LOUD whistling noise

[BryanB]

Hi ya'll,
I have a 99 X OHV 4.0 with a MAC cold air intake. Whenever the temp goes up outside (and ONLY when it is warm), the silly thing creates a VERY loud vibrating/whistling/resonance noise. I was wondering if anyone else has this problem? It seems to be coming from the intake manifold since I can hear it from the throttle body. Stock induction doesn't make the noise however. Any thoughts or ideas?

 

[briwayjones]

Hi ya'll,
I have a 99 X OHV 4.0 with a MAC cold air intake. Whenever the temp goes up outside (and ONLY when it is warm), the silly thing creates a VERY loud vibrating/whistling/resonance noise. I was wondering if anyone else has this problem? It seems to be coming from the intake manifold since I can hear it from the throttle body. Stock induction doesn't make the noise however. Any thoughts or ideas?

Sounds like the classic IAC whistle. Your IAC valve needs cleaning and/or replacing. Search for "clean IAC" and you should get tons of info.