Hissing sound '05 xc90 V8
 

When I accelerated I hear a hissing sound coming from the driver's side engine compartment. The sound is much more noticeable while driving. The hissing sound disappears when you let off the accelerator, but the sound gets louder when you accelerate hard. When I try to locate the sound from under the hood, I cannot hear the hissing sound, even when the engine gets revved by a helper. The exhaust appears sound, with no leaks. Any ideas?

found the problem.

@Hkusp45 I have the same noise, but I can't figure it out. What was the issue?

When I replaced my subframe bushings, the steering column was still attached to the steering gear box. This caused a rubber boot to disconnect from the spindle on the steering shaft. The boot is located by the gas pedal. So because the spindle was not inserted in the hole of boot, the spindle was spinning around the steering shaft like a bearing. The boot keeps the spindle from spinning.