Humming coming from air intake

westend wrote:
I have the same engine and the same sound. It is the MAF device. I should clean it up and I'm sure the sound will go away but mine's been like that for 85K miles. If I install a new air filter, the sound usually goes away for a few thousand miles.

I haven't noticed any engine performance differences since this sound appeared but it can be noisy at stop lights and such. As was posted, opening the throttle body with the accelerator pedal eliminates the hum.

Thanks that is good to know. What is a MAF device and how do I clean it up?

I have the same engine and the same sound. It is the MAF device. I should clean it up and I'm sure the sound will go away but mine's been like that for 85K miles. If I install a new air filter, the sound usually goes away for a few thousand miles.

I haven't noticed any engine performance differences since this sound appeared but it can be noisy at stop lights and such. As was posted, opening the throttle body with the accelerator pedal eliminates the hum.

I replaced the air filter but the sound is still there. I don't think it is affecting performance, but I don't want anything to break on the trip!

Oops forgot to include the year of the RV. It is 2004 E350. Also just checked all the hoses and housing and no cracks, etc that I could see.

Also depending on the age, check your emissions warranty. Possible some of the throttle body/idle air control components are covered for an extended period-provided they're defective.

No after market system. I will check for cracked hoses and housing.

Air is sucked under a vacuum through the throttle body which is a massive restriction at idle. Generally without an air filter or silencer there is a hissing noise. Additionally there often is an "idle air control" which is a finer tuning device to precisely meter air into the system at idle. Just my thought at the time something in there may be vibrating possibly harmlessly. It may be something to get checked out. Put a new filter in, and be sure the ducts/hoses are not split at the least. Aftermarket air cleaner systems, if you have one, are much noisier than stock.

I remember the sound always being there. But my wife says she thinks it was louder yesterday on our trip. I think it might have been a little louder. I would describe it as more of a buzz, not a vibration. This morning it was intermittent and would come on and off and then stayed on. It has never done this before and that's why I am a little worried. I think it is air going through the throttle body but it is a distinct sound. Is there a fan that blows are into the throttle body or does it just suck the air in? Sorry for my ignorance.

How did the sound come about? Is this a change from the way it sounded before? Try to narrow down on the hum. Is it more of a buzz or vibration? Is it the sound of the idle air going through the throttle body? Is it bearing noise from an engine accessory? Do you have stock air filter?

I'd start by looking for intake air leaks or vacuum line leaks.