MAF Descreening
Thread Starter
Racer
Joined: Sep 2000
Posts: 324
Likes: 0
From: Knoxville, Tennessee
MAF Descreening
Okay, I am posting this not to create an argument just to state what I know to be true. I have a 2005 vert that we put a halltech stinger on and kooks headers with high flow cats. After doing the install Bob Moss at Dragons Breath did a tune. He set the fuel trim curves at -2 to -3% , as well as his other magic...the car ran very well. When he did the install he asked if I wanted to descreen the MAF. I told him to leave it and we would do a before and after giving a month or two in between. I removed the MAF screen one weekend and drove it for a week or two, fuel mileage fell off and there was NO noticeable gains or losses in performance. Went back to see Bob at Dragons Breath to scan it and found that by removing the MAF screen the fuel trims went from -2 to -3% to 9 to 10%, this was from ONLY removing the screen...Bob then re-tuned to compesate for this...... What does this tell us? That YES, removing the screen significantly improves flow and after re-tuning for the removal, YES, you can sure as heck notice the improvement. So the answer to this question is? Leave the screen if you don't have a good tuner but if you DO tune for its removal it is certainly noticeable.
I am NOT here to argue...flamers go home...
I am NOT here to argue...flamers go home...
Last edited by evelkevin; Sep 20, 2006 at 11:02 AM.
Race Director
Joined: Feb 2006
Posts: 11,733
Likes: 15
From: SC
Dyno results pre descreen and post descreen? Could be just that the MAF was no longer getting an accurate reading on airflow, thus changing the fueling. The screen is to straighten the airflow and provide accuracy for the sensor, removing it will certainly throw it off.
Thread Starter
Racer
Joined: Sep 2000
Posts: 324
Likes: 0
From: Knoxville, Tennessee
Originally Posted by Silver05GTO
Dyno results pre descreen and post descreen? Could be just that the MAF was no longer getting an accurate reading on airflow, thus changing the fueling. The screen is to straighten the airflow and provide accuracy for the sensor, removing it will certainly throw it off.
Last edited by evelkevin; Sep 20, 2006 at 11:40 AM.
Melting Slicks
Joined: Jun 2006
Posts: 2,208
Likes: 1
Originally Posted by Silver05GTO
Dyno results pre descreen and post descreen? Could be just that the MAF was no longer getting an accurate reading on airflow, thus changing the fueling. The screen is to straighten the airflow and provide accuracy for the sensor, removing it will certainly throw it off.
That's why I never considered doing it to my Trans Ams and won't to the C6. While it may in fact increase volume of air, there are other variables to consider--and I am far from an expert on downstream risk. 
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
LTFT's measure the amount of air comming in and in this case it increased the amount, it didnt disrupt it. It is 11% leaner at closed loop. Since it went 9% positive the computer will only add 9% to the open loop fueling. More air and fuel = more power. I will be doing this to my car since I have 2 descreened MAF's available as an A/B comparison. I will report back the findings.
I think your findings are more valid than a dyno. To each his own. Thanks for taking the time to share this info. For the nay-sayers, speed density guys have shown a close to 20hp increase by removing the MAF altogether.
I think your findings are more valid than a dyno. To each his own. Thanks for taking the time to share this info. For the nay-sayers, speed density guys have shown a close to 20hp increase by removing the MAF altogether.
Le Mans Master
Joined: Sep 2004
Posts: 7,027
Likes: 6
From: Shiloh Ohio
Originally Posted by SpinMonster
LTFT's measure the amount of air comming in and in this case it increased the amount, it didnt disrupt it. It is 11% leaner at closed loop. Since it went 9% positive the computer will only add 9% to the open loop fueling. More air and fuel = more power. I will be doing this to my car since I have 2 descreened MAF's available as an A/B comparison. I will report back the findings.
I think your findings are more valid than a dyno. To each his own. Thanks for taking the time to share this info. For the nay-sayers, speed density guys have shown a close to 20hp increase by removing the MAF altogether.
I think your findings are more valid than a dyno. To each his own. Thanks for taking the time to share this info. For the nay-sayers, speed density guys have shown a close to 20hp increase by removing the MAF altogether.
Team Owner
Joined: Feb 2001
Posts: 27,254
Likes: 136
From: Short Hills, NJ
I have always been a fan of MAF screen removal, going on 4+ years now (2 untuned, almost 2 with tuning) in my Z28 with no screen and no problems but I'm just not sure I want to do it on my C6 yet.
