Stock intake air trouble

My brother has a 2008 X-Runner with about 45,000 miles on it. He was complaining about it sucking too much air. He says when it's cold it will sometimes shut off or stall, because it sucks to much air. I rode with him the other day and you can hear where it's sucking too much air, kinda sounds like a farting noise coming from the intake but more in the right fender where the stock intake sucks air from. We took a look at it and we saw nothing. He has taken it to a local mechanic and a Toyota dealership and they can't find anything wrong with it. He has a stock intake. Any ideas?

 

Since it sounds like it's coming from the fender would you suggest that we take the inner plastic off and look in there for a leak. He's the mechanic not me so I really wouldn't know.

 

Could be the opposite too . . . something might be blocking the intake which would cause the 'sucking sound' due to the air velocity increasing (but decrease in volume). Don't rule out the havoc a small animal can cause in a vehicle. Mice build nests pretty quickly and squirrels like to store food in small crevices.

At our old house (rental) there was a carport that my wife and I would park in. Literally every day I'd have to clean out my wife's intake airbox because mice would build an entire nest overnight and/or store seeds and grain in it. If I missed doing it, there would be a slight sucking sound and the seeds would rattle around inside the airbox. Luckily they never got past the filter.

 

So this "farting" sound hapens at all engine RPMs, throttle position, load on the engine, etc? Or are there certain conditions under which it does it? I'm guessing it is intermittent if the dealership techs couldn't find anything wrong with it?

 

Just to throw it out there... a "farting" noise from the intake can also be a symptom of a severe exhaust blockage, often a cat's honeycomb coming loose and turning sideways, although it would also have a bad loss in power (and could blow a headgasket if it's pushed).

 

The only time I've heard it is at low speeds, but I can't be sure it's not happening at faster speeds because of all the other noises (exhaust, road noise, radio, etc.) My brother said that when he took it to Toyota and the other shop it wouldn't make the noise and while we were trying to look at it it didn't make the noise either. So it's not constant but it happens fairly often. So it's really hard to tell what it is when it doesn't always happen and my brother is looking to get rid of his truck but I think this is one of the things that's keeping him from selling it.

 

I have this exact same symptom on my 2007 V6 TRD. It seems to happen more when the engine is cold and traveling at low speeds. If I feather the gas pedal, I can hear the sucking/wheezing noise...I can even get it isolated to a specific range of RPM's, then when I press the accelerator down further the noise subsides. There is no noticeable affect on power or gas mileage. I also notice the sound coming from the front, passenger side area but was unable to find any leaks or blockage.

Please let me know if you isolate the problem or find a fix as I'd like to fix my unidentified intake/vacuum leak issue as well. Thanks.

 

The 1GR's intake tract has only one resonator. It depends on the filter, carbon trap, and corrugation in the tube to quiet it down, which compared to a conventional stock intake system does ...not a whole lot.

Just about every throttle body ever made makes a whistle somewhere in the 2-4" Hg vacuum range, you just can't always hear it.

Random tidbit, I used to accelerate "at the whistle" in my Civic when I had a CAI. That was about 3" Hg and by keeping the ECU out of open loop would give a very nice boost in fuel economy.

For what it's worth, my truck makes this warble too. Funny thing is, it does it when it's pushing ignition timing the farthest and giving the best mileage. I think it's pulling timing on the intake cam thus making the weird noise, but that's pure speculation.