: Anyone descreen their mafs?



AlmostAV
04-04-08, 02:28 AM
Just wondering if anyone has descreened their mafs (mass air flow sensor) Thanks

JonCR96Z
04-04-08, 02:34 AM
yeah

ewill3rd
04-04-08, 08:23 AM
Lots of people have, mostly the ones that wish they had never done it.
The "screen" is there for a reason.

NormV
04-04-08, 08:37 AM
One word, don't. Especially if you plan on getting a tune down the road. The screen evens out the airflow and so much easier to tune. Ask me how I know. Might even save your motor. :)

Norm

BBD
04-04-08, 10:48 AM
Quick question; is the screen only on the LS6? I have the 06' and when I was cleaning the air filter on my truck I took both sensors out to clean them as well (with the proper spray cleaner, did not touch the elements) I noticed my truck's had the screen but not the V. I have not messed with it so I assume it came that way. I have heard you guys talk about it before but never thought much about it before.

jr_vette
04-04-08, 11:35 AM
Quick question; is the screen only on the LS6? I have the 06' and when I was cleaning the air filter on my truck I took both sensors out to clean them as well (with the proper spray cleaner, did not touch the elements) I noticed my truck's had the screen but not the V. I have not messed with it so I assume it came that way. I have heard you guys talk about it before but never thought much about it before.

Both?

Also, are you guys sure the LS6 has a screen? The 02-04 Z06's don't have one from the factory. I haven't looked at my LS2 V yet. Also, FWIW, I put a screenless Z06 MAF in my C5. After a tune, it worked fine. I would be willing to bet the only reason I got more HP, was because it was larger than my stock (99) MAF.

Personally I think removing the screen is a waste of time and not worth the effort. Go throw a sticker on the car instead.

CTSV_Rob
04-04-08, 12:57 PM
I don't remember seeing a screen in the 07 LS2 MAF.

Dirk Diggler
04-04-08, 02:17 PM
Only descreen it if you are going to get it tuned afterwards. If not leave it alone

BBD
04-04-08, 02:52 PM
Both?

Also, are you guys sure the LS6 has a screen? The 02-04 Z06's don't have one from the factory. I haven't looked at my LS2 V yet. Also, FWIW, I put a screenless Z06 MAF in my C5. After a tune, it worked fine. I would be willing to bet the only reason I got more HP, was because it was larger than my stock (99) MAF.

Personally I think removing the screen is a waste of time and not worth the effort. Go throw a sticker on the car instead.

I was talking about from the truck and car....one each comparing them, that is when I noticed one had a screen and the other did not.

The Tony Show
04-04-08, 02:59 PM
The 'vettes don't have them because the air goes straight into the Throttle Body. Since the V has a 90deg elbow before the TB, the screen helps straighten the airflow to make that turn. Leave it there.

AlmostAV
04-04-08, 03:19 PM
But the ls2 V's do not have them? Dont they use the same intake tube?

The Tony Show
04-04-08, 03:32 PM
Similar, but not exactly. I don't claim to be an engineer, but there's plenty of people who have descreened their LS6 MAF and had the car run shitty as a result. I can't debate the "why" and "how", all I'm going on is other people's experience.

Dirk Diggler
04-04-08, 04:16 PM
Similar, but not exactly. I don't claim to be an engineer, but there's plenty of people who have descreened their LS6 MAF and had the car run shitty as a result. I can't debate the "why" and "how", all I'm going on is other people's experience.

Most who have done this neglected to get the car retuned after doing so that is why they ran shitty. It changes the flow characteristics enough to affect fueling of the vehicle. A retune is on order after descreening of the maf.

Naf
04-04-08, 04:44 PM
The LS2 has a new style Maf with new FQ table then our LS6 Mafs.

I am going to swap out mine for a 100mm once i get my new Rad...LPE all The way

NormV
04-04-08, 05:02 PM
Even trying to tune you'll be chasing your tail with no screen as with the 90 elbow creates turbulence that confuses the maf. The Vettes, as JR mentions, can get away with this as it is a relatively straight shot from the filter through the maf. Unless you have over the radiator intake like Jon, keep the screen.

If the air flow over the maf is not laminar the readings will create inconsisent fuel as it tries to match the flucuating air flow.

