What is the MAF? and what is its function?
01-29-2002, 07:44 AM
#3
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That's what I tought it did....then how is SilverBulletS4 getting around using one?
see thread<ul><li><a href="https://forums.audiworld.com/s4/msgs/662027.phtml">https://forums.audiworld.com/s4/msgs/662027.phtml</a</li></ul>
01-29-2002, 07:48 AM
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Doesn't he still need some sort of airflow sensor?
And if the MAF senses the density of air thru the intake...what is the O2 sensor?
Thanks for the edumacation =)
Thanks for the edumacation =)
01-29-2002, 07:54 AM
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No
If you are using a piggy-back computer or some other sort of fuel air management software. A MAF or MAS is no longer needed since the computer/software will determine how much fuel and air is needed at a given RPM.
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01-29-2002, 07:55 AM
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More than you ever wanted to know about O2 sensors....
<ul><li><a href="http://www.sts.sae.org/membersonly/techinfo/servicetech/oxygen13-17.pdf">Oxygen Sensors (PDF)</a></li></ul>
01-29-2002, 07:55 AM
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There are different ways to measure the incoming air...
The MAF that the S4 uses assumes the intake system is closed. That's why if you vent the air (blowoffs) the car will run RICH since it thinks the air is still in the system, adds the fuel, but alas, there is not that much air in there ;-)
I'm not completely familiar with the way other sensors work, but obviously some allow for blowoffs without getting too rich
O2 sensors are used in the exhaust to determine if the car is running rich or lean - based on the amount of oxygen in the exhaust fumes.
The idea is you want a balanced air/fuel ratio of 14.7:1... rich would be more like 10:1, lean can be straight air
(that would be BAD
-T
I'm not completely familiar with the way other sensors work, but obviously some allow for blowoffs without getting too rich
O2 sensors are used in the exhaust to determine if the car is running rich or lean - based on the amount of oxygen in the exhaust fumes.
The idea is you want a balanced air/fuel ratio of 14.7:1... rich would be more like 10:1, lean can be straight air
(that would be BAD -T
01-29-2002, 08:12 AM
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Actually you are both kinda wrong.
There are 2 basic modes that the ECU goes into Open Loop and Closed Loop.
In open loop the ECU bounces back and forth from the MAP (Manifold Absolute Pressure) or MAF (Mass Air Flow) meter and the O2 sensors to create a mixture. Usually open loop is run when you are at idle or at a steady RPM.
Closed loop is when the car uses predetermined maps of fuel, ignition timing, and boost, but the O2 and MAP/MAF are used for fine trimming.
In open loop the ECU bounces back and forth from the MAP (Manifold Absolute Pressure) or MAF (Mass Air Flow) meter and the O2 sensors to create a mixture. Usually open loop is run when you are at idle or at a steady RPM.
Closed loop is when the car uses predetermined maps of fuel, ignition timing, and boost, but the O2 and MAP/MAF are used for fine trimming.