Hey guys
recently i have a problem with this whistling sound after i switch off my car and it goes like a whistling spiral sound and ive checked there’s no leaking on any vacuum lines .
at first i thought it was the aftermarket Air inlet/Box because this sound occurs only after changing an Aftermarket Air Inlet/Box but then i try removing the air inlet so left only the Throttle Body itself and i do the same thing start and turn off the car the whistling sound is still there
btw my idling is perfect and it doesnt fluctuate everything seems fine
i am just wondering is there a fix to it

 

The sound is most likely coming from compression remaining in the cylinder leaking past the intake valve. It's probably fine but you may want to do a compression and leak down tests just for peace of mind.

 

Okay a compression leaking test .
car is running perfectly fine right now its just weird after switch an aftermarket CAI it has the sound but right now even removing it still has the sound .
Hopefully compression test is ok
it only makes the sound when i switch off the engine

 

The sound was probably there before but you just didn't notice it. Stock intakes are designed specifically to reduce noise and a CAI will make intake sounds louder.

When you turn your engine off, compression will be built up in a cylinder. This pressure wants to go somewhere and there is three ways it can escape: through the rings, through the exhaust valves or through the intake valves. Because none of these are perfect seals, it will escape eventually. A leak down test will probably show your valves are slightly leaking. This isn't unusual in a older engine and nothing to be too concerned about unless it is really bad. It could be something as simple as the valve lash being set too light. Likewise, a compression test is also likely show that while the engine doesn't make the same numbers as it did fresh from the factory, they are probably fine.

In other words, this is normal and your engine probably isn't going to explode. If you want to be extra safe, do a leak down and a compression test but I wouldn't bother. I would probably just check the lash and call it good.

 

It is almost certainly this. Source: I've had three different D15s and a D16 with aftermarket intake setups, they all made odd noises on shutdown. With too-thick steel tube and an AEM filter a D15B7 almost sounded like a really teeny blow off valve.

 

Okay guys ive done the compression test everything is fine but theres leaking around the green area on the gauge so i assume its fine yea

 

have u watched the video ? Does it sound the same ?

 

I did indicate that none of my engines sounded identical in this, but I always had at least 16" of tube and filter on the mani if running (I do not enjoy rebuilding blocks). So no, it isn't exactly the same, because I never heard it right at the TB. I made my last comment trying to consider those variables, and have not changed my mind.