The maf and map are blending under certain situations. The map is more of a fail safe if the maf fails. But the maf does see what is coming into the engine before the map will and helps with tranisition throttle.


Norm


Most who have done this neglected to get the car retuned after doing so that is why they ran shitty. It changes the flow characteristics enough to affect fueling of the vehicle. A retune is on order after descreening of the maf.

CTSV_Rob
04-04-08, 05:54 PM
Well if the screen is required and a tune will not fix it then why don't I have one? I would tend to believe you Norm but I have proof against your theory.

Bottom line is people have tried after market MAF's and had little to no success with getting additional power (from what I have read). I'm guessing the factory MAF is pretty efficent and the flow restrictions are elsewhere.

Naf,

If that After Market works for you I would like to see the results and to know how your intake is put together.

benelliwang
04-04-08, 06:54 PM
LS1 Corvettes, even with a straight shot, has a screened MAF.
LS1 Fbodies has a screened MAF.
My LS6 Caddie has a screened MAF.
LS6 Corvettes has a screened MAF.
LS2 Corvettes & Caddies, I have no idea and it seems that there is no screen. Could there be a screen at the beginning of the air box tube? Or maybe the LS2 MAF's so much better and does not require a screen to keep it accurate?

I know this much about LS1/6 MAF's:
1. 4 years ago I logged my Vette on Autotap with and without MAF. It had on heads/cam/full bolt-on/N2O, and the descreen MAF was a mess down low, all over the place. Putting a screened MAF back on gain cleaned out the flow. But do keep in mind that this is with a cam.

2. If you oil too much with your K&N filter will mess up the MAF, dont' use too much and clean often. My friend's turbo car started having issues when the MAF got coated with K&N filter oil. Cleaning the MAF fixed the problem. Use less oil on the filter.

3. When I tuned my car's VE table using Speed Density and MAF unplugged, it actually ran better and I was able to get -1% on all LTFT cells. Once I plugged the MAF back in and try to dial in the MAF, the LTFT would never be as perfect as in Speed Density mode, no matter how many times I log and tune. I can get it to pretty good (0 to -5% on cells) but not perfect. That is why my Vette is now speed density only with 2 Bar Map sensor.

Pretty soon, when I have more time to tune, I will turn the Caddie in to speed density too.

NormV
04-04-08, 07:13 PM
Rob, not sure but if you look at the two engine differences I do know that the LS2 has bigger throttle body which might create less distrubance. Not sure about the Maf difference. My 05 GTO had a screen. Weird!

Ben, your long term fuel trims are just an average of the short term trims. So you should be able to get them close to perfect. I usually zero out the maf, dfco off, and tune under 4,000 rpms to stay out of power enrichment mode to tune VE. Then enable maf and tune it.

Norm

benelliwang
04-04-08, 08:32 PM
Ben, your long term fuel trims are just an average of the short term trims. So you should be able to get them close to perfect. I usually zero out the maf, dfco off, and tune under 4,000 rpms to stay out of power enrichment mode to tune VE. Then enable maf and tune it.

Norm
Yeap, already know that. I've started tuning back in 2001 when I bought LS1 Edit and AutoTap. I am now on HP Tuner with MPVI Pro EIO hooked to Wide Band O2. All I have to do is to zero the maf like you say, kill PE and dfco, hook up the wideband and log all the cells untill I get atleast 100 counts in each cell. Then get the adjustments into the tune, flash, and repeat.

Took me one night to get VE table tuned with speed density. But MAF with a wild cam is just a pain in the ass with a MAF. I have tried LS1 MAF, LS6 MAF, & aftermarket MAF, the LTFT & STFT looks good but just not as "great" as Speed Density (0 to -5% LTFT vs 0 to -1% LTFT).

Besides I am twin turbo now, the stupid MAF maxes out when I hit boost anyways, more airflow than it is designed to measure. Making tuning a guess between boost ranges, so I tossed the MAF.

On the Caddie, I got the VE done the same way in 2 hours. Hooked the MAF back up and it was a mess. Cleaned it, and it still wasn't right, keep in mind that it was reading within spec but I am annal. Took me awhile to adjust it back down correctly to have mostly 0 to -1% LTFT but some cells on the upper left protion continue to have -5% LTFT, which is well within the operating range and better then any stock ones I've logged in Vegas. But I am still gonna toss the MAF soon.

