I need Help with Stock 95Z28 MAF sensor readings
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Joined: Jul 2003
Posts: 1,103
From: Hawaii
I need Help with Stock 95Z28 MAF sensor readings
Does anyone know at what grms/sec does a stock 95Z28 A4
is supposed to read while at idle (575RPMs) and at WOT (5450 RPMs)?
Mine reads:
6grms/sec at 575 RPMs
and
228grms/sec at 5450 RPMs
I read a post where people it was reported that a good MAF was reading 10 or 11 grms/sec at idle and 240 to 250 at WOT. It was also mentioned that a ported MAF on the very same car was reading only 6grms/sec.
Now I am begining to think my MAF is probably way off and most likely on its last leg.
Can anyone confirm this?
Also I would probaly buy a Z06 MAF if mine is on the way out. Has anyone logged any WOT Runs with it? Its the Calibrated Z06 MAF comparable in calibration to the Stock MAF?
a New stock MAF is going for 199 here in Hawaii but a LT1 calibrated ZO6 MAF goes for about 150.00. A lot less.. You can see why I am interested.
Marvin
is supposed to read while at idle (575RPMs) and at WOT (5450 RPMs)?
Mine reads:
6grms/sec at 575 RPMs
and
228grms/sec at 5450 RPMs
I read a post where people it was reported that a good MAF was reading 10 or 11 grms/sec at idle and 240 to 250 at WOT. It was also mentioned that a ported MAF on the very same car was reading only 6grms/sec.
Now I am begining to think my MAF is probably way off and most likely on its last leg.
Can anyone confirm this?
Also I would probaly buy a Z06 MAF if mine is on the way out. Has anyone logged any WOT Runs with it? Its the Calibrated Z06 MAF comparable in calibration to the Stock MAF?
a New stock MAF is going for 199 here in Hawaii but a LT1 calibrated ZO6 MAF goes for about 150.00. A lot less.. You can see why I am interested.
Marvin
Last edited by MentalCaseOne; Jan 5, 2004 at 05:17 AM.
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Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
Originally posted by shoebox
Sounds pretty normal for the readings. Read more here.
I have seen posts of people that have bought and used the calibrated Z06 MAF and said it was fine. I don't think you need a MAF, though.
Sounds pretty normal for the readings. Read more here.
I have seen posts of people that have bought and used the calibrated Z06 MAF and said it was fine. I don't think you need a MAF, though.
MAF (Mass Air Flow):
In a "mass air" engine control system, as used in the 94 and later F-bodies, the PCM only needs a few pieces of information to manage the air and fuel mixture. The most important is the amount of air entering the engine, to be used for combustion with the correct amount of gasoline. More specifically, it needs to know the "mass" of air, or the number of pounds or grams of air that entered the engine to be used to burn the gasoline.
The Mass Air Flow (MAF) sensor measures the mass of air entering the engine, expressed in "grams per second" or "pounds per minute". The ScanMaster displays only the metric units - grams per second (gps).
Note - to convert grams per second to pounds per minute:
grams/second = pounds/minute x 7.56
Example: 30.0 pounds/minute x 7.56 = 226.8 grams/second
At idle, the air mass flow will range from as low as 6gps to as high as 10gps. If you reading is suspiciously low, you may have a vacuum leak. If it is suspiciously high, and the idle speed is correct, it's most likely a "faulty" or "miscalibrated" MAF. This problem is typical of "home ported" units.
At WOT, the peak air flow in a stock, normally aspirated engine, with a 5,800rpm rev limit will be about 240gps.
The MAF sensor works by internally measuring the temperature of the air coming into the system. It then uses the wires to heat the small amount of air that is actually touching the wires, a fixed number of degrees above the incoming air. By measuring the electrical power required to heat the air, and knowing the specific heat of air, the MAF sensor can calculate the "mass" (or roughly "pounds") of air entering the engine. It then converts this signal to a variable frequency output. Inside the PCM, there is a calibration table that converts the frequency to a "mass air flow" rate.
The calibration chart is based on the specific configuration of the stock MAF sensor and air inlet ducting. If you change any component of the system, you upset the calibration of the sensor. The "screen" - actually a honeycomb, made out of thin paper/foil - is there to provide a uniform flow of air across the full face area of the sensor. In this way, since the amount of air flowing past the sensor wires is the same as the amount of air flowing in other parts of the sensor, it can calculate the total air mass flow through the sensor by measuring only the small sample of air that touches the wire. Removing the "screen", or removing the dividing wing in the housing inlet and outlet halves destroys the calibration of the sensor.
In a "mass air" engine control system, as used in the 94 and later F-bodies, the PCM only needs a few pieces of information to manage the air and fuel mixture. The most important is the amount of air entering the engine, to be used for combustion with the correct amount of gasoline. More specifically, it needs to know the "mass" of air, or the number of pounds or grams of air that entered the engine to be used to burn the gasoline.
The Mass Air Flow (MAF) sensor measures the mass of air entering the engine, expressed in "grams per second" or "pounds per minute". The ScanMaster displays only the metric units - grams per second (gps).
