Engine Vibration

[C Mclean]

Got a really annoying mid range vibration coming thru the steering wheel and pedals. Happens when the revs are between 1150 and 1200 at any road speed and you can slightly hear a droning noise as well. Increase the engine speed and it settles down. Drop the power requirement so the engine stops and the vibration stops. It’s mostly noticeable cruising around 30 - 50mph on a light throttle. 

Not being caused by the wheels or tyres as it’s not road speed dependant.

Though it might be power steering pump, but crossed that out as the steering assistance is electric.

AC compressor switched on or off makes no difference.

Checked for fault codes, none found

Mentioned it when the car was serviced a few month back, no fault noted

Had it into Lexus a few days ago and the Tech could notice it slightly, but thought it could be happening just as the engine was powering down/ stopping charging the batteries. 

I have found a way to replicate the vibration, so I’ll check with Lexus again, but would be interested if anyone else has noticed anything with their car.

With the engine already warmed up. Car stopped, gear lever into drive, apply parking brake, slowly press accelerator until revs reach 1150 to 1200 and see if anything can be felt thru the wheel and pedals. Please note the the car may try to creep forward very slightly and the back end will drop an inch or two.

Thanks in advance for any input.

 

[Gliderpilot]

If the car is a hybrid then the A/C comp is also electric.

[stringbender]

Hi Colin,

I had a similar problem with a 17 plate Premier and posted here about vibration and judder. After 14 years of near serene driving in my series 2 (2005) RX300 this nearly drove me mad. Unlike you I failed to replicate it and Lexus said it wasn't there at all. I could feel the vibrations coming up through the driver's seat and so spent a huge amount of time underneath the car. The exhaust is suspended by 6 rubber hangers. 4 of them allow considerable movement back to front but the other 2 virtually prevent it and only offer a few millimetres of moment. I felt as though the engine vibration was coming into the cabin when the engine was pushing the exhaust silencer tight against the holders. I even bought "fire rope" and was going to remove the rubber mounts and use the rope ( with a metal wire for safety !) as a test. Rope never got used as I gave up and sold it. 

I drove about 6 RX450h's whilst mine was in dock and only 1 was as smooth as my '05. The others had a bit of what I was complaining about but mine was terrible. My new (69) one is not as smooth as I'd like but it is bearable. Otherwise the car is amazing. I also wondered if the car had faulty engine mounts but never found out. I was just surprised that a so called luxury brand could produce a product that was capable of vibrating the driver so much.

I'd be interested if you ever find out what the cause is.

Alan

 

[C Mclean]

Short update on this problem.

Took it into Lexus and gave them a short test drive/demonstration. They weren’t convinced there was much of a problem and I also had a run in another RX to compare things, not much difference so left it at that. Also asked if there was a “maintenance mode” so you could rev the engine without it being in gear and was told no.

Still annoying the poop out of me so I started trawling the internet for any info on this apart from Stringbender’s report and surprise surprise. There is a maintenance mode, but the throttle response is pretty poor so it’s difficult to keep the revs stable. Also in the USA there are some reports of vibration and resonance on some RX models, but mainly 350 models. Anyway I’ve found there has been exhaust dampers fitted to some older models.

Toyota Part No:

17581-31010

Damper, Exhaust Pipe

 

I also discovered that if you start the car, engine warmed up, select drive then reapply the parking brake, you can increase the revs to the point of vibration. 
 

Back to Lexus again and spoke to their Master Technician and showed him the “maintenance mode” which he did know about, demonstrated the problem by increasing revs while in gear and parking brake on, but he didn’t think it was a significant problem. Tried the same thing with another RX and it wasn’t as bad as mine. Mentioned about the Exhaust Dampers and he did say they were fitted to some older models, but they did have a tendency to cause cracks in the exhaust pipes as the cars got older and the pipes got rustier.

 

Next plan of action is to source a couple of these dampers and see how it goes, if no real difference it’ll be bye bye RX and see what else is available.

[stringbender]

This all sounds so similar to the problems I experienced with my first 4Rx. I remember getting a nail and taking the car to my "tyre man" He was intrigued by the car's menus as he sat in the driver's seat. I had forgotten to turn the engine to off and when the engine started itself he was appalled by the noise and the vibration and said this cannot be right. He also mentioned exhaust dampers but I didn't know what he was talking about.

Lexus did eventually change the exhaust system but, although it improved things, it didn't solve the problem. The only solution came by saying bye bye. My new car is better but still has some of the annoying characteristics. Maybe it doesn't affect other drivers but I still think Lexus has a built in problem here and that a prestige brand should have spent more effort ensuring that the engine's vibrations are kept out of the cabin. I too will be seeing what else is available when the time comes.

Alan 

[C Mclean]

Eventually got the exhaust dampers fitted, now just need to see if they make any difference.

 

[stringbender]

I hope this works Colin. If it does could you let us know exactly what you've used and how you did it. I feel mine has deteriorated in the last 500 miles which is very disappointing.

Alan

[C Mclean]

👍

[Keeling54]

I have this on my Rx400h, my wife noticed it just after the Cat was stolen and I installed a replacement non oem part.

It bugs me slightly but I don't drive the car often enough to really worry about it.  

[C Mclean]

Well I’ve tried moving the clamps and dampers from the front of the main exhaust pipe, to the centre and then to the rear just before the silencer. The only result was a change in the vibration frequency, seemed to lower it a bit, but it still happened around the 1150-1200rpm mark. So it looks as though I’ll have to live with it until it’s time to change to something else. 

[stringbender]

It's a shame the dampers haven't solved the problem. I did wonder if  they may help  transmit vibrations into the body and maybe they did. I still think that the exhaust hangers are worth looking at as the cause ( see earlier post ). When Lexus Bristol changed my exhaust system they removed the original 18mm thick hangers and replaced them with 28mm thick new ones. They denied doing this but I remain certain that they did. Quite why they'd feel the need to deny it is beyond me. Anyway the problem became worse! I think that was because the allowable movement back to front was now 5mm less each way and the rubber was being crushed either against the end stop one way or the metal hanger bolted to the body. the other. It still baffles me that of the 6 rubber hangers 4 allow considerable fore/aft movement whilst the other 2 practically prevent it.

Such a shame for such a nice car.

[Omar6575]

Colin,

 

how close di you place the dampers to the silencer?