Hi there,

My teg has a very light hissing sound at the low rpm range, around 2k to 2.5k. Once the rpm goes up it is smooth and very quiet. This is especially noticible at cold temp. My gas milage is still good, between 29 to 32 mpg for 80% freeway driving at 75-80mph and 20% San Francisco city driving.

I brought it in the dealer and they say it sounds perfectly fine to me, but I am a bit worried and is wondering if it is normal.

Here are more info:

1997 RS auto
100% stock
68k miles mostly freeway
5w30 Mobil1 since new, except when bought into dealer for every 30k services they put in whatever oil and honda fluid.
Never had any powertrain problems.

 

IAC valve does that on mine..probably same thing. Does the intake hiss for a few seconds when you turn the car off?

 

No it doesn't hiss when I turn the car off. Interesting that I only hear it from the interior, not when I am next to the open hood.

The sound seems to be in sync with the combustion of the engine. Sorry this might sound silly but do you think human ear can hear the blow by or any valve misadjustment? Or any leak around?

By the way, my idle is very low at around 500rpm to 700rpm.