Loud humming. 98 4.0 OHV

[vdaily89]

There is a loud humming that comes and goes under the hood. It is on the passenger side of the engine. It is so loud that you can hear it in the house when my wife pulls in. When it is making the sound, if I let off the gas and then tap the pedal, it stops immediately. Any ideas?

Also, my wife said it almost died on her 3 times yesterday when she pulled to a stop (still in gear). Once she drove it for a while and it warmed up some more, it quit. Any ideas?

thanks in advance

 

[Buckshot]

Ford mating call. Look up IAC.

The dying at idle is more likely the MAF sensor...look for cleaning procedures....simple fixes for both.

The little plastic cap on the IAC can be completly removed to fix the mating call, although some guys have tried to clean it - I just yanked it. No ill issues except for an occassional BUT MUCH QUIETER whistle at about 4k RPM.

Hope those threads help...post if you can't find them....

 

[vdaily89]

Thanks Buckshot. So did you just take the cap off the IAC and leave it off or did you replace it? I'll search for both.

 

[dogfriend]

Wooooo

 

[Buckshot]

I just took the cap off and left it off....some people talk about cleaning it, so maybe it has more value than I think.....

 

[dogfriend]

I don't think it is a huge deal to leave the cap off. I'm pretty sure the purpose of the vent is to let air in and out from behind the piston that regulates the bypass air. If they didn't have the vent, the piston wouldn't be able to move freely. The downside of leaving the cap off is that dirt may eventually build up and prevent the IAC from working properly. It won't create a vacuum leak, because the IAC piston is between the vent and the manifold port(s)

vdaily89 -

The problem your wife was reporting may be due to a bad IAC valve. If it isn't working right, it may not let enough air in for proper idling. The symptoms are a low idle speed and stumbling when trying to take off from a stop. This is because the IAC is supposed to let in more air to maintain idle speed when you shift into D; if it isn't letting in enough air, the truck will stumble or stall.

 

[Crispy Niggets]

I have the same problem, my explorer doesnt die but it seems like it gets bogged down and stumbles to find the right gear when accelerating, I thought the humming was because of my k&N air intake

 

[Mbrooks420]

Both problems are because of a bad IAC. They are cheap, and I would replace, other than leaving the cap off. If you are going to drive a highly computerized car you may as well maintain it.

 

[Crispy Niggets]

I took the little cap off and for the past few days I havn't had any problems of humming of weird acceleation- awsome!