itsmike177

iTrader: (3)

Hello,

Just purchased a 2008 ISF used with 20k miles. I noticed that when turning off the engine, there is a noticeable "clunk" noise coming straight from the air intake area in the engine bay.

The clunk appears to be from the secondary air intake baffle that "opens" after the engine is turned off. I figure this is the vacuum controlled secondary baffle that opens up at 3600-3800 rpms+.

Just wondering if everyone with an ISF hears the same "clunk" due to the baffle actually "opening" when turning off the engine.

Took a video here Sorry, didn't have a camera man to hold the camera steady.

Thanks for anyone's input

flipside909

I've never heard of that before. Since you're still under the factory 4 year 50k mile warranty, I would suggest bringing it in for service.

ISFAIL

anything remotely resembling a clunking noise in or around the engine bay is never normal and should be looked at asap

I doubt it's coming from the intake

jkeifer3

When I turn my '08 off it dies into silence like a stone being dropped into a bottomless pit. Good luck and keep us posted!

ISF FAN

Never heard that sound before, however wasn't really listening for it. I'll check out mine tonight. Otherwise, on the next service stop, have it checked out.

Joe Z

iTrader: (10)

There is foam on some areas of that flap to keep things quite... It probably came off...

Joe Z

MicaISF

you might want to confirm by disabling your secondary intake to see if the noise would go away. you can do so by disconnecting the electrical connection next to the secondary intake. once it is disabled, the intake will remain open all the time.

itsmike177

iTrader: (3)

I think you nailed it, there is absolutely no foam on the flap or within the secondary intake box area.

Great idea, I will try this out. Any damage or noticeable difference in performance with the secondary intake open 100% of the time?

ISFer

iTrader: (2)

I didn't notice any with mine open for a short time but it's been said that this adversely affects hp and torque very slightly so you won't want to leave it open.

You might also want to consider where that foam went. It could be plugging up the intake downstream somewhere.

C.

Audriuss

The sound u hear is ventilation heater unit. In all IS there is this sound sooner or later...Lexus didn't do anything to fix this problem..I already had two heaters changed...

diagnose: turn on ignition (or engine), make audio off (for complete silence), make ventilation fan at minimum (for less noise) and then, switch for ventilation mode Legs+windshield vs anything without windshield. And I am sure, u will hear this sound always! (just don't switch it fast, cause it changes modes after several seconds...so press and wait, press and wait...it is always there...)

itsmike177

iTrader: (3)

The sound is not the heater core. I was able to narrow it down to the secondary flap, so it's definitely the flap that is making the noise as shown in the video.

UCrazyKid

I've heard of this being a problem in someone else ISF, don't remember exactly where i read it though. They had their airbox replaced under warranty.

ballerx

I have the clunk noise as well but my car has only about 6 k miles on it and it started at about 3k but mine does it when i start the car cold.

Thanks

Phong780

Hey so I have the exact same problem with the flap. Initially I wasn't sure what it was until I came across this thread. I know this thread is over 2 years old but I'm wondering what could I do to fix the clunk? My warranty is up and I looked up the price for a new air box and it's bout $700.

itsmike177

iTrader: (3)

Original poster here. I took it to 3 different dealers for the "flap clunk" when turning off the engine and they stated it was normal. I ended up buying the entire airbox which includes an air filter and the air intake tube for $550 from Sewell.

Upon comparing the old and new "air flap" part of the intake assembly, the old one was missing ALL the foam around the flap. New one still clunks, but it's a soft clunk, not a plastic-on-plastic clunk. I did listen to other ISF's in the lot to see if this happens and they all do when turning off the engine. - soft clunk.

No issues with the out of pocket air intake after 2.5 years since replacement.