power.

[phathom]

The airflow inside the tube is fastest in the center, slowest on the sides. The screens slow down the air flow velocity throughout the pipe, which makes the center/side difference less of a difference. Since the MAF sensor isn't measured at different points in the pipe, this gives a more accurate measurement for total CFM. Air temp is also measured, just FYI.

The screens also attempt to cancel (better said lessen) the pressure waves from the intake valves. You would think as RPM increases, the CFM consumption of an engine would be near linear. Generally speaking, the path is similar, but CFM has peaks/valleys as a result of pressure wave reversion. The screens will help level out those extremes to some point. Key word being help, the real solution for harmonics cancellation is a better intake.

Would removing the screens help performance? Depends. Example -- Lets say you remove the screens and measure flow independently of the MAF; your readings show 3% total CFM increase @ 5500 RPM, 5% increase @ 6500 RPM. Now the MAF will likely measure 5% more @ 5500, 8% more @ 6500 RPM. Why? The airflow being fastest in the center isn't slowed.

This is why I was asking for a dyno with A/F ratio measures.



Yes it does. Hehe... sorry dude, you set yourself up for that.:)

Thank you, I'm glad you can shed some light on how the dynamics of intake pressure work in regards to this.

I am going to have it dyno'd after I get back from vacation, as well as taking my car to the local strip here legal drags and get some quarter mile times and post them up here. This will be the true testament if this has improvement at all, and what affect, if any it has on the AFR.

I have had several cars before with MAF sensors, and none of them had this screen before, just filter, MAF, intake. So I doubt that this screen is that great of a help in performance or economy if any. I think I proved just in mpg that the help in fuel economy isn't there considering I got only 1 MPG less than last trip, and this trip had the a/c on the whole time, where last trip it was purely cracked windows and tilted sunroof since it wasn't as hot.

I think some of the people may have had who had done this mod before and had problems either A) Did it on a stock car, with a stock intake, or perhaps even a stock DME. B) While taking the screens out, weren't as careful and might have knocked the sensor with the pliers and messed something up (not that hard to do since it's right there).

As said, the only time it acted funny, was the first time I started it up and reved it to about 4k just to see if there was any difference in response, and it hung dropping from 1500-1000, this was ONLY THE FIRST TIME I reved it, after that it never happened again. Drove it to the store and back and tried it again and have since and no issues whatsoever.

Without the proper research and saying that anyone who does this mod will screw up their car is just ignorant. It's almost like saying anyone who puts a turbo on their car will blow the engine, or anyone who drifts will total their car. Yes it is possible, but with the right car, and with it done right (supporting mods, preparation, technique) it can be a good thing and not harmful. Any mod you do on your car, if not done right, or with other mods needed to support it can be a waste of time and/or even harmful on the car. You wouldn't install a BOV on a car without a turbo or a turbo on a car without the wastegate would you? For this mod, and from the input I'm getting (although all negative input here is heresay, no one that has done this has posted, or at least said they've done it). From this it seems like you need at least an aftermarket intake, and possibly a reflashed/tuned DME. However without someone who has done it on a stock car posting, we can't be sure of how this plays out on a stock car.

[E30nSC]

Creeves...so you're saying that the MAF could possibly read an erroneous increase in flow due to the differences in velocity? If the MAF read high, wouldn't that cause a slight "rich" condition, as opposed to "lean?" Just wanting to understand...

I have a bone stock '93 325i...well, except for the K&N panel filter. Would you expect an improvement given the car's "stockness?"

I do agree with Phantom on the "sum of it's parts" theory. My previous car ('93 Civic Si) had many low-buck mods. No dyno runs, but a tremendous MPG improvement.

Bone stock (when purchased) the car averaged 33-35 MPG. After a few low-buck mods (K&N, slightly modified stock airbox, cat-back, better ignition wires, PROPERLY adjusted valves, syn. fluids throughout, etc.,) I averaged 42 MPG.

Little improvements can add up...I just wanna make sure this is really one of them. ;)

[phathom]

Creeves...so you're saying that the MAF could possibly read an erroneous increase in flow due to the differences in velocity? If the MAF read high, wouldn't that cause a slight "rich" condition, as opposed to "lean?" Just wanting to understand...

I have a bone stock '93 325i...well, except for the K&N panel filter. Would you expect an improvement given the car's "stockness?"

I do agree with Phantom on the "sum of it's parts" theory. My previous car ('93 Civic Si) had many low-buck mods. No dyno runs, but a tremendous MPG improvement.

Bone stock (when purchased) the car averaged 33-35 MPG. After a few low-buck mods (K&N, slightly modified stock airbox, cat-back, better ignition wires, PROPERLY adjusted valves, syn. fluids throughout, etc.,) I averaged 42 MPG.

