MAF Screen
Originally Posted by cicerofire
Where did that information come from? I have had the screen off my MAF for two years, no change in air fuel ratio on any gauge I have or any other for that matter. Some upgraded MAF have no screen at all,Except SLP and they say this They dont seem to think you need to change any setting on your PCM? On the flip side of things I never noticed a bit of difference with the screen out. The OEM MAF was replaced along time ago with an SLP, and even then no "adjustments" were needed to the VE in the PCM.
and RPM are enough to tell it what's going on, up through
the intake. Only changes from manifold on out through the
exhaust need VE tweaking (presuming the stock table is
true to begin with).
I wouldn't take SLP's word for anything, on technical matters.
The best way to judge the effectiveness of screen removal
on airflow is to look at your MAP vs RPM curve at WOT. Like
the MAP at 3000RPM vs the MAP at 6000RPM, say. The MAP
drops quite a bit on full-stock setups. If your MAP drops by
1kPa (ref 100kPa BARO) that's 3-4HP on the table. The drop
is the sum of filter, lif, MAF, hose, TB restriction. The more
improved high end breathing (intake, heads, cam, exhaust),
the more you challenge the intake side restrictions and the
more MAP drop you will have. Conversely if you are dropping
only a couple of kPa or a couple tenths PSI at your upshift
point, might as well not get too excited about "free mods"
because your engine has all the air it needs, more or less.
For now.
TECH Addict
Joined: Mar 2004
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From: Fat Chance Hotel
Originally Posted by YellowToy/A
technical
The sensor measures the mass of air that is going into the engine over time. This is in pounds per minute of air. What the PCM is trying to do is find out how much air is in cyl. If the MAF sensor is wrong the PCM will put in more or less fuel to get the air/fuel mix what it thinks it should be. The big part of what the senor measures is velocity of the air over time to get mass of air that goes into the engine over time. The mass of air has to be corrected for things like temp and density.
The sensor measures the mass of air that is going into the engine over time. This is in pounds per minute of air. What the PCM is trying to do is find out how much air is in cyl. If the MAF sensor is wrong the PCM will put in more or less fuel to get the air/fuel mix what it thinks it should be. The big part of what the senor measures is velocity of the air over time to get mass of air that goes into the engine over time. The mass of air has to be corrected for things like temp and density.
BTW, it came to me whilst in the shower. I always think clearer in the shower...
Jimmyblue
I not think that "Only changes from manifold on out through the
exhaust need VE tweaking" Any change that lets more air into the engine will change the VE. Removing the screen will change the VE a small amout just as porting the throttle body. I think that if you port the throttle body you will need to port the MAF to make a change. If the throttle body is the choke point then doing something to the MAF will not make a change.
I think where this started was that if you that the screen off the MAF it will change the calibration. To recalibrate the MAF you have to have a good VE table.
What do you think?????
I not think that "Only changes from manifold on out through the
exhaust need VE tweaking" Any change that lets more air into the engine will change the VE. Removing the screen will change the VE a small amout just as porting the throttle body. I think that if you port the throttle body you will need to port the MAF to make a change. If the throttle body is the choke point then doing something to the MAF will not make a change.
I think where this started was that if you that the screen off the MAF it will change the calibration. To recalibrate the MAF you have to have a good VE table.
What do you think?????
TECH Addict
Joined: Mar 2004
Posts: 2,336
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From: Fat Chance Hotel
That would be the raw output of the MAF which the PCM uses against the MAF calibration table to calculate airflow. If you were to change the values in the table, you effectively change what the PCM believes the incoming airflow rate is.
