E46Fanatics - View Single Post - MAF reading question
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Old 11-12-2011, 12:52 AM   #2
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Join Date: Oct 2009
Location: Oakdale, MN
Posts: 778
My Ride: 02' M3 SMG, 02' 330i
Before jumping to the MAF did you first check for vaccum leaks? More likely than not your culprit right there, MAF's don't generally fail all that often and generally fail from over-oiled air filters, or damage while being handled, or improper "cleaning."

Your above mentioned method also seems to pertain to MAP sensors not MAF sensors

As the names imply (Manifold Absolute Pressure sensor) and a Mass Air Flow sensor. Two entirely different things my friend, and our cars do not have a MAP.

Case in point your units as measured from the LD capture were 0.43 pounds a minute, or 3.22 grams a second which is the "mass" of air entering the engine and the time interval it is entering at.

Where as the reading of 26.5Hg is actually a reading of pressure or in this case roughly 83kPa (which I would like to point out your source was wrong again)

Lets think about this at 26.5Hg you're talking about almost (close enough) to two atmospheres of air, do you using common sense think that the air is thicker at sea level or in the mountains? Clue: its thicker (more dense) at sea level so you're reading will be higher at sea level than at altitude. So your source is backwords for starters, and secondly his numbers are pretty decently off, since you're not going to have essentially twice the atmospheric pressure entering the engine at idle. This number would be close to WOT at sea level....

End of story. Check for vaccum leaks in the intake boots report back.
330i - AA Tuned, Headers, UUC Stage I LW FW, e36 M3 Clutch, UUC SS Clutch line, BMW Performance Intake, Evo Sport Pulleys, BMW Performance Cross-Drilled Rotors, Hawk HPS, BW SS Brake Lines, BW Solid Guide Bushings, BMW Performance CF Strut Brace, H&R Sways, H&R Sport Springs, Bilstein Sport Shocks, Powerflex Bushings, LED Tails, Clear Sides/Turns, Black Grill, Mtech 2, CF Splitters

M3 - Not enough room to list

Last edited by lejeunebimmer; 11-12-2011 at 01:16 AM.
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