IAC port hissing in TBI

[thfonz98]

Recently replaced intake gasket(coolant leaking), TBI gasket, which has solved my varying idle in gear(dead on 500rpm perfect) but idle RPMs vary a bit still.

I also have a loud hissing coming from my IAC port with my air cleaner Assy. off, ran my winaldl and IAC is showing steady 39 till closed loop then jumps to 55 shortly after. No codes.


So as Ive seen, people ask if the IAC is hissing in previous posts but never address the response to said question. So this is my question: Hissing IAC port, normal?

91 k5 tbi 350, Odometer broke@ 218k (prob around 250k now)

 

[4X4HIGH]

The hissing you hear is probably not coming from the IAC port but rather the air passing the throttle plates. There is a way to seat the IAC valve so that you can verify what i'm saying.

Jumper the A and B terminals on the ALDL connector

Turn the key on and wait for 30 seconds (this seats the IAC valve).

Now go under the hood and disconnect the IAC connector

Now you can remove the jumper between the A and B at the ALDL connector and start the engine.

 

[GalDemSuga]

Recently replaced intake gasket(coolant leaking), TBI gasket, which has solved my varying idle in gear(dead on 500rpm perfect) but idle RPMs vary a bit still.

I also have a loud hissing coming from my IAC port with my air cleaner Assy. off, ran my winaldl and IAC is showing steady 39 till closed loop then jumps to 55 shortly after. No codes.


So as Ive seen, people ask if the IAC is hissing in previous posts but never address the response to said question. So this is my question: Hissing IAC port, normal?

91 k5 tbi 350, Odometer broke@ 218k (prob around 250k now)

just getting broken in