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Hissing noise coming from behind under the intake manifold??
1993 Chevrolet Camaro

Hissing noise coming from behind under the intake manifold??

(1993 Chevrolet Camaro)
Turn key into the on position I can hear a hissing noise coming from behind kind of underneath the intake manifold. When you start the car the idle is a little high and it is shifting a little rough almost just going into gear instead of slipping. What could it be I have changed the throttle position sensor ,the EGR and still dose it.
Tags: chevrolet, camaro
2 answers & 1 comment
Popular Answer
on May 25, 2019
Hissing noise when key is turned to the ON POSITION is likely fuel pressurization inside the fuel rail.

Professional *hands-on* testing which includes fuel pressure test as well as full OBD1 scan test is recommended..
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on May 25, 2019

Due to different configurations - engine ‘size’ is always important information to have!
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on May 25, 2019
Hissing noise when key is turned to the ON POSITION is likely fuel pressurization inside the fuel rail.

Professional *hands-on* testing which includes fuel pressure test as well as full OBD1 scan test is recommended..
Sign in to reply
on May 25, 2019

Due to different configurations - engine ‘size’ is always important information to have!
on May 25, 2019
Hello, sounds like a possible vacuum leak. Testing should be performed to pin point the location of the leak, many technicians would "richen" the area around where you hear the hiss noise and see if the engine running improves. This is done with a gas like propane introduced into the area.

I would not recommend any of this for the "backyard" mechanic, but would suggest seeking some professional assistance for what is likely an easy diagnostic test for someone with the proper equipment taking the appropriate safety precautions.
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