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Thread Starter
Racer
Joined: Sep 2000
Posts: 324
Likes: 0
From: Knoxville, Tennessee
Originally Posted by SpinMonster
LTFT's measure the amount of air comming in and in this case it increased the amount, it didnt disrupt it. It is 11% leaner at closed loop. Since it went 9% positive the computer will only add 9% to the open loop fueling. More air and fuel = more power. I will be doing this to my car since I have 2 descreened MAF's available as an A/B comparison. I will report back the findings.
I think your findings are more valid than a dyno. To each his own. Thanks for taking the time to share this info. For the nay-sayers, speed density guys have shown a close to 20hp increase by removing the MAF altogether.
I think your findings are more valid than a dyno. To each his own. Thanks for taking the time to share this info. For the nay-sayers, speed density guys have shown a close to 20hp increase by removing the MAF altogether.
As a matter of fact Bob switched his "Violater" tuning to speed density as his modifications far exceeded the capacity of a MAF.
Safety Car
Joined: Dec 2004
Posts: 3,565
Likes: 5
From: stafford country, va. Avatar: Me on turn 3 @ Bristol (The World's Fastest Half-Mile)
Originally Posted by SpinMonster
LTFT's measure the amount of air comming in and in this case it increased the amount, it didnt disrupt it. It is 11% leaner at closed loop. Since it went 9% positive the computer will only add 9% to the open loop fueling. More air and fuel = more power. I will be doing this to my car since I have 2 descreened MAF's available as an A/B comparison. I will report back the findings.
I think your findings are more valid than a dyno. To each his own. Thanks for taking the time to share this info. For the nay-sayers, speed density guys have shown a close to 20hp increase by removing the MAF altogether.
I think your findings are more valid than a dyno. To each his own. Thanks for taking the time to share this info. For the nay-sayers, speed density guys have shown a close to 20hp increase by removing the MAF altogether.
Race Director
Joined: Mar 2005
Posts: 11,549
Likes: 27
From: Southampton NJ
Originally Posted by Zig
i would be interested in knowing if rotating the maf 90 degrees after descreening changes/helps airflow. i've been running this way for awhile but i don't have anything to measure it with. i've also removed the back half of the built-in air diffusor, inside the maf, and have polished the front, but i wouldn't suspect you would want to get into that.....
Race Director
Joined: Aug 2005
Posts: 13,592
Likes: 187
From: Hudson WI
NCM Sinkhole Donor
I deal with the car companies as my daily job and I don't beleive that they would spend the money for the screen if it didn't do something to improve performance, emissons or fuel economy.
Le Mans Master
Joined: Jun 2004
Posts: 6,269
Likes: 50
From: Dallas Texas
St. Jude Donor '06-'07-'09-'10
I suspect that the only reason that screen is there is to keep big stuff from going in the engine when some yoyo decides to run without the filter. 
As has been said, if it's so important, how come the Z06 doesn't use it?
As has been said, if it's so important, how come the Z06 doesn't use it?
Safety Car
Joined: Dec 2004
Posts: 3,565
Likes: 5
From: stafford country, va. Avatar: Me on turn 3 @ Bristol (The World's Fastest Half-Mile)
Originally Posted by dennis50nj
Rob glad your back ...
thanks, looks like the 'wife' was right. just kinda needed to take a brake for a bit.
Drifting
Joined: Jul 2005
Posts: 1,533
Likes: 0
From: az
the change in ltft could be more air is coming through or the maf is not able to meter air correctly now, which requires your ecm to make adjustments. we will never know for sure now since your car has been retune.
Le Mans Master
Joined: Feb 2006
Posts: 5,762
Likes: 4
From: Chandler Arizona
I have always thought that the screen was a flow straightener in order to make the MAF more accurate. But then GM went and descreened the MAF on the C5 Z06, so heck, it must be OK.
Last edited by glennhl; Sep 21, 2006 at 01:29 AM.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Originally Posted by timd38
I deal with the car companies as my daily job and I don't beleive that they would spend the money for the screen if it didn't do something to improve performance, emissons or fuel economy.
The 2002-2004 Z06 has the exact same MAF as the 2001 and they deleted the screen. So what was it then, the engineers changed their minds again? I have 2 in the boxes they came in. Same number, same size, no screen.
You oppose every mod