Note - to convert grams per second to pounds per minute:
grams/second = pounds/minute x 7.56
Example: 30.0 pounds/minute x 7.56 = 226.8 grams/second
At idle, the air mass flow will range from as low as 6gps to as high as 10gps. If you reading is suspiciously low, you may have a vacuum leak. If it is suspiciously high, and the idle speed is correct, it's most likely a "faulty" or "miscalibrated" MAF. This problem is typical of "home ported" units.
At WOT, the peak air flow in a stock, normally aspirated engine, with a 5,800rpm rev limit will be about 240gps.
The MAF sensor works by internally measuring the temperature of the air coming into the system. It then uses the wires to heat the small amount of air that is actually touching the wires, a fixed number of degrees above the incoming air. By measuring the electrical power required to heat the air, and knowing the specific heat of air, the MAF sensor can calculate the "mass" (or roughly "pounds") of air entering the engine. It then converts this signal to a variable frequency output. Inside the PCM, there is a calibration table that converts the frequency to a "mass air flow" rate.
The calibration chart is based on the specific configuration of the stock MAF sensor and air inlet ducting. If you change any component of the system, you upset the calibration of the sensor. The "screen" - actually a honeycomb, made out of thin paper/foil - is there to provide a uniform flow of air across the full face area of the sensor. In this way, since the amount of air flowing past the sensor wires is the same as the amount of air flowing in other parts of the sensor, it can calculate the total air mass flow through the sensor by measuring only the small sample of air that touches the wire. Removing the "screen", or removing the dividing wing in the housing inlet and outlet halves destroys the calibration of the sensor.
Thread Starter
Registered User
Joined: Jul 2003
Posts: 1,103
From: Hawaii
Thank you ShoeBox and Injuneer, that is some good information.
I have one Question though..
Shoulndt this read "if its suspiciously Low" ?
What I mean is on a "Home ported unit" as compared to the Stock unit, the inner diameter tubing "area" inside the MAF itself "where the sensors are located" shouldnt it be greater than the Stock unit and therefore "the Air velocity" at any given identical RPM should read lower and not higher than the "stock MAF" for the same engine?
I am using my logic here and Injected SS seems to have confirmed my theory when he (for testing purposes) swapped his stock MAF for a Home Ported one and found out the grms/sec dropped from 10 or 11 into 5grms/sec I believe.
here is the thread:
http://web.camaross.com/forums/showt...hreadid=208553
What do you guys think? Injuneer? Shoebox?
Marvin
I have one Question though..
If it is suspiciously high, and the idle speed is correct, it's most likely a "faulty" or "miscalibrated" MAF. This problem is typical of "home ported" units.
Shoulndt this read "if its suspiciously Low" ?
What I mean is on a "Home ported unit" as compared to the Stock unit, the inner diameter tubing "area" inside the MAF itself "where the sensors are located" shouldnt it be greater than the Stock unit and therefore "the Air velocity" at any given identical RPM should read lower and not higher than the "stock MAF" for the same engine?
I am using my logic here and Injected SS seems to have confirmed my theory when he (for testing purposes) swapped his stock MAF for a Home Ported one and found out the grms/sec dropped from 10 or 11 into 5grms/sec I believe.
here is the thread:
http://web.camaross.com/forums/showt...hreadid=208553
What do you guys think? Injuneer? Shoebox?
Marvin
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Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
When you alter the MAF sensor, it destroys the calibration. The problem is, this "destruction" is not predicatable, and it is not necessarily the same from engine to engine. The MAF sensor may read erroneously high or low at various points through the range of flows that it measures. My experience, based on reviewing numerous data logs for people indicates that ported (and often even descreened) sensors tend to read higher than actual air flow at idle.
You can't just look at the fact that the diameter got larger so that the average velocity across the open area went down. The problem is that the screen promotes a uniform velocity of the air flow across the full cross-sectional area. When you remove the screen, it is possible the you now have a less uniform flow velocity, particularly at low flow conditions where you are seeing laminar flow. The velocity is higher in the middle of the sensor, and lower at the edges. Since the sensing wires are only in the center of the meter, they see a higher velocity, higher heat loss, and hence "measure" higher mass air flow. And, remember, the sensing wires only measure the small part of the flow that is touching them, and then extrapolate the flow across the entire face of the meter, ASSUMING that flow velocity is uniform across the full face area.
You can't just look at the fact that the diameter got larger so that the average velocity across the open area went down. The problem is that the screen promotes a uniform velocity of the air flow across the full cross-sectional area. When you remove the screen, it is possible the you now have a less uniform flow velocity, particularly at low flow conditions where you are seeing laminar flow. The velocity is higher in the middle of the sensor, and lower at the edges. Since the sensing wires are only in the center of the meter, they see a higher velocity, higher heat loss, and hence "measure" higher mass air flow. And, remember, the sensing wires only measure the small part of the flow that is touching them, and then extrapolate the flow across the entire face of the meter, ASSUMING that flow velocity is uniform across the full face area.
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