What is this sound/noise?

[BARRACUDA1968]

Been putting some miles on the new build and making some 10 psi pulls. Yesterday a few seconds in to the pull I hear an air horn kind of sound. I checked all my hoses and they are tight. Kind of sounds like its in the dash but hard to tell?

All CAI piping is tight etc.

I did have my dash apart this spring to install a new stereo and my HVAC controls aren't functioning properly so could there be a vac line under the dash sucking air if I managed to knock one off the HVAC controls? Just guessing here.

Any ideas?

We're going for a cruise today and I'll try and get a video of it.

 

[greeneyegi]

plug the main vacuum that goes to the hvac,see if it still does it?

 

[BARRACUDA1968]

Here's a video of it. At the end of the video you will hear it. Now it sounds like it's coming from my AEM WB gauge? I'll have to find my paperwork on it and see if the dumb thing has an alarm on it or something? Didn't think it did? I'm just rolling in it at 10 psi.

 

[phil_jordan]

Wow. That is odd. Do you only hear it under acceleration? What about immediately after turning the car off? Do you hear it then?

 

[BARRACUDA1968]

I just hear it under accel. I swear its coming from my WB gauge but after doing some research my AEM doesn't have a warning feature I can find? If it's going off it's because I'm pig rich.

No noise when shutting car off. Weird.

 

[mtocrs1]

I would disconnect the vacuum lines to dash on the right side of engine bay. It sounds like a blend door or the HVAC controls switching. My old 76 century made a noise that sounded similar anytime I changed the temp setting.


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[BARRACUDA1968]

I'll give it a try.

 

[X Ray]

If your HVAC controls is not functioning properly get that fixed first....may see the issue go away.
May be affecting the blend door as mentioned by mtocrs1
Climate Control Vacuum Valve ..... ACDelco part number 15-71389 or equivalent may fix this. Good luck.

 

[Fast4Ward]

Been putting some miles on the new build and making some 10 psi pulls. Yesterday a few seconds in to the pull I hear an air horn kind of sound. I checked all my hoses and they are tight. Kind of sounds like its in the dash but hard to tell?

All CAI piping is tight etc.

I did have my dash apart this spring to install a new stereo and my HVAC controls aren't functioning properly so could there be a vac line under the dash sucking air if I managed to knock one off the HVAC controls? Just guessing here.

Any ideas?

We're going for a cruise today and I'll try and get a video of it.

Some months back another member had the same problem and also posted a video. Cant exactly remember but may have been turbo related. Not sure

 

[BARRACUDA1968]

I think I remember that thread and it was turbo related. My turbo was rebuilt by Bison so I'll rule that out at this point. When I get some time I'll do some more investigating.

 

[TurboDave]

Sounds more like boost pressure leaking from a small hose, likely one of the HVAC hoses popped out somewhere near the controller.

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[BARRACUDA1968]

Well that would explain why my defrost and vent etc aren't working.

Need to get that fixed coming in to fall. I plan to drive it till the snow flies.

My girlfriend pointed right at the dash when it went off and I looked at wideband on the A pillar. Neither one of use were drinking either.