Little improvements can add up...I just wanna make sure this is really one of them. ;)

Agreed, I have already proven on an extremely long drive that it doesn't affect MPG negatively, possibly slightly positively. Your car is pretty stock and we haven't heard anything from someone who has done this on a stock car, only I heard from a friend, or I read somewhere. So if you want to do this and post results that'd be great. Just make sure you don't hit the sensor while pulling the screens and let us know how it turns out. I'm curious to see how it acts on a car without aftermarket intake and flashed dme.

[neil1138]

Thank you, I'm glad you can shed some light on how the dynamics of intake pressure work in regards to this.

I am going to have it dyno'd after I get back from vacation, as well as taking my car to the local strip here legal drags and get some quarter mile times and post them up here. This will be the true testament if this has improvement at all, and what affect, if any it has on the AFR.

I have had several cars before with MAF sensors, and none of them had this screen before, just filter, MAF, intake. So I doubt that this screen is that great of a help in performance or economy if any. I think I proved just in mpg that the help in fuel economy isn't there considering I got only 1 MPG less than last trip, and this trip had the a/c on the whole time, where last trip it was purely cracked windows and tilted sunroof since it wasn't as hot.

I think some of the people may have had who had done this mod before and had problems either A) Did it on a stock car, with a stock intake, or perhaps even a stock DME. B) While taking the screens out, weren't as careful and might have knocked the sensor with the pliers and messed something up (not that hard to do since it's right there).

As said, the only time it acted funny, was the first time I started it up and reved it to about 4k just to see if there was any difference in response, and it hung dropping from 1500-1000, this was ONLY THE FIRST TIME I reved it, after that it never happened again. Drove it to the store and back and tried it again and have since and no issues whatsoever.

Without the proper research and saying that anyone who does this mod will screw up their car is just ignorant. It's almost like saying anyone who puts a turbo on their car will blow the engine, or anyone who drifts will total their car. Yes it is possible, but with the right car, and with it done right (supporting mods, preparation, technique) it can be a good thing and not harmful. Any mod you do on your car, if not done right, or with other mods needed to support it can be a waste of time and/or even harmful on the car. You wouldn't install a BOV on a car without a turbo or a turbo on a car without the wastegate would you? For this mod, and from the input I'm getting (although all negative input here is heresay, no one that has done this has posted, or at least said they've done it). From this it seems like you need at least an aftermarket intake, and possibly a reflashed/tuned DME. However without someone who has done it on a stock car posting, we can't be sure of how this plays out on a stock car.

http://forum.e46fanatics.com/showthread.php?t=38959&highlight=maf+screens

Read up buddy. 17 pages. Starts out the same way as you and then progresses to people with broken MAFs and no performance gains. Even VERY reputable sponsors and tuners such as Active Autowerks and UUC advise members not to take out the screen.

EDIT: Went back and read your original post, and noticed that you added a little fine print. Lets see what it says...


On a side note, I did have a SES on when I did this mod (P1624) and it cleared as soon as I started the car after doing the mod. That code has came and gone and I think it was related to my HIDs as it came on and off ever since I installed them, but it could be this, or just a coincidence

wait what? Use some common sense and choose whether or not to believe a member who thinks his car threw a CEL because of HIDs... btw, P1624 is coolant temperature below thermostat regulating temperature

[phathom]

http://forum.e46fanatics.com/showthread.php?t=38959&highlight=maf+screens

Read up buddy. 17 pages. Starts out the same way as you and then progresses to people with broken MAFs and no performance gains. Even VERY reputable sponsors and tuners such as Active Autowerks and UUC advise members not to take out the screen.

EDIT: Went back and read your original post, and noticed that you added a little fine print. Lets see what it says...

wait what? Use some common sense and choose whether or not to believe a member who thinks his car threw a CEL because of HIDs... btw, P1624 is coolant temperature below thermostat regulating temperature

First time I've heard P1624 as that. When the code was read it read as auxilary input, auxilary output failure. When I searched it came up as
"Pedal Position Sensor Potentiometer Supply Channel 1 Electrical" And every post I've read on 1624 is about the pedal position sensor not coolant temp sensor. Modifying the electrical system can cause different drains and/or resistances on other parts of the car and may cause codes to be thrown. I had a friend install a HID kit and started getting the exact same code as well, this is what led me to believe that the HIDs caused it, because I never got it before, started getting it right after, and he had the exact same experience.

