View Poll Results: Have you ever had a MAF sensor problem with these filters:
BMC
0
0%
K&N
5
83.33%
OEM (paper)
0
0%
Other
1
16.67%
Voters: 6. You may not vote on this poll
Ever had a MAF Problem with an Oiled Air Filter?
07-06-2018, 09:28 PM
#16
07-06-2018, 10:13 PM
#17
Rennlist Member
I'm certain that 991s are MAF-less. The 997.2 models where the last models to use these. The computers got good enough at calculated the air flow without the hot wire approach.
07-06-2018, 10:16 PM
#18
Rennlist Member
Found it on page 15 of the 991 Technics Manual:
"The intake system has been derestricted by omitting the hot-film mass air flow sensor in the intake tract and using a pressure sensor for load detection on the intake manifold instead."
Edit: Additionally on page 31, quoting:
"The intake system has been derestricted by omitting the hot-film mass air flow sensor in the intake tract and using a pressure sensor for load detection on the intake manifold instead."
Edit: Additionally on page 31, quoting:
Advantages of the pressure sensor for detecting the engine load:
• Increased power as a result of derestriction of the intake section
• Greater precision at low air-flow rates
• Enhanced resistance to soiling
• Increased power as a result of derestriction of the intake section
• Greater precision at low air-flow rates
• Enhanced resistance to soiling
07-06-2018, 10:27 PM
#19
Found it on page 15 of the 991 Technics Manual:
"The intake system has been derestricted by omitting the hot-film mass air flow sensor in the intake tract and using a pressure sensor for load detection on the intake manifold instead."
Edit: Additionally on page 31, quoting:
"The intake system has been derestricted by omitting the hot-film mass air flow sensor in the intake tract and using a pressure sensor for load detection on the intake manifold instead."
Edit: Additionally on page 31, quoting:
Advantages of the pressure sensor for detecting the engine load:
• Increased power as a result of derestriction of the intake section
• Greater precision at low air-flow rates
• Enhanced resistance to soiling
• Increased power as a result of derestriction of the intake section
• Greater precision at low air-flow rates
• Enhanced resistance to soiling
07-07-2018, 02:27 AM
#21
My 355 spent about half of 2016 on jackstands in my garage while I chased after the reason for my first failed CA smog in 16 yrs of ownership. Car failed ONLY on high NOx. After recoring cats (fabspeed)replacing O2 sensors and still failing to get it passed, it turned out to be MAF sensors that were fouled by a K & N that was installed @ my first major in 2003. Took many years, but yes a K & N will f up a ferrari MAF.
07-07-2018, 02:59 AM
#22
My 355 spent about half of 2016 on jackstands in my garage while I chased after the reason for my first failed CA smog in 16 yrs of ownership. Car failed ONLY on high NOx. After recoring cats (fabspeed)replacing O2 sensors and still failing to get it passed, it turned out to be MAF sensors that were fouled by a K & N that was installed @ my first major in 2003. Took many years, but yes a K & N will f up a ferrari MAF.
07-07-2018, 03:29 PM
#23
yep, zero cleaning. I had forgotten that the k & n was even in there bc I did not install it- a friend who was a pro F mechanic put it in during first major and just mentioned it w a million other things in a phone call. My bad, but I got a lot done & improved the car in many ways while chasing the prob.
07-08-2018, 12:01 AM
#25
RL Community Team
Rennlist Member
Rennlist Member
Well, I am here to call BullSh!t on the article written by the Indy. He is mistaken in many areas of his article.
The amount of oil that impregnates the filter is minimal. To infer that the amount of oil is such that it could mess up the MAF sensor is pure speculation.
A better question/poll should be: Has anyone in any Porsche running a BMC ever had or heard of a MAF failure or alert? I haven't, not even once. I am not talking about any car, any model or any filter. I am saying I have never once heard of any Porsche owner reporting of a MAF issue using pre oiled BMC filters.
The BMC does not pass more dirt through to the engine, complete nonsense and more speculation. If the oil is there to trap more dirt over non oiled then how is more dirt passing through an oiled filter than dry paper filter? His answer is that the oiled filters have larger holes.. More BS.
Here is an excerpt from the tech sheet, unless someone is lying:
"Thanks to the combination of the different oiled layers, containment of all impurities is guaranteed as far as 7 microns, while paper filters generally require total filtration of particles as small as 10 microns. So BMC air filters let more air into the engine while still protecting it better than paper ones.
The amount of oil that impregnates the filter is minimal. To infer that the amount of oil is such that it could mess up the MAF sensor is pure speculation.
A better question/poll should be: Has anyone in any Porsche running a BMC ever had or heard of a MAF failure or alert? I haven't, not even once. I am not talking about any car, any model or any filter. I am saying I have never once heard of any Porsche owner reporting of a MAF issue using pre oiled BMC filters.
The BMC does not pass more dirt through to the engine, complete nonsense and more speculation. If the oil is there to trap more dirt over non oiled then how is more dirt passing through an oiled filter than dry paper filter? His answer is that the oiled filters have larger holes.. More BS.
Here is an excerpt from the tech sheet, unless someone is lying:
"Thanks to the combination of the different oiled layers, containment of all impurities is guaranteed as far as 7 microns, while paper filters generally require total filtration of particles as small as 10 microns. So BMC air filters let more air into the engine while still protecting it better than paper ones.
In my former Volvo tuning life, there were multiple issues with over-oiled filters causing MAF failures. Very common. Likely from over oiling, though. I ran BMC’s on mine and I had a backup paper filter I used when I cleaned, oiled and cleaned off any excess oil. Didnqt make any more power, but sounded damn good.
07-08-2018, 12:28 AM
#26
Burning Brakes
Thread Starter
I have considered this problem when cleaning the 991.2 BMC air filter. Because of the complexity of changing air filters on the 991.2, what I will do is buy a second BMC and rotate the two when the filter needs cleaning. I'll always have a cleaned, oiled, and ready to go filter on hand. More $$ I realize, but it makes life a lot easier. Plus, I got the first one so cheap buying another one, at a higher price, won't be as painful.
07-08-2018, 04:57 AM
#27
RL Community Team
Rennlist Member
Rennlist Member
I have considered this problem when cleaning the 991.2 BMC air filter. Because of the complexity of changing air filters on the 991.2, what I will do is buy a second BMC and rotate the two when the filter needs cleaning. I'll always have a cleaned, oiled, and ready to go filter on hand. More $$ I realize, but it makes life a lot easier. Plus, I got the first one so cheap buying another one, at a higher price, won't be as painful.
07-08-2018, 08:35 AM
#28
Three Wheelin'
Needsdecaf: You quoted me correctly, but not sure you read my post.
Are you saying you have a 991.2 with BMC filter that has caused any malfunction? Based on your reply it was a Volvo and not a Porsche.
Explain?
Are you saying you have a 991.2 with BMC filter that has caused any malfunction? Based on your reply it was a Volvo and not a Porsche.
Explain?
07-10-2018, 02:28 PM
#30
Advanced
Porsche 991 does not have MAF
BMC no issues with my install, however I have heard of others having issues if the filter is too heavily oiled.
In addition the 991 Porsche 911's do not have an MAF but instead have a MAP (Manifold Absolute Pressure) sensor which cannot be fouled by oil from either BMC or K&N filters.
In addition the 991 Porsche 911's do not have an MAF but instead have a MAP (Manifold Absolute Pressure) sensor which cannot be fouled by oil from either BMC or K&N filters.
Last edited by whoddoo; 07-13-2018 at 12:15 PM. Reason: Additional Information