I noticed that the additional air intake flaps are always open, I read it online that it should only be open when the engine speed reaches 3500rpm. Anyone know why & how to resolve this?

 

I think they are vacuum actuated. Check to see if the hoses are disconnected or broken. Can try to spray some lubricant on the hinges too.

 

Thanks 970gts. I just changed cylinder 6 ignition coil. In order to get more space, I disconnect the part (no idea what it is for) which shows in picture red circel. After change, I forget to reconnect it and start engine (connected now). Now I can feel slight vibrition, rpm is slight fluctated at idle and flaps oped. Not sure why.

 

Reconnecting a part that should be connected is always a good thing. As you noted originally, at idle the flaps should be closed. Can you get your fingers or screwdriver through the grill and see if the flaps move freely when the engine is off (there will be a bit resistance because the flaps are spring-loaded). A little bit of lubricant on the hinges can't hurt. Check for loose/broken vacuum lines again.

 

Is there a reason to want/keep them closed until high RPM? Isn’t the more air made available by three filters better than the one central one? Sounds like a good modification for me to go the other way.

If it helps any, when I was having the rough idle/almost stalling issue the round circled thing pops up as the engine self revved itself to stave off stalling.

 

You would certainly want the flap closed when parked to keep the critters out. There may also be a higher probability of water intrusion if open during steady state operations.

 

Thank you! Those are great points I didn't originally consider.