mikemu30

Obviously not😀 My own experience - we own a 350 - it has a mild drone which I honestly don't even notice after nearly four years of ownership. I have had 450 loaners several times and they sound EXACTLY THE SAME as my wife's 350. Oh well.

vmoldovan

I bought my RX when it was 3 years old, in Feb 01, 2020, full warranty till the next Jan. It has a clean CARFAX history, serviced at a Lexus dealer. It is Lexus certified, whatever that really means nowadays. Paint is all original, all is in almost new condition. I inspected every inch of it at the dealer before I bought it from them. There is no sign of any accident nor I was in any while owning it. I know few things about cars with accidents myself, so I am quite certain of my determination.

It is dreaded droning.
As I showed in the picture above, adding the weight reduced it quite substantially.
Now that I have weight there, and it's reduced, it would be hard to record it, with road noise. When I have a chance, I will try but it may take a while before I get to it (taking it off and recoding original full drone).
I will post it when I have it

P.S. And even if I have it, I am interested in any ideas to fix, not reaffirmation that it's drone. I drove loaner 350s too and I heard it as well. there is youtube video too of its sound, it's hard to mistake it

gadgetman1

Well, it certainly sounds like you did your homework & know something about these vehicles. There has to be something that’s different on your model - maybe something was changed out for warranty or other service work. Something is clearly different about your 450h, vs. mine & others that don’t get any drone. Have you ever had the transmission serviced? This is just a long shot, but consider getting a sample of your transmission fluid sent to Blackstone Labs for analysis. Perhaps there is something in your transmission that’s causing the drone. Sometimes mine will shift up to high gear (not sure what that really is on a CVT) at lower speeds & it causes a bit of a low frequency vibration/noise, but it’s really not noticeable, unless you are listening for it. I’m very sensitive to that sort of stuff, but mine is so subtle, that it doesn’t bother me. On my Camaro SS, if I shift up to 6th gear (manual transmission) before 50 mph, it really makes some annoying noise & vibration & let’s you know it doesn’t line that gear.

vmoldovan

I am not aware of any transmission work that ever was done to my vehicle, at least not while I own it. Transmission in this vehicle is silky smooth and I have no reason to even touch it.

Let's bring some science into this.

RX 450h has V6. V6 produces three exhaust pulses per revolution (V8 > 4 pulses and 4-cyl > 2). My sports mode tachometer shows drone at approx. 1700 to 1800 RPM. let's pick 1750 RPM. 1750 R(evolutions) P(er) M(inute) / 60 sec => 29.1666 times a second * 3 pulses per second = 87.5 Hz frequency. Thus, this is a natural exhaust frequency at 1750 RPM of V6 engine.

I used Sound Spectrum Analyzer app, to split sound low frequencies and here is what it showed, see below.
It confirmed beyond any doubt that frequency of this spike matches exhaust frequency at that RPM and thus by definition is what is called "exhaust drone". that is how I understand it. Anyone is welcome to correct me here.
I still have additional Toyota weight on my exhaust pipe so drone is mitigated with it. It seemed like 50% originally, sometimes it seems somewhat less but nevertheless mitigated.
Also it's been really cold (-18 C, 0 F) where I live and that was the temperature when I drove to make this capture, and according to my personal observations it appears that cold tones down this drone firther.



I need to buy this app to save audio recorded. I have fancy sound recorder and I wil try to record sound inside a cabin when it warms up a bit and then use different spectrum analyzer on that audio file.
So these are my additional facts about my drone.

Helmholtz tube (or J tube) at 1/4 wave length, 38" in length would likely kill this drone. Math I used is: Length= 1100 / Drone freq / 4 * 12. That is one potential fix.

But before that, I will gather more data and will take it to Lexus again. Exhaust is under 96 months or 80,000 miles emmision warranty. I don't think I should be doing custom solutions to my vehicle, not yet.