Back in 2002 when are we are still trying to tune with MAF and buying aftermarket MAFs, the Aussies are already throwing MAF away and tuning with Speed Density on cams US people swears that it is too wild for the streets. Yet it runs fine on the streets.

Sorry I am way off topic here lol.

NormV
04-04-08, 08:50 PM
Sounds like your right on target!

No, definietly on target as allot of dyno tuners tune in PE mode, collect their couple hundred bucks, and unstrap it from the dyno. A local shop dyno a friend of a friend's GTO. He later bought hptuners and found that the ve tables weren't touched. This was on a camed car is other intake and exhaust mods about 70 whp in total. D'oh!

Norm



Yeap, already know that. I've started tuning back in 2001 when I bought LS1 Edit and AutoTap. I am now on HP Tuner with MPVI Pro EIO hooked to Wide Band O2. All I have to do is to zero the maf like you say, kill PE and dfco, hook up the wideband and log all the cells untill I get atleast 100 counts in each cell. Then get the adjustments into the tune, flash, and repeat.

Took me one night to get VE table tuned with speed density. But MAF with a wild cam is just a pain in the ass with a MAF. I have tried LS1 MAF, LS6 MAF, & aftermarket MAF, the LTFT & STFT looks good but just not as "great" as Speed Density (0 to -5% LTFT vs 0 to -1% LTFT).

Besides I am twin turbo now, the stupid MAF maxes out when I hit boost anyways, more airflow than it is designed to measure. Making tuning a guess between boost ranges, so I tossed the MAF.

On the Caddie, I got the VE done the same way in 2 hours. Hooked the MAF back up and it was a mess. Cleaned it, and it still wasn't right, keep in mind that it was reading within spec but I am annal. Took me awhile to adjust it back down correctly to have mostly 0 to -1% LTFT but some cells on the upper left protion continue to have -5% LTFT, which is well within the operating range and better then any stock ones I've logged in Vegas. But I am still gonna toss the MAF soon.

Back in 2002 when are we are still trying to tune with MAF and buying aftermarket MAFs, the Aussies are already throwing MAF away and tuning with Speed Density on cams US people swears that it is too wild for the streets. Yet it runs fine on the streets.

Sorry I am way off topic here lol.

PISNUOFF
04-05-08, 12:17 AM
Even trying to tune you'll be chasing your tail with no screen as with the 90 elbow creates turbulence that confuses the maf. The Vettes, as JR mentions, can get away with this as it is a relatively straight shot from the filter through the maf. Unless you have over the radiator intake like Jon, keep the screen.

If the air flow over the maf is not laminar the readings will create inconsisent fuel as it tries to match the flucuating air flow.

The maf and map are blending under certain situations. The map is more of a fail safe if the maf fails. But the maf does see what is coming into the engine before the map will and helps with tranisition throttle.


Norm

Norm is exactly right. That is the purpose of the screens. Some designs have them incorporated into them and some don't. My '07 does not have a screen and is different all together from an '04-'05.

Removing the screen does increase the total flow of air. However, the laminar flow over the heating elements creates consistency and doesn't allow the turbulence to reduce the ratio of air across the heating elements to total flow. When this happens, the output of the MAF is reduced at any given actual flow rate causing a leaner engine operation condition resulting from the fuel calculations based on lower air flow than actual.

AlmostAV
04-05-08, 03:42 AM
z06 does not have a maf screen

Rey
04-05-08, 11:27 AM
When I bought my CTS-V I had some long discussions with TPIS owner and friend Myron Cottrell about the MAF screen. He always removes it, and has for many years. He has dynoed the change many times, and consistently sees a small hp gain. So, I did too and noticed no degredation of performance whatsoever on a TPIS-"tuned" CTS-V with headers and intake. Any performance gain was too small to register on my "seat-of pants" dyno. No doubt the screeen does "straighten" airflow, and perhaps it helps in some way. But if the airflow is "straight" to begin with like on a Corvette why bother?
When I engineered my 4 inch intake tube, I moved the MAF from its location next to the air filter to adjacent to the 90 degree bend into the intake. I had to make a small wire extension, but otherwise no worries with the installation. My thinking was I needed the room and why not straighten the airflow before the MAF. I figured it would not hurt. Again, there seemed to be measureable effect on driveability.
I wondered just how much the screen obstructs airflow, so I crushed the screen down to a solid mass which measured 0.75 sq. in. altogether.
The amusing thing about this discussion is that no matter what I write, there will be some who do not believe it and will hang on to their MAF screen. Others, who advocate screen removal have prsobably done this months ago.

