How to check if the flap is open @ 4.5k rpm, other than listen to it.

I've suspected that the flap on my JCW intake is not open, or not close at all, since I do not hear any difference sound, before and beyond 4.5k rpm.
Thank you.

 

That's easy. Just have someone put it in neutral and push the accelerator until it hits 4500 - 5000.

You reach behind the airbox (in the space towards the windshield) with your hand and feel if it opens or not.

That's what I did anyway.

 

I would check the vacuum hoses first. This connects from the JCW cold air box, to a "T" piece in the feed from the compressor. This provides the vacuum to open the flap. Reach down behind the airbox, you can feel the flap and see if it opens as the car is revved. There is a good chance this piece of vacuum hose is either disconnected or has perrished.

 

Thats the one

 

I wondered this as well when I had the JCW intake. So I took the flap out.

mb

 

Just check the vacuum hose where it connects to the air box, its been prone to come loose a lot I had to zip tie mine to keep it on.

 

Flapless here as well.

 

I had the wife rev it up to 4500 while I had my hand on the thing. Yep the flap works. I like the way the JCW is quiet until you give it the boot.

 

Put a K&N ru-3130 in, and you'll really hear it!

 

^^ +1