anniversar

As the original poster I would like to make a few comments on what appears to be a controversial thread.

My 2010 LS460L AWD 47,000 miles has the ticking noise to the extent that I can easily hear it at idle with the AC fan on low. It is very obvious and not a subtle noise at all. I am originally from the UK and back in the 70's our cars had valve clearances that needed manual adjustment every so often. The noise in the lexus is similar to the "tappet" noise I used to have to adjust out back in the day. Three Lexus dealers advise it is normal for the design of the engine.

In my limited exposure to other current luxury cars, the Lexus noise is not typical for a high end DI engine based car, but abnormal. I recently test drove a BMW750, Audi A8, Infiniti Q70, Jaguar XJ and a Mercedes CLS. All of these are were much quieter at idle but the Lexus was better at speed. I also drove a SWB new LS460 and could here the tapping noise at idle in this. It was a little quieter than mine but not as quiet as the rival vehicles I evaluated.

While I understand the noise is related to the direct injection system (the engineering paper I attached to my original post discussed this), it does seem possible to silence the noise in this type of engine design as otherwise why would the 5 other makes I drove have much less noise. Also the engineering paper suggests one possible method that could be retrofitted. When the Wisconsin weather gets warmer, I am going to remove the engine cover and so how possible this might be.

For those of you who may not have opened the attached paper, I am pasting the abstract from the paper which refers to the isolation of the fuel rail as a possible remedy. It is worth reading the whole paper to get the full details.

Abstract

Noise Reduction in Gasoline DI Engines by Isolating the Fuel System

Atsushi Watanabe1 Atsushi Hohkita2, Masahiro Soma2, Hiroaki Saeki2, Tohru Ishikawa2 Jonathan Borg3
1 Hitachi, Ltd., Mechanical Engineering Research Laboratory,
Horiguchi 832-2, Hitachinaka, Ibaraki, Japan
e-mail: atsushi.watanabe.gp@hitachi.com
2 Hitachi Automotive Systems, Ltd.
3 Hitachi Europe, GmbH, Automotive R&D Laboratory


We developed a novel method for reducing the noise level associated with the high-pressure fuel system in gasoline direct-injection (DI) engines. We focused on the noise level at idle running speed, because the idle state engine noise is the only noise source to the driver. To reduce the noise level of the idling engine,we focused on the vibration transmission path from the high-pressure fuel system to the cylinder head which results in noise radiation from the engine block. The dominant vibration source of the high-pressure fuel system was fuel pulsation from the high-pressure fuel pump and activation noise of the solenoid-drive
injector. To reduce the vibration transmission from the high-pressure fuel system to the cylinder head, the fuel rail and the injector were isolated from the cylinder head by avoiding metal-to-metal contact. This isolation method eliminates the transmission path from the vibration source (high-pressure fuel system) to the radiation source (cylinder head). Mid-frequency noise in the 1 to 3 kHz range is reduced by 5 dB by isolating the fuel rail from the cylinder head with rubber-like damping material. Moreover, high-frequency injector ticking noise above 5 kHz is reduced by 3 dB by suspending the injector from the fuel rail. This method drastically reduces noise radiation associated with high-pressure fuel system in a gasoline DI
engine.

tbilisi79

I can barely tell if the car is running at all from outside. There is a slight tick if you stand right by front of the car. But feom inside I can not hear anything at all. Windows open or closed. Motor is not as smooth at idle as the 430gs I had.

subsurf

I was just told by the Lexus technician that the ticking is due to the fuel injectors. Anyone else hear that?

BT3100

I have a high pressure fuel pump on the EFI motor on my boat.
It's a new motor 2014. The retro fitter (GM makes all blocks and companies retro fit them) surrounded the high pressure fuel pump in case and ran coolant around the pump.
The literature stated that this helped in two areas. It reduced the temp of the pump and dampened the ticking sound of the pump.

roadfrog

Ummm....did you read the thread??