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Old 08-04-2012, 09:13 PM
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dc_wright dc_wright is online now
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Mein Auto: '96 328iC, '04 325Ci
If it's a flapper door type MAF the flap moves a shaft that changes the resistance in a potentiometer.
Digital multimeters don't take continuous measurements, they take a sample, analyze it, convert it to digital data that can be displayed on the LCD display. High end DMMs do this at a high rate and cheap DMMs do it at a slow rate. Your DMM may only be taking a measurement once every second or once every half second so you might not see a smooth linear transition from low to high. All that being said, assuming you're moving it continuously through it's range of motion, the radical swings in resistance make the MAF suspect.

The graphing DMM DF is referring to does the same as a DMM but it saves each sample and plots them in graphical format on the display. It's not unusual for a graphing DMM to be able to process 100K samples per second or more. High end graphing DMMs (which are really battery operated, handheld oscilloscopes) can take 20M samples per second, but it's pretty rare you find anything in a car that requires that kind of sampling bandwidth.

7K rpms equates to 117 revs per second which electronics wise is pretty damn slow.
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