99 tahoe cabin noise - sounds like vacuum

[718frankb]

i dont know were just fishing here ,maybe rotor to contact connection ?my truck is perfect also,idles at 650 never stumbles or shakes no codes ...

 

[osukellen]

Went and checked the cap...doesn't seem to be anything off about it, but it definitely sounds like it is coming from there. Hmmmmm...any thoughts?

 

[718frankb]

egr tube off the back of the header????????

 

[osukellen]

I'll check that tomorrow...wouldn't it be throwing a code if that were the case? Anyone else have this problem?

 

[spicewood1]

Get ready to laugh - what are spider injectors? This engine runs great no codes ever, did have to change the IAC - was bad and made the idle rpm wander up and down. A bad vacuum leak usually makes the rpms jump, try it - disconnect your booster hose.

 

[fyremanpat]

what happens if you put the hvac on recirculate?..if it goes away or quiets up a bit it might be from the flap in there...ive got a k&n and has a gnarly vacuum sound from the intake at idle

 

[spicewood1]

Well I notice my recirculate is not working, or at least the button is not illuminating when depressed What is the flap you mention?

 

[fyremanpat]

that might be the problem. if its stuck open then your are getting outside air...and more noise..with the flap close you are recirculating the air inside the cabin...passenger side under the dash. you can see it if you stick you head down there. you may not have noticed it before from the rough idle like you said...this is just a thought though

 

[osukellen]

Went over mine yesterday, and it is definitely the distributor making the noise. You can hear the noise get slightly lower when you roll the electric windows up or down, similar to headlights dimming when using something electric in the car. It sounds a little like a vacuum leak from inside, but once you get under the hood it is easy to tell it is not.

I don't know why/what would cause the distributor to make this noise, and my truck is running fine, so I am going to leave it. I can live with the noise, the not knowing is what was bothering me.

Spicewood-Spider injectors are what we use in our truck. They look like a spider...8 legs.
http://www.oreillyauto.com/site/c/detail/BOR0/63886.oap?year=1999&make=Chevrolet&model=Tahoe&vi=1353721&keyword=injectors&pt=02521&ppt=C0024

 

[718frankb]

have you upgraded your plug wires ? thats when i noticed it