Hissing Throttle Body Normal?

[waqar_lionheart]

Hi guys,

Sorry for so many posts recently. Just wanted to find out if it's normal to hear a constant hissing noise from throttle body at idle. My rpm are fairly steady.

This is only there at idle.

Regards,

Waqar

[gazza1286]

At idle the butterfly inside the throttle body is fully closed. The air required to mix with the fuel makes its way into the inlet manifold via drilled channels within the throttle body. These channel allow a pre-determined volume of air to pass through - enough to maintain idle. any breaks in the seal onto the intake manifold could allow more air into the intake and effect tickover. The hissing your hearing could be this or a leaking hose onto the throttle body or intake manifold.It could be normal. Such hissing subsides as soon as the butterfly opens as air will rush in via the airbox and equalize the pressure.

Can't offer any more help.

[Konrad C]

Think whistle.