[neil1138]

First time I've heard P1624 as that. When the code was read it read as auxilary input, auxilary output failure. When I searched it came up as
"Pedal Position Sensor Potentiometer Supply Channel 1 Electrical" And every post I've read on 1624 is about the pedal position sensor not coolant temp sensor. Modifying the electrical system can cause different drains and/or resistances on other parts of the car and may cause codes to be thrown. I had a friend install a HID kit and started getting the exact same code as well, this is what led me to believe that the HIDs caused it, because I never got it before, started getting it right after, and he had the exact same experience.

looked it up on E46Fantics as well as the bentley manual. Look in the bentley manual buddy. here's exactly what it says "Pedal Position sensor Potentiometer Supply Channel 1 Electrical (M52: Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature))

I dont know if you know this but YOUR CAR, a 323 with an M52, does NOT have a pedal position sensor. I am pretty sure that part of the code is for M54 cars with electronic throttle....

[creeves328]

Creeves...so you're saying that the MAF could possibly read an erroneous increase in flow due to the differences in velocity? If the MAF read high, wouldn't that cause a slight "rich" condition, as opposed to "lean?" Just wanting to understand... Correct. The MAF will read higher without the screens, meaning your DME will enrichen the mixture. This isn't necessarily a bad thing, it all depends on how lean or rich you run before removing screens.

All - Regardless of what kind of make/model car you have, screen removal is done throughout the car enthusiast world. It could help, it could hurt.

[Matt]

DIY Low-accuracy MAF mod.

[creeves328]

I have a bone stock '93 325i...well, except for the K&N panel filter. Would you expect an improvement given the car's "stockness?"

You should put the stock filter back in. The K&N panel flows more CFM per sq. inch because of material, but the stock paper filter has more surface area. In total CFM per filter, the paper will win.

For your car being stock, the MAF mod isn't the first place to start.


Neil -- I agree its best to not remove the screens for most folks, some will find benefits. Its also not the first thing to do as a "mod". Checked the e46 thread, its cluttered with bad info; perspective without measured data, opinions without science.

[neil1138]

You should put the stock filter back in. The K&N panel flows more CFM per sq. inch because of material, but the stock paper filter has more surface area. In total CFM per filter, the paper will win.

For your car being stock, the MAF mod isn't the first place to start.


Neil -- I agree its best to not remove the screens for most folks, some will find benefits. Its also not the first thing to do as a "mod". Checked the e46 thread, its cluttered with bad info; perspective without measured data, opinions without science.

I agree also sir. It's just my duty to inform people that are considering this "mod." I would rather be bashed by the OP, than other members attempt this and possibly screw up their MAF/cars down the line. It's better to be informed.

I'm just speaking from what I've read and my knowledge of E46s which i think is fairly advanced from what I've done. MAFs are very sensitive and the general consensus among members of E46, is to NOT do this mod. It's not worth the risk for the minimal if any gain in HP/Torque

[bishop1977]

why not just polish and clean the throttle body, that has always been proven to restore lost power...taking out that mesh will cause more issues if the car can't correct for the extra airflow within its parameters...go full 90 and go into neutral and see what happens

[phathom]

go full 90 and go into neutral and see what happens

huh? explain.

[Wolfen]

So how much adjustability in fuel mixture does the stock ECU have in our cars? It is possible that this mod will show higher air flow into the intake. This information will in turn travel to the Computer and it will compensate to keep the mixture within certain parameters anyway. So you can conceivably make more power and all should be well. providing the new MAF readings are within the Computers range of ability in adjusting mixture settings.

One problem with the screens is that like mentioned here, alot of car models do not have them and run just fine. So clearly the principles of starightnening out air waves and pressure waves for a more uniform reading is valid. But how much is it valid and how much does it matter in practice? Ragardless of how you point the air over the seonsor to trick it's reading, a cartain ammount of air volume is going in regardless, the question is, is an open sensor with no screens perhaps even more accurate?

I tend to lean toward it possibly being able to give the sensor a more true reading of the incoming volume.

[bishop1977]

go 90 mph then put the car in neutral and coast see if the car reacts by turning off

[phathom]

go 90 mph then put the car in neutral and coast see if the car reacts by turning off
ummmm, no:confused

[bishop1977]

thats the only way to see if the turbulence you caused by hollowing it out will cause your car to go to sh1t

[phathom]

thats the only way to see if the turbulence you caused by hollowing it out will cause your car to go to sh1t
Well with that being close to double the speed limit here, I'm not going to do that. However I did do it at 70 and it was absolutely fine, popped it in neutral and it just dropped down to idle and sat there nice and smooth.

