Talk:Mass flow sensor

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Merged a couple versions of automotive mass air flow articles into one, and joined them under the more generic article of mass flow sensor. Sattyam 23:55, 21 May 2006 (UTC)

[edit] VZ commodore does not use hotwire

VZ and later commodore's use a "coldwire" MAF system where by the air passing over a tiny sensor causes inductance, this inductance is converted to a frequency which is then fed to the car's ECU. This frequency is related to the amount of air (CFM) passing over the unit.

The mesh on the MAF is used to smooth out airflow to ensure the sensors get the best chance to get a steady reading.

CORRECTION:

The cold wire sensor does not measure inductance of air. The inductance of air can be affected by any number of contaminants or conditions, such as humidity, gas vapors or particulate matter. A Cold air sensor is simply a design that uses a cold wire (non heated) element to measure air temperature coming into the sensor as well as a heated wire in order to correct for changes in air density and temperature having an effect on the output.

More information: http://www.kemparts.com/TechTalk/tt06.asp

Correction needed:

" Manufacturers claim that a simple but extremely reliable test to ensure correct functionaldiscarded and an OEM replacement installed."

[edit] Hot wire sensor

Currently we have, The amount of current required to maintain the wire’s electrical resistance is directly proportional to the mass of air flowing past the wire. Unless it is made of some sort of magical material that has infinite resistance when there is no air flow, that can't be right. Directly related I would believe, and maybe even linearly related, but not directly proportional. Aij 03:59, 6 September 2007 (UTC)

Hot Wire Sensor: this is false (backwards) "The wire's temperature increases with the wire’s electrical resistance, which limits electrical current flowing through the circuit. When air flows past the wire, the wire cools decreasing its resistance, which in turn allows more current to flow through the circuit. As more current flows, the wire’s temperature increases until the resistance reaches equilibrium again."

Should read: "The wire's temperature DEcreases with the wire’s electrical resistance"

--75.18.117.165 03:36, 24 October 2007 (UTC) deleted stuff .

"When air flows past the wire, the wire cools decreasing its resistance, which in turn allows more current to flow through the circuit. As more current flows, the wire’s temperature increases until the resistance reaches equilibrium again."

http://www.autoshop101.com/forms/h34.pdf 75.18.117.165 03:52, 24 October 2007 (UTC)

Also, if the resistance reached equilibrium the current flow and thus the voltage would never change... how would the control unit be able to detect changes in mass? 75.18.117.165 03:36, 24 October 2007 (UTC)