SC93

For those who like technical details.

Kármán vortex sensor explanation:


A Kármán vortex sensor works by disrupting the air stream with a perpendicular bow. Providing that the incoming flow is laminar, the wake consists of an oscillatory pattern of Kármán vortices. The frequency of the resulting pattern is proportional to the air velocity.
These vortices can either be read directly as a pressure pulse against a sensor, or they can be made to collide with a mirror which will then interrupt or transmit a reflected light beam to generate the pulses in response to the vortices. The first type can only be used in pull-thru air (prior to a turbo- or supercharger), while the second type could theoretically be used push- or pull-thru air (before or after a forced induction application like the previously mentioned super- or turbocharger). Instead of outputting a constant voltage modified by a resistance factor, this type of MAF outputs a frequency which must then be interpreted by the ECU. This type of MAF can be found on all DSMs (Mitsubishi Eclipse, Eagle Talon, Plymouth Laser), many Mitsubishis, some Toyotas and Lexus, and some BMWs, among others.[1]

Ali SC3

iTrader: (10)

yup they are frequency sensors, used on all od1 sc300, sc400 and 7mgte's, and the v8 ones are a little larger than the other ones.

hsokhi

Bumpppp

Can anyone elaborate on how this applies to the sc300 maf? I'm having a weird, almost unnoticeable misfire or hesitation under 50-75% throttle. It used to run fine but I took apart my intake to polish the housing on the maf and other aluminum stuff. After putting it back together it doesn't run as smoothly... No check engine light or anything...

Basically I see where the vortices are generated by the criss cross metal grill(don't worry I didn't damage it)
I'm assuming that the sc300 is a mirror type from other threads regarding bad maf, but I don't understand what part the mirror is and where the light pattern is being interrupted, or even generated for that matter. Also after the two metal splitter thingys, there is also a plastic thing with a tiny little .030" slot in it... What does that do?

hsokhi

Update;

The maf needs to be PERFECTLY clean to work without issue. There was a small almost unnoticeable smudge on it from my grimy hands. Cleaned it off. Blew off any dust with compressed air. Now its back to a nice smooth powerband.

But if anyone knows what these different parts of the maf actually do that would be cool to know

SC400slide

iTrader: (11)

If you mean each different part on the MAF/AFM itself, the vane that comes down is the vortex generator which is the part that creates a swirling effect to the air that is downstream, kinda like the wake that happens when a boat passes. The flutter or "wake" is referred to as a "Karmen vortex". From there, the "frequencies of the vortices vary in proportion to the intake air velocity, or (engine load)"

The vortices are metered in the "pressure directing hole" (which is located above the vortex generator), then they act on the metal mirror. "The air flow against the mirror causes it to oscillate in proportion to the vortex frequency." Then comes the illumination from the photo couplers LED to be applied and retracted from the photo transistor. All of this causes the photo transistor to open a 5 volt KS signal to the ECU.

This causes a 5 volt square wave signal that increases frequency in proportion to the increase of the engine load or intake air load. Because of the high frequency, quick nature iof this signal, accurate signal inspection at almost all engine operating requires a very detailed oscilloscope.

Most of the parts that power this part are not in the open so the vane is the only part you can see without taking the MAF/AFM apart.