Mass air flow sensor
Melting Slicks
Joined: Sep 2006
Posts: 2,034
Likes: 0
From: Beaverton OR
Yes, two weeks ago. Had problems with hard shifting with my A4, check engine light and traction control warning. I figured something was wrong with the tranny and took it to the dealer.
No transmission problems, and computer indicated a problem with the MAF. Replaced the MAF and all problems went away.
Go figure.....
No transmission problems, and computer indicated a problem with the MAF. Replaced the MAF and all problems went away.
Go figure.....
Team Owner
Joined: Mar 2006
Posts: 50,968
Likes: 0
From: Jurassic Park Socal.
St. Jude Donor '08-'09-'10-'11
From what Ive been told by some performance vendors those after market MAF sensors dont do a whole lot cept shrink your wallet or make the car throw codes but what do I know.
Pro
Joined: Mar 2007
Posts: 585
Likes: 0
From: Coral Springs Florida
Maf
Has anybody removed the MAF Screen from their LS2? If so any issues? I've read it can sometimes benefit or hurt your motor's performance. I know the LS6s came with de-screened MAF. I want to remove mine for more airflow to compliment my VR Throttle body and Varam Intake.
Any insight would be appreciated-Thanks
Any insight would be appreciated-Thanks
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Le Mans Master
Joined: Jan 2003
Posts: 8,596
Likes: 19
From: Portland Oregon
Aftermarket MAFs are nothing but a marketing landslide for the guy selling them. They do nothing for performance gains and sometimes can be detrimental to performance. Case in point, just the other day during a dyno tunin session on a 6 liter LQ9 LS1 truck, the fuel trims were skewed positive 20%+ and setting a lean code. I had a stock truck MAF as a test unit and installing that all but cleared the fuel trim issue. This was a extreme case but it isn't that uncommon. I ended up rescaling his MAF tables within the PCM to cure the problem. The only decent aftermarket MAF that really does something is the LPE 4 inch meter that has tables supplied so that one can program their PCM accordingly. If you want a sensor that will handle all the HP that your engine could possibly make, this sensor is for you.
Another point about descreening the sensors, IMHO I would never recommend doing so. The screens are not debris screens, they are actually straighten vanes. The MAF sensor is a precision flow measurement device, the screen makes for a more laminar flow to reduce any turbulance that may be encountered in the piping to the sensor. Any turbulance can cause erratic signals and improper fueling. I know many have descreened them in the past and not had a problem but to those that have did you check the fuel trims after the desceening to see if they are skewed on way or not. The fuel trims could be skewed by a considerable amount and not set a rich or a lean bank code. So you would never know if you had a problem or not.
Case in point the other day while tuning another truck with a aftermarket air intake encountered air flow anomolies past 5600 RPM. I would see the fuel go very rich after that point, datalogging via a GM TECH2 shows that air flow readings after 5600 varied by as much as 100 to 150 g/sec, using a lab scope showed the same strange anomoly in a recorded scope trace. Rescaling the MAF table in that area to "flatline" the curve cured the issue, any fueling needs was adjusted in the PE tables to adjust WOT AFR.
A little note about flow elements, generally in the process situations, as a standard most primary flow elements such as a MASS flow device they need X upstream lengths of pipe and down stream lengths of pipe, usually this is expressed in pipe diameters. For example a mag flow meter in a 6" pipe line would require 5 pipe diameters up stream or 30 inches and 3 diameters or 15" down stream, an installation standard such as this reduces flow turbulance and reduces signal noise. Speaking of signal noise, in the process industry with their complex process control systems we can often tune out noise with dampening and filtering programming, unfortunately we don't have that luxuary in the PCM programming, and even if we did filtering and or dampening would slow the signal response down and therefore we could risk a lean out condition or an overly rich condition.
Another point about descreening the sensors, IMHO I would never recommend doing so. The screens are not debris screens, they are actually straighten vanes. The MAF sensor is a precision flow measurement device, the screen makes for a more laminar flow to reduce any turbulance that may be encountered in the piping to the sensor. Any turbulance can cause erratic signals and improper fueling. I know many have descreened them in the past and not had a problem but to those that have did you check the fuel trims after the desceening to see if they are skewed on way or not. The fuel trims could be skewed by a considerable amount and not set a rich or a lean bank code. So you would never know if you had a problem or not.
Case in point the other day while tuning another truck with a aftermarket air intake encountered air flow anomolies past 5600 RPM. I would see the fuel go very rich after that point, datalogging via a GM TECH2 shows that air flow readings after 5600 varied by as much as 100 to 150 g/sec, using a lab scope showed the same strange anomoly in a recorded scope trace. Rescaling the MAF table in that area to "flatline" the curve cured the issue, any fueling needs was adjusted in the PE tables to adjust WOT AFR.
A little note about flow elements, generally in the process situations, as a standard most primary flow elements such as a MASS flow device they need X upstream lengths of pipe and down stream lengths of pipe, usually this is expressed in pipe diameters. For example a mag flow meter in a 6" pipe line would require 5 pipe diameters up stream or 30 inches and 3 diameters or 15" down stream, an installation standard such as this reduces flow turbulance and reduces signal noise. Speaking of signal noise, in the process industry with their complex process control systems we can often tune out noise with dampening and filtering programming, unfortunately we don't have that luxuary in the PCM programming, and even if we did filtering and or dampening would slow the signal response down and therefore we could risk a lean out condition or an overly rich condition.
Last edited by tjwong; Mar 22, 2007 at 12:32 AM.