P.S. The goal of good exhaust design is to mitigate these frequencies but it appears in my case Lexus exhaust fails to mitigate it sufficiently and it reaches cabin and my ears. Or something is defective about my exhaust and at 57K KM or 35K miles it should not happen.

gadgetman1

That’s some great research you’ve done! However, it still doesn’t answer the question as to why YOUR vehicle is so much worse than say mine or anyone else? What’s different? I will say that on a test drive of a 350 & on a few of the 350 loaners I’ve had, I got a pronounced, sharp, rattle from the exhaust at certain RPMs. It was loud, just like the YouTube video. That’s the sole reason I didn’t buy the 350. My 450h has never done that.

I suggested this before to someone, about installing exhaust wrap on your pipe. That should quiet it down some & doesn’t involve removing anything or welding. It’s worth a try before doing an exhaust modification. If I were in your shoes, either the exhaust would go or the whole car. This is too expensive of an automobile to play these kind games & put up with stupid automakers & dealers.

eddie420

I have been meaning on purchasing a set of the Steelman Wireless ChassisEAR just so I can diagnose exactly which area is causing the most drone. Been so busy with life that I have not bothered yet, but seeing @vmoldovan 's post above is giving me an itch to get it.

Here is a clip at the 13min 20sec mark to give a demonstration on what these are.

703

no such issue on the 3rd Gen Rx450h. They are getting dated inside but very very reliable and issue free. I would go to say you get less problems with them than the 4th Gen RX.

gadgetman1

That is an awesome piece of equipment!! Clearly, it doesn’t appear the Lexus techs are using anything as sophisticated or useful as this! I’m really eager to find out what is making these horrible drone noises & why some have it & others don’t. I’m very impressed at both of your work on this. If you want something done right, you have to do it yourself.

rxtimes2

It seems that each vehicle is different. The drone frequency can be effected by something as simple as torque wrench spec. degradation when installing things like engine mounts and exhaust systems. I had to move the anti- resonant weights around the exhaust system until I found the sweet spot. My 16 is now much quieter than my stock 17. There are literally pages describing where owners have placed weights in this thread. Some successful, some not.

Lorn

I have a 2018 RX and sometimes there is vibration while at a red light and the AC is running

NCRX350

Same here with and without AC. Starts happening as soon as you shift into gear and RPMs drop. Feel it whenever stopped.
2017 RX350. Muffler TSB, Hesitation TSB already applied.
Vibration goes away as you you give it some gas and RPMs rise.

TrueOX

Guys,

I have an RX350L 2018. The engine noise is quite loud and there is major vibration during idling in the drive gear. Iding in Park isn't bad but you definitely feel the vibration when I am idling in gear.
I brought the Lexus dealer and have them checked and they can't find anything wrong with it and they said it is normal for that version of RX350L. I think they BSing me as it is not a luxury car feel. It should be quiet during idle.
is your quiet? can you hear the engine noise while idling?

AndrewTO

Unfortunately with the 4th-gen RX350s, the louder-than-usual engine noise and vibration is pretty common as the engine was changed to include both port and direct injection.

I have both issues, and you may notice the vibration gets worse with the A/C turned on since that adds extra load to the engine. Some of the earlier 4th-gen RX350s had issues with the vaccum pump where it would make a loud knocking sound: https://www.clublexus.com/forums/rx-...e-noise-2.html

TrueOX

OMG, so it is normal or only certain vehicle? can it be fixed? it is Lexus we are talking about, only older cars with little maintenance make a noise like that. my car is barely 9k on it. what a shame to the Lexus brand. I am opening a case with Lexus, maybe they can do something about it.

dibl

I lost my 2015 in an accident and got my 2018 about 3 weeks later, so I had the opportunity to compare them fairly directly. I noticed immediately that the 2018 was louder, when standing beside the front end of the car. The "knocking" noise of the fuel injectors was much more noticeable. Once inside, I only notice the engine noise when accelerating. There's a resonator on the F-Sport that I could swap out for the standard and reduce that a bit, but it doesn't bother me. But they increased the horsepower 45 hp from Gen 3 to Gen 4, so it's not unreasonable to expect a louder motor. As far as vibration, no, I feel no significant vibration in the steering wheel, or elsewhere, and mine has zero rattles, at 32K miles.