Deafning Noise At Idle!

[gonowhere]

2002 RX300 AWD with 110k. There is a deafning noise, sounds like subwoofer is working, at idle on all shifts. When I turn the steering wheel, the idle rpm goes up just a little and the noise is gone. Is there a way to adjust the idle rpm a little higher? The ivac/throttle has been cleaned, but no noise reduction is noticed. Thnaks very much.

[lenore]

You might look under the car and see if the flex pipe on the exhaust is cracked, it is just under the oil pan of the engine. This would cause a booming sound. If so , get it repaired at an independent muffler shop, (a lot cheaper) normally around $100...... by the way if it is cracked you might feel some exhaust coming out of the crack.

[code58]

2002 RX300 AWD with 110k. There is a deafning noise, sounds like subwoofer is working, at idle on all shifts. When I turn the steering wheel, the idle rpm goes up just a little and the noise is gone. Is there a way to adjust the idle rpm a littl[/b]e higher? The ivac/throttle has been cleaned, but no noise reduction is noticed. Thnaks very much.

I don't believe you can adjust the idle, that is controlled by the IACV. As Lenore said, it's probably the exhaust, at least that's the first place I'd look.

[gonowhere]

Thanks for the suggestions, but no exhaust leak could be found. I think the noise is due to car vibrating in resonance to the engine at low idle rpm (just below 750 rpm). I can feel the car vibrates just a tiny little bit when parked. At slightly higher rpm, the sound is gone. Went to dealer before, they pretended that they could not hear the noise. I have to play radio loudly to cover the noise.

[code58]

Thanks for the suggestions, but no exhaust leak could be found. I think the noise is due to car vibrating in resonance to the engine at low idle rpm (just below 750 rpm). I can feel the car vibrates just a tiny little bit when parked. At slightly higher rpm, the sound is gone. Went to dealer before, they pretended that they could not hear the noise. I have to play radio loudly to cover the noise.

GNW- I would certainly think the people at Lexus would have checked- but have the motor mounts been checked? I seem to remember that the mounts in the RX are rather sophisticated and CAN be problematic. Defective or broken motor mounts can DEFINITELY cause resonance and other strange noises that are amplified into the interior of the vehicle. It isn't a possibility of catalytic convertor that is coming apart inside is it? They can definitely cause strange noises like that. You can buy a mechanics stethoscope cheap at Harbor Freight and have someone else in the car operating it in the way you described while you listened with the stethoscope. They definitely amplify the sounds- you could hear a gnat !Removed! at 50 ft. with one of those!

[lenore]

Hey code58 my car also has that low rumble, it has 158k miles, Idle is at about 650 rpm, and the engine doesnt appear to vibrate, I just chalked it up to a ten year old car with higher mileage. Thank goodness my hearing is going a little bad, it is really less noise than my 2005 Ford F150 at idle. I know none of my motor mounts have ever been replaced and the original cats and mufflers are on the car. I had the flex coupling replaced about 4 years ago...Cold weather seems to acentuate the sound...

[code58]

Hey code58 my car also has that low rumble, it has 158k miles, Idle is at about 650 rpm, and the engine doesnt appear to vibrate, I just chalked it up to a ten year old car with higher mileage. Thank goodness my hearing is going a little bad, it is really less noise than my 2005 Ford F150 at idle. I know none of my motor mounts have ever been replaced and the original cats and mufflers are on the car. I had the flex coupling replaced about 4 years ago...Cold weather seems to acentuate the sound...

Lenore- I stand by what I said in my last post. To me those are the 1st. 2 things that I would investigate. Motor mounts are often quite sophisticated now compared to what they used to be. Even Ford used liquid filled mounts on the Taurus 15 yrs. ago. Trust me, after a lifetime in automotive work my hearing is suffering too, but if you haven't ever used a mechanics stethoscope I can tell you for a fact you'll hear things you never dreamed you could hear! The mounts are pretty easy to check normally just by putting it in D and R and torqueing the engine (braked). But I don't think a bad mount will always show up in that simple test the way they used to. As I said, some of the mounts are quite sophisticated and I know some of them even have sensors on them, though I am not knowledgeable enough to know what that's all about.