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      08-28-2012, 08:40 PM   #14
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Drives: 2011 BMW 335d
Join Date: Sep 2010
Location: Murland

iTrader: (4)

Originally Posted by chenry View Post
OK so took a look at the air box again and realized that I could just pop the snorkel tube along with the "valve" out of the air box with relative of course I did. I took a look at the valve and it is regulated by a spring and it's normal state is in a closed the engine demands more air and the vacuum inside the box increases the spring is pulled in thus allowing access to more air for the motor (albeit very hot air given its position as discussed before) so that ends the debate over a cold air start or a cooler for the turbos etc...

But here's the interesting thing...before I put the valve tube back into the box I buttoned up the airbox closed the hood (bonnet for those of you across the pond) and took the car for a spin around the block....I hit 75% throttle and BAM limp mode...took the car home reinstalled snorkel and thought I would need to use my reset tool but before doing so I simply restarted the car (no limp) and took it for a hot lap and no obviously my car likes this little thing just where it is - that said Im scratching my head why my car threw an error with this minor change while others are running open element filters with no problem / oh well maybe my jbd has something to do with it but that said note that I did not touch the JBD during this whole process

So you now have my 2-cents on the matter
Just a guess, but if the actuator opens to allow more air in while under load and you closed it up, you effectively restricted the airflow, which probably triggered the limp mode. With a cone filter, the box is removed so there is no restriction at this point - granted your engine is sucking in more hot air this way; it would kind of be like leaving the actuator open all of the time.

Question: what is at the end of the snorkle? Is there a filter or is it just an open tube?