MikesLexo

Hi guys

Possible common problem and need help. Just replaced the air filter, clean maf sensor with maf cleaner and clean throttle body. Notice a humming noise doesn't matter park or drive. Reset ecm and have been driving it for 2 days now. Still notice the annoying hum and took the engine cover off and notice humming comes directly from intake manifold and gets louder as rpm raise.. Super annoying and can't figure it out. Could it be the intake air control valve stuck ( aka Snorkel ) cause this ? Does anyone know what the air valve control purpose ? Does it serve the engine mount and more ? Again humming was not there until TB/MAF cleaning and new air filter. Thanks again

tomr51

look fow a vaccuum hose not connected around the air filter pod there are a lot of vaccuum connections that can be easily disconnected

MikesLexo

Thanks for the advice.. I saw the vacuum diagram under the hood and checked all the vacuum line. Idle RPM seems to be good at 750-800rpm. Drive and power is good, just the annoying humming/whining. Definitely it's on the intake manifold but not sure what can make it hum and growl

Margate330

Hi mikedlexo,

Do you have any check engine lights and codes?

If you have a significant vacuum leak whistling and making noise you may see it with a lean code or witness elevated fuel trims.

MikesLexo

Just hooked up a scanner and no pending codes. Also just replaced all vacuum lines new trying to eliminate the problem. Resetted the ecm again and seems better but just whining compare to before serviced

tomr51

from left field, is the air filter lid correctly fitted and tightened?

MikesLexo

i thought I had the lid on wrong during initial installation. Went out and rechecked, left field are in and right side is bolted down. Gaps seems good

MikesLexo

FYI.. There's many reason why a car make humming, squeaking, clunking and etc... I have owned and worked on many cars in my life. I never have a problem what I have with this car where high pitch humming noise from intake manifold itself un-tampered during the tune up. Recently, I have done all idlers, belts and waterpump on the RX350. Figure I'll be good for a while since all new quality parts
were installed by me. The problem end up being the alternator causing intermittent overcharge voltage causing irratic symptoms I'm having with this car. Ordered a Denso OEM alternator and installed today. No more humming or any weird noise where I can justify. FYI alternator R&R sucks on this vehicle. Probably the worst I ever done ! Hope this help someone and recommended replacing the alternator around 120k. The pulley design is called a decoupler pulley. These are apart of regular maintenance to replace at 100k. For the price of the pulley, you mine as well replace the alternator since it needs to be off the car and I will never do this job twice and use OEM