Pro
Joined: Mar 2007
Posts: 585
Likes: 0
From: Coral Springs Florida
Aftermarket MAFs are nothing but a marketing landslide for the guy selling them. They do nothing for performance gains and sometimes can be detrimental to performance. Case in point, just the other day during a dyno tunin session on a 6 liter LQ9 LS1 truck, the fuel trims were skewed positive 20%+ and setting a lean code. I had a stock truck MAF as a test unit and installing that all but cleared the fuel trim issue. This was a extreme case but it isn't that uncommon. I ended up rescaling his MAF tables within the PCM to cure the problem. The only decent aftermarket MAF that really does something is the LPE 4 inch meter that has tables supplied so that one can program their PCM accordingly. If you want a sensor that will handle all the HP that your engine could possibly make, this sensor is for you.
Another point about descreening the sensors, IMHO I would never recommend doing so. The screens are not debris screens, they are actually straighten vanes. The MAF sensor is a precision flow measurement device, the screen makes for a more laminar flow to reduce any turbulance that may be encountered in the piping to the sensor. Any turbulance can cause erratic signals and improper fueling. I know many have descreened them in the past and not had a problem but to those that have did you check the fuel trims after the desceening to see if they are skewed on way or not. The fuel trims could be skewed by a considerable amount and not set a rich or a lean bank code. So you would never know if you had a problem or not.
Case in point the other day while tuning another truck with a aftermarket air intake encountered air flow anomolies past 5600 RPM. I would see the fuel go very rich after that point, datalogging via a GM TECH2 shows that air flow readings after 5600 varied by as much as 100 to 150 g/sec, using a lab scope showed the same strange anomoly in a recorded scope trace. Rescaling the MAF table in that area to "flatline" the curve cured the issue, any fueling needs was adjusted in the PE tables to adjust WOT AFR.
A little note about flow elements, generally in the process situations, as a standard most primary flow elements such as a MASS flow device they need X upstream lengths of pipe and down stream lengths of pipe, usually this is expressed in pipe diameters. For example a mag flow meter in a 6" pipe line would require 5 pipe diameters up stream or 30 inches and 3 diameters or 15" down stream, an installation standard such as this reduces flow turbulance and reduces signal noise. Speaking of signal noise, in the process industry with their complex process control systems we can often tune out noise with dampening and filtering programming, unfortunately we don't have that luxuary in the PCM programming, and even if we did filtering and or dampening would slow the signal response down and therefore we could risk a lean out condition or an overly rich condition.
Another point about descreening the sensors, IMHO I would never recommend doing so. The screens are not debris screens, they are actually straighten vanes. The MAF sensor is a precision flow measurement device, the screen makes for a more laminar flow to reduce any turbulance that may be encountered in the piping to the sensor. Any turbulance can cause erratic signals and improper fueling. I know many have descreened them in the past and not had a problem but to those that have did you check the fuel trims after the desceening to see if they are skewed on way or not. The fuel trims could be skewed by a considerable amount and not set a rich or a lean bank code. So you would never know if you had a problem or not.
Case in point the other day while tuning another truck with a aftermarket air intake encountered air flow anomolies past 5600 RPM. I would see the fuel go very rich after that point, datalogging via a GM TECH2 shows that air flow readings after 5600 varied by as much as 100 to 150 g/sec, using a lab scope showed the same strange anomoly in a recorded scope trace. Rescaling the MAF table in that area to "flatline" the curve cured the issue, any fueling needs was adjusted in the PE tables to adjust WOT AFR.
A little note about flow elements, generally in the process situations, as a standard most primary flow elements such as a MASS flow device they need X upstream lengths of pipe and down stream lengths of pipe, usually this is expressed in pipe diameters. For example a mag flow meter in a 6" pipe line would require 5 pipe diameters up stream or 30 inches and 3 diameters or 15" down stream, an installation standard such as this reduces flow turbulance and reduces signal noise. Speaking of signal noise, in the process industry with their complex process control systems we can often tune out noise with dampening and filtering programming, unfortunately we don't have that luxuary in the PCM programming, and even if we did filtering and or dampening would slow the signal response down and therefore we could risk a lean out condition or an overly rich condition.
This guy sounds like he knows his SH*T! I'm not de-screening -Thanks Bro!
Race Director
Joined: Aug 2005
Posts: 13,592
Likes: 187
From: Hudson WI
NCM Sinkhole Donor
I happen to agree, but this thread will go on for days with people that support both sides with data. I believe that GM would save the $0.12 or so if they could get by not having it if it wasn't needed. Those on the other side will say that the LS6 didn't have one, so why does the LS2 need it....
Instructor
Joined: Jan 2003
Posts: 226
Likes: 0
From: debary fl
Has anybody removed the MAF Screen from their LS2? If so any issues? I've read it can sometimes benefit or hurt your motor's performance. I know the LS6s came with de-screened MAF. I want to remove mine for more airflow to compliment my VR Throttle body and Varam Intake.
Any insight would be appreciated-Thanks
Any insight would be appreciated-Thanks
Why try to add more air and have just about a 3rd of the mass air flow blocked? Squash one flat from edge to edge and see why
Melting Slicks
Joined: Jun 2006
Posts: 2,690
Likes: 1
From: Northern Calif
I have read that those of us with reusable air filter (read oiled) can foul the MAF with oil residue that will cause tranny probs ect... Believe it or not that thing can influence our tranny. Proof see OCCOM's post) So when I oil my filter and thing go haywire, I'll keep this in the back of my mind.
Drifting
Joined: Feb 2007
Posts: 1,446
Likes: 0
From: Cranford NJ
