Engine Fog Horn Sound

[97gtstang01]

OK so the other day I kept hearing a fog horn sound and my idle was surging up and down. Replaced iac and some vacuum lines. No idle issue now but can still hear a faint fog horn sound when reving the engine. Also disconnected the battery to reset the pcm. Any ideas? Is driving me nuts. Could I have a air leak elsewhere?

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[Mattstang04]

Check the intake tube between the throttle body and the air filter. If you still have the stock intake tube it could be pinched near one of the hose clamps and the passing air vibrates the flexible rubber. Same for the silicone couplers on aftermarket CAI kits.

 

[97gtstang01]

Check the intake tube between the throttle body and the air filter. If you still have the stock intake tube it could be pinched near one of the hose clamps and the passing air vibrates the flexible rubber. Same for the silicone couplers on aftermarket CAI kits.

Its got aftermarket intake on it. The couplers are kinda flimsy. Would that make the air filter have a humming fog horn sound

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[trinity_gt]

Its got aftermarket intake on it. The couplers are kinda flimsy. Would that make the air filter have a humming fog horn sound

Yes. Look for gaps or looseness between parts of the intake, especially near the MAF flange.

What you're hearing is the same effect you get when you blow across the top of a beer bottle and hear a resonance that sounds like a humming. You've got an open gap in your intake tract somewhere.

 

[97gtstang01]

Yes. Look for gaps or looseness between parts of the intake, especially near the MAF flange.

What you're hearing is the same effect you get when you blow across the top of a beer bottle and hear a resonance that sounds like a humming. You've got an open gap in your intake tract somewhere.

Thank you for info. I'll check it today after work

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[97gtstang01]

Thank you for info. I'll check it today after work

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So I checked all the connections nothing seems out of place. Could the goose running from the charcoal canister to the purge solinoid being bad cause this?

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[97gtstang01]

Update. So I swapped the new iac valve on my custom towncar to the stang and the sound is gone.now the towncar does it So I got a bad one from parts store out of box.

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