hiss sound during idle

mohsen · Post by **mohsen** » Wed Aug 29, 2007 9:04 am

i have lanos 1997-1.5- SOHC 135000 km
iam hearing hiss sound during idle
what can i do
plz help

daewoomofo · Post by **daewoomofo** » Wed Aug 29, 2007 10:02 am

what part of the car is it comming from, how loud is it?

mohsen · Post by **mohsen** » Wed Aug 29, 2007 12:01 pm

it is coming from something near throttle body
low loud

Turtle_Wax · Post by **Turtle_Wax** » Wed Aug 29, 2007 2:58 pm

If it hisses when you release the throttle it may just be the idle valve doing its job allowing some air passed.

kinkyllama · Post by **kinkyllama** » Wed Aug 29, 2007 6:41 pm

mohsen wrote:it is coming from something near throttle body
low loud

Check for a vacuum leak. One of the rubber nipples probably came off one of the extra hose connector thingys on the throttle body

mohsen · Post by **mohsen** » Thu Aug 30, 2007 6:46 am

thanx all

mohsen · Post by **mohsen** » Thu Aug 30, 2007 1:11 pm

what do u mean by release the throttle

Turtle_Wax · Post by **Turtle_Wax** » Thu Aug 30, 2007 5:30 pm

mohsen wrote:what do u mean by release the throttle

When throttle is in its closed position. If I blip my throttle (at the throttle body) As the revs die down to normal idle I get a high pitch whistle sound from the idle speed valve which sounds like an air leak but its the air the valve is allowing past the TB to maintain a correct idle. When I first heard it I was checking everywhere for an air leak before I realised it was the ISCV doing it's job.

Damic · Post by **Damic** » Fri Sep 07, 2007 9:25 am

Recently, I had a similar hissing sound from the engine compartment of my Lanos 1,5 and I as well as several friends and even mechanics couldnt locate where the sound comes from. Than, I took a stetoscope, like medical doctors have, and with ease locate the source of hissing sound. The culprit was wright small rubber hose that comes to head cover below EGR -valve. On the rubber hose, there was a little crack, almost unvisible.

This tool, as sound amplifier, is almost forgotten, but was was very common among old car mechanics.