[daves330i]

The MAF screen was an old trick used on 5.0 mustangs back in the day, many articles have done the "mustang 10 minute tune up" which used to be a bump in timing, K/N filter and MAF screen and removing the air intake silencer.....it was later realized that it was better to leave it in as it "straightend" the airflow to make the sensor more accurate...I think with it out it was like 1hp or less....that whole thing was changed and people said it was better to just leave it. for so small a gain I would not risk a high dollar part....just not worth the time money if it goes bad or effort.

[bishop1977]

just clean your maf and throttle body and be done with it

[drewjohn]

had my car ONE day did this. result: Broken MAF sensor. Luckly dealer replaced part free of charge. DO NOT DO THIS!!! VERY EXPENSIVE TO FIX!!!

[phathom]

Warning to people considering this mod: Don't be an idiot and break your MAF sensor doing it. The MAF sensor isn't being broken from the mod, it's being broken when the modder accidently hits the MAF sensor while removing the screens and breaking the MAF sensor.

BTW: Don't put gas in your car either, it could spill and ruin the paint, it could also become ignited and blow your car up.

User error, don't do it.

[VanNuys303]

I read this thread a while back, and saw both sides of the idea.

I DID the mod on my stock (Other than an after market cone filter) 2002 325ci.
I did notice a gain in higher rpm pulls.

A problem thats been noted with a damaged MAF sensor is cruise control not working. Mine still works and i have had the screens out for like a month.

No weird idling problems at all. I MIGHT be getting worse fuel mileage but i'm not positive yet. I really don't care about that anyways. If i wanted good fuel mileage i would have bought a civic.


So, i'm with phantom. Thanks for the mod.

[phathom]

Thanks VanNuys. I have had this mod done to my car for 1 1/2 months now and have had no problems with the car at all. I have also drove it over 2000 miles in this time and subjected it to every test anyone here could want aside from the dyno which in this economy with my wife out of work I don't have a spare $100 to go do a couple pulls for shits and giggles. But mileage is unaffected, throttle response went up a little bit. It works great cold and hot, cruise control still works. No problems idling. Nothing.

This mod doesn't give you ridiculous gains, I'm not even sure on actual HP/TQ gains, but it does increase throttle response and makes the car a little more fun to drive.

[factory1o1]

my old mazda protege had a tear in the screen and it wouldnt idle for sh** even after cleaning it. replaced it and everything was good to go. every car reacts different i guess. my question though, do those screen pop on and off or do u have to break them off phantom? i would think removeing just the rear one shouldnt affect the sensors ability to read since the air has already passed the actual sensor part of the housing.


go 90 mph then put the car in neutral and coast see if the car reacts by turning off

that sounds dangerous, doesnt the car loose the power steering and brakes?

[neil1138]

that sounds dangerous, doesnt the car loose the power steering and brakes?

Think about this... "cars lose power steering and brakes if you put the car in neutral"??? News to me...

[phathom]

my old mazda protege had a tear in the screen and it wouldnt idle for sh** even after cleaning it. replaced it and everything was good to go. every car reacts different i guess. my question though, do those screen pop on and off or do u have to break them off phantom? i would think removeing just the rear one shouldnt affect the sensors ability to read since the air has already passed the actual sensor part of the housing.
Ya I have seen other cars that react weird to mafs being altered, but for these engines (M52Btu) it works fine. For the screens, they just pop in, pop out, takes a little force but they are removable and nothing breaks when taking them out.


that sounds dangerous, doesnt the car loose the power steering and brakes?
No, it doesn't lose that, only if the car is off, just putting it in neutral would mean the engine is on and at idle and the transmission is just in neutral and the car is coasting. You still have all your power stuff as the engine is on, just not driving the transmission.
Also as said I did that test at 70mph and it just sat at idle nice and smooth like it should.

[mkodama]

I took the MAF and air filter off, even less restriction than the DIY Hiflow MAF Mod! I know I haven't done a dyno yet, but I can tell you guys that I gained at least 20hp! You guys must do this and don't worry about any engine damage, BMW engines will be fine with this mod. Thanks so much for the inspiration phathom!

















Then I woke up and realized that removing stuff to protect your engine and sensors from harm, saying I had power gains without any physical proof, and telling other people to do the same and risk their engines was stupid.

[neil1138]

^ werd. Miles and I have said it from the beginning, to everyone who reads this thread, DONT do this mod.

[phathom]

^ werd. Miles and I have said it from the beginning, to everyone who reads this thread, DONT do this mod.
Prove me wrong (can't cuz you haven't driven my car before or after) or toss up some cash to have it dyno'd, otherwise STFU GTFO and DIAF

BTW: For the record, it's 3 months to the date as of tomorrow, I have put over 4,000 miles on it after the mod and have had absolutely zero problems whatsoever, gas mileage is the same, throttle response is slightly improved from stock, no hesitation, no idling problems, no anything.