Whistling noise

I took my daugher's car (98 SC2 AT w/53,000 miles) into the muffler shop for
replacement of the flex pipe and resonator exhaust system was sounding
noisy). After leaving, the vehicle now exhibits an air hiss (like vacuum
leak type noise) that increases with increased throttle (not necessarily
speed related - just putting gas pedal farther down the floor) When the
throttle is released the noise disappears at any rate of speed, and the same
applies when shifting the tranny from 2nd to 3rd to OD and back again. I
had the muffler shop re-check the installation and welds and they indicate
all is well underneath. The sound eminates from the front end of the car
but exact location is tough to determine, though its definitely under the
hood somewhere. There is no loss of power or anything else, just the
hissing noise as if there is air being forced somewhere it shouldn't be.
There were no loose hoses or fittings. This has been a great car so
far....absolutely no oil burning or reliability problems, other than
replacing said flex pipe and resonator.
Any ideas out there? Thanks in advance

 

I wonder if they bumped the intake and the hose from the throttle body to
the air cleaner is loose or has come off. With the radio off and the car
sitting in the driveway, when you turn the key off do you hear a big whooosh
sound?

 

Did you check the other end? Intake leaks around anything that sucks air?

The first thing I would do is get my wife out there with a thick cotton rag
and have her "plug" the tailpipe as best as possible once the car was
running. That would temporarily build up pressure and reveal any exhaust
leaks better... If you could do it on a lift, that would be even better...

Joe - V#8013 - '86 VN750 - joe @ yunx .com
Ask me about "The Ride" on July 31, '04:
http://www.youthelate.com/the_ride.htm

I'm not a total idiot... I am after all, missing parts.

 

I think you are hearing the air being sucked into the intake. Mine makes
a quiet whistle when the gas pedal is in the floor. Maybe you couldn't
hear it before because the exhaust was noisy.

 

There is absolutely no noise coming when turning off the key. I did pull
the air filter out and the housing appears to be very tight. Sounds are
tough to detect where they come from specifically, but it does sound like it
comes from the passenger side of the engine compartment and the air filter
is on the opposite side. And with the car parked and reving the motor up,
the noise only comes briefly during the quick revving process of the
engine.....its much more prevalent when the car is under load and actually
moving, though the noise has no relation to vehicle speed or wheel motion.
The noise is also very noticeable and isn't just a light whistle or hiss.

 

If you said squealing I'd suspect a belt or tensioner.

This model year doesn't have an air pump does it? How about the PCV valve
or line - they in good shape? There's another hose (vent line) from the
valve cover to the intake. That's about all I can think of.

 

No...definitely not squealing...I had that last winter and replaced the
sepantine belt which solved that. This is more the sound of air than the
sound of mechanical lubrication.