I've had a whistling sound from under the hood for the last couple of months. It's not that huge of an issue, but I think it's getting louder and I don't want the engine getting any unmetered air, esp. with my upcoming mods. A buddy of mine said he heard it from his car when we were on our way to work one morning.

It's only present during acceleration with more than 25% throttle and only between 2500 and 5k rpms. Because of this, I am unable to locate it while revving the engine in my driveway. I've taken my propane torch and run the gas (no, I did not light it ) around the intake tube, plenum, and any vacuum line I could find. The idle did not change. As a matter of fact, the idle is perfect, always has been. Accelleration is smooth; there is no stumbling; mpg is normal (about 18-20 mpg combined); I've never received any error codes; everything seems ok. I took it to the dealer for it's final (read: ONLY) dealer service before the warranty expired, and they made no mention of anything unusual.

'03 G35 Coupe, 607xx miles, current mods: K&N drop-in/Z-tube; 5/16 isothermal spacer; topspeed headers; kinetix hfcs; custom true dual (whistling was present before hfcs and exhaust were installed); custom grouding kit; engine damper; power duct on/off makes no difference in whistle

I wonder if this is normal, as my loaner car ('05 G35 sedan) also had a bit of whistling under the hood, same as mine.

What other tricks are there to finding vacuum leaks or exhaust leaks? I don't have a steamer handy, but I'm trying to get my hands on one. Any other ideas?

 

Have you tried putting the stock air box back in just to exclude that theory?

 

Could it be the midget ***** under your hood blowing the whistle?

 

No, I keep her in the trunk.

I'll try putting the stock airbox back in this weekend and see if that helps any.

 

i think it might be your z-tube making the whistle...i also remembering reading

that it was caused by air coming into our engines...i've heard two different

whistles while driving my car...one from the z-tube, the other i was not able

to pin point, but it would only happened once in a while...i havent heard it for a

really long time...

 

its the air rushing in due to the Z tube and hitting the throttle plate its common when you have a Ztube or CAI....remember when you took out your stock air box and you see all these empty containers attached to it that dampens the sound and also supplies air for deceleration and stuff like that i dont know the exact terms...but wit modification comes sacrifice....guarantee you hear it more when you first start up and drive hit the gas and take off ...your car will sound like a beast and you will realize your whistle noise...you can also hear it if you carry out a gear in that RPM range you said you hear it in....just feather the throttle a little and you will hear the pitch change

 

Yes, it's likely your intake. Different intakes will magnify the whistling sound.

 

I don't mind the whistling at all - I just wanted to make sure this is "normal", considering the '05 sedan dealer loaner I drove for 5 days had the same whistle under the same conditions. Thank you for the reassurance all. :thumbs: