[deviation01]

I was looking around and noticed this. Is it just to check and see how dirty the filter is?

[838]

Uuhh uhhh... i know, i know this one... a passage to narnia?
... oohh oohh wait... dats d other door 🚪

... may it b the air intake resonator flap? let loose excess air to dissipate?

[deviation01]

Originally Posted by 838

Uuhh uhhh... i know, i know this one... a passage to narnia?
... oohh oohh wait... dats d other door 🚪

... may it b the air intake resonator flap? let loose excess air to dissipate?

I wonder because it opens inward into the filter media. I sort of wonder if really its a window to check how bad the filter is

[838]

Yeaahh stil a mystery thou... unlikely able to see its dirtiness with full enclosure... more often than not, will still open up the cover and clean replace, dirts will always be on it... oohh well, will juz leave it to d experts in door/window passage way or waever it should be

... interesting find stil

[deviation01]

Originally Posted by 838

Yeaahh stil a mystery thou... unlikely able to see its dirtiness with full enclosure... more often than not, will still open up the cover and clean replace, dirts will always be on it... oohh well, will juz leave it to d experts in door/window passage way or waever it should be

... interesting find stil

It also doesnt seem to be operated by any "computers".

The door opens in but the spring on it is very heavy so you really need to press.

The filter media covers that too so I am inclined to believe its air going in vs out since the door opens inward as well.

That side of the filter media was clean clean so nothing really was hitting it.

Unless there is a rod or something that pushes that door open. It looks like maybe something connects to it when its in place?

[Tangent]

Wild guess, but anti-water ingestion device? If that flap is higher than the normal intake path, in case of going through deep enough water the restriction from pulling in the water would be enough to overcome the spring, open the flap, and pull air in from that higher point.

[deviation01]

Originally Posted by Tangent

Wild guess, but anti-water ingestion device? If that flap is higher than the normal intake path, in case of going through deep enough water the restriction from pulling in the water would be enough to overcome the spring, open the flap, and pull air in from that higher point.

Good guess but this door sits at the lowest point of the intake box. Sort of "vents" to the ground.

[838]

Ooo ooo ... this might might came into light... dat opening flap under the intake box can b likely a secondary air intake or a diverter valve, lookin at its position... it may allow additional air to enter the engine compartment, to enhance coolin?... may also be to help reduce engine noise by dissipating some of the intake sound?... or or... possibly serve as a pressure relief valve, equalizing air pressure in the intake system?... back to dissipating, oohhh well, dat stil too many maybe also 😄... if stil none of it even close, best stil, get it to the expert who added that flap there

[deviation01]

Originally Posted by 838

Ooo ooo ... this might might came into light... dat opening flap under the intake box can b likely a secondary air intake or a diverter valve, lookin at its position... it may allow additional air to enter the engine compartment, to enhance coolin?... may also be to help reduce engine noise by dissipating some of the intake sound?... or or... possibly serve as a pressure relief valve, equalizing air pressure in the intake system?... back to dissipating, oohhh well, dat stil too many maybe also 😄... if stil none of it even close, best stil, get it to the expert who added that flap there

[RMS27]

My guess is it is the flap that opens and closes depending on if the air recirculation is on or off.

[deviation01]

Originally Posted by RMS27

My guess is it is the flap that opens and closes depending on if the air recirculation is on or off.

Most likely but what or how does it do that. There is only a spring and the trap door opens inwards. It needs quite the force to push it in.

If its airflow it has to come from outside. I suspect its some magical thing as the filter media was clean on that side. So no flow really happens.

[BigMart]

I've seen these before.

With the engine running if you close off the intake completely (cold air feed) the engine has gotta take air from somewhere so the spring yields and it sucks through the little window.

Not sure what circumstances would completely close off the air feed - maybe a completely blocked air filter? - but I suppose it would prevent the engine from stalling. (don't think it would run very well but at least it would run).

I think it was an Audi I saw it on first , didn't know what it was for but was able to bung a big rag in the air duct before the filter and see the flap open.

On reflection , a safety thing in case of a blocked air filter?

[deviation01]

Originally Posted by BigMart

I've seen these before.

With the engine running if you close off the intake completely (cold air feed) the engine has gotta take air from somewhere so the spring yields and it sucks through the little window.

Not sure what circumstances would completely close off the air feed - maybe a completely blocked air filter? - but I suppose it would prevent the engine from stalling. (don't think it would run very well but at least it would run).

I think it was an Audi I saw it on first , didn't know what it was for but was able to bung a big rag in the air duct before the filter and see the flap open.

On reflection , a safety thing in case of a blocked air filter?

I think this one makes the most sense. The spring will yield at certain force of suction and it will prop that open inwards. I think this is the winner!

[3y3scream]

https://www.nforcd.com/products/bmw-...ate-intake-mod

https://www.nforcd.com/products/air-...ot-climate-mod

I believe its made for an extra adapter for hot climate BMWs, take a look at the link.