Vacuum type howling

[Victor Perkins]

I have a 98 explorer sport 4.0 ohv manual transmission. Between about 1500 rpm - 2000 rpm, I get this annoying rather loud vacuum type howling coming from the air box. Doesn’t matter if I’m stopped or driving, it comes on about 1500 rpm and keeps howling up to 2000 rpm. When I come up to a stop light the rpm’s come down slowly from 2000-1500 and rests around 1000. I have changed the air filter (K&N cold air kit), mass air flow sensor, throttle body (from original to KBB)-nothing seems to stop it. Any ideas?

 

[Mbrooks420]

Clean or replace your IAC. If it’s doing it constantly it’s probably got a ruptured diaphragm.

 

[Victor Perkins]

Clean or replace your IAC. If it’s doing it constantly it’s probably got a ruptured diaphragm.

Clean or replace your IAC. If it’s doing it constantly it’s probably got a ruptured diaphragm.

Thank you, that might have worked!

 

[C420sailor]

Classic vacuum leak symptoms. If it isn’t the IAC, something else is letting a bunch of air in, making the idle hang