I have a 99 4x4, ext cab, 4.0
and i bought a KKM air intake, and It might be a coincidence but, when the weather is HOT and the AC is on, I get this Terribly annoying Humming sound. Does anyone know WTF that is ?? its driving me NUTS, and i cant seem to find an answer. any help would be great.. thanks

Define "humming sound".

If you mean your engine sounds like an airplane is spooling up down there, it's cuz the weather is hot, your a/c is on, and your clutch on your fan is locked, causing it to move a buttload of air around to keep your engine cool. And when you add a KKM in to the equation, it makes it even louder, because you can hear the KKM sucking in more air being an open filter and all.

Im talking WAY outa the NORM. When the car is moving and i put it into gear, (its a manual) the sound Imediately goes away. When i am stop and the Car is Ideling Its so loud that Heads turn. Like someone is Blowing a fog horn.. its unreal.. I have actually had people come up to me and ask me what that was. its really strange.. NOT your normal AC is on, and more air is being used for cooling. But i understand what your saying. I had some one suggest to me that its my "IAC", but i dont know what that is..
Thanks for your reply

Jason

Whoa, that's just wierd. I've never heard of that, but I'm no mechanic either ;)

IAC = Idle Air Control valve. 99% sure it's located near the throttle body, but I'm sure someone will correct me if I'm wrong. Though I don't see how that would cause a humming sound.

BTW, nice truck, I like 4X4's :)

I cleaned my IAC and it didn't help. I just cleaned my MAF and we will see how it works. I know what you mean about the noise. It is REALLY ANNOYING

I've heard of A/C clutches doing this when they go bad or needed to be recharged or oiled....I don't remember which one, but one of the three.

I've had the same thing happen with mine--this problem gets posted at FR.com all the time. Looks like every single Ranger owner who has this intake has run into this inevitable problem in the summer. Some have said cleaning out the idle air control, MAF, and fabricating a heat shield addresses the problem.

btw Black4x4, do you have any pics of your truck you could post? That is one SWEET lookin' ride..

Same as gts007 here, I've always heard it's the IAC. Never did understand what causes it to make the noise though. With the hood up, where does it sound like the noise is coming from? Try pulling off just the filter and see what happens, or manuever your intake tube around a little. Maybe it's a combination of intake air and vibration. Does your motor speed up when you turn the A/C on and it's at idle?

It is the IAC. The oil from the KKM filter clogs the IAC. My '98 4.0L Splash made the howling sound. The only way to end the howling sound is to have the IAC replaced. The IAC is a cylinder-shaped piece, mounted on the right side of the intake, near the throttle body. When your engine starts to howl, try tapping on the IAC with a screwdriver. Sometimes the howling will stop.

Take your truck to the dealer and have the IAC replaced. The howling will stop. I've found this to be the only way to stop the howling. Cleaning didn't work for me.

Hope this helps,

Jim Lee:drunk:

Thanks alot!!! that sounds like what i will do. Do you know about how much its going to cost me to replace my IAC??

Ill Post weather or not that fixed the problem..
Thanks again..

...around $80.00 if your truck is out of warranty. I got mine changed just before the warranty expired. Good luck. It should end the humming sound.

Jim Lee

I had that obnoxious howl too. It was coming from that little brace that comes with the KKM kit( the one that supports the cone. If it gets to vibrating just right it gives off that really loud humm, that won't go away. I just got some rubber washers from HD and it hasn't done it since

I'd think that the dealer would be unwilling to replace the IAC for free if the noise is being caused by an aftermarket intake?? It seems they dislike all Rangers with aftermarket parts on them..at least at my dealership.

Thx for the pic Black, that's one nice truck.

If you try to take the truck in and get the IAC replaced under warranty, I would take the extra time to reinstall the factory airbox. GTS is right, most dealers frown upon aftermarket mods.

Good luck on getting rid of the howl,

Jim Lee