NormV
04-05-08, 12:36 PM
I agree with the peak power as the air is flow very fast and results will come. But under most driving conditions with throttle transitions there will be turbulence and the screen makes it possible to tune this area otherwise your chasing your tail as the airflow is never consistent at rpms/gsec.

That is why when looking for peak power most will just remove the MAF.

Norm


When I bought my CTS-V I had some long discussions with TPIS owner and friend Myron Cottrell about the MAF screen. He always removes it, and has for many years. He has dynoed the change many times, and consistently sees a small hp gain. So, I did too and noticed no degredation of performance whatsoever on a TPIS-"tuned" CTS-V with headers and intake. Any performance gain was too small to register on my "seat-of pants" dyno. No doubt the screeen does "straighten" airflow, and perhaps it helps in some way. But if the airflow is "straight" to begin with like on a Corvette why bother?
When I engineered my 4 inch intake tube, I moved the MAF from its location next to the air filter to adjacent to the 90 degree bend into the intake. I had to make a small wire extension, but otherwise no worries with the installation. My thinking was I needed the room and why not straighten the airflow before the MAF. I figured it would not hurt. Again, there seemed to be measureable effect on driveability.
I wondered just how much the screen obstructs airflow, so I crushed the screen down to a solid mass which measured 0.75 sq. in. altogether.
The amusing thing about this discussion is that no matter what I write, there will be some who do not believe it and will hang on to their MAF screen. Others, who advocate screen removal have prsobably done this months ago.

benelliwang
04-06-08, 01:01 AM
I agree with the peak power as the air is flow very fast and results will come. But under most driving conditions with throttle transitions there will be turbulence and the screen makes it possible to tune this area otherwise your chasing your tail as the airflow is never consistent at rpms/gsec.

That is why when looking for peak power most will just remove the MAF.

Norm

Exactly. Norm and I are not saying it will not gain power when you descreen it, we are saying it is more inaccurate in other situations were your foot is not through the floor. Especially with a wilder cam.

JMBCTSV
04-07-08, 08:46 AM
LS2 corvette has a screen

jr_vette
04-17-08, 08:56 AM
LS1 Corvettes, even with a straight shot, has a screened MAF.
LS1 Fbodies has a screened MAF.
My LS6 Caddie has a screened MAF.
LS6 Corvettes has a screened MAF.
LS2 Corvettes & Caddies, I have no idea and it seems that there is no screen. Could there be a screen at the beginning of the air box tube? Or maybe the LS2 MAF's so much better and does not require a screen to keep it accurate?

I know this much about LS1/6 MAF's:
1. 4 years ago I logged my Vette on Autotap with and without MAF. It had on heads/cam/full bolt-on/N2O, and the descreen MAF was a mess down low, all over the place. Putting a screened MAF back on gain cleaned out the flow. But do keep in mind that this is with a cam.

2. If you oil too much with your K&N filter will mess up the MAF, dont' use too much and clean often. My friend's turbo car started having issues when the MAF got coated with K&N filter oil. Cleaning the MAF fixed the problem. Use less oil on the filter.

3. When I tuned my car's VE table using Speed Density and MAF unplugged, it actually ran better and I was able to get -1% on all LTFT cells. Once I plugged the MAF back in and try to dial in the MAF, the LTFT would never be as perfect as in Speed Density mode, no matter how many times I log and tune. I can get it to pretty good (0 to -5% on cells) but not perfect. That is why my Vette is now speed density only with 2 Bar Map sensor.

Pretty soon, when I have more time to tune, I will turn the Caddie in to speed density too.

Bolded = Wrong.