docmarioce

Hi all. I have a 2011 LS 460 with 28K miles in very good shape although there is a noise most audible when I am in a stop sign that dissapears when I shift the transmission to "P". The noise is like a tackat tackat tackat tackat . I took the car to the dealer and the service advisor claims is normal. Is it or my car is defective?

Best,

Mario

islandbeef

If the service guy tells you it's normal without inspecting or putting your car on the rack and actually "looking", he's full of BS and is just lazy. Talk to another service person at the same dealership OR just take it somewhere else and get a second opinion.

Don't get chumped by these guys.

hfahmy

This is the idle noise that is discussed extensively on this forum. When you shift to P, RPM goes up and noise goes away. similar can be achieved by turning on AC or light.

If this is what you are referring to, I would leave it alone.

docmarioce

Yes, although I haven't checked with the AC or light. Sometimes when the car is hot of running for a while the noise is less audible. The service adviser claims is the Pump (don't knowif the gas pump or the transmission pump since I know "NOTHING" about mechanics). He also mentioned something about the valves that open and close when the car is changed from "D" to "P" and vice versa. Any further clarification would be great

Rhambler

High-pressure fuel pump and it's normal. Any car, from any brand, that uses these direct-injection, super, super high-pressure fuel pumps exhibit these noises. The amount of pressure required to pump fuel in for a direct-injected is enormous, hundreds and hundreds of PSI and that's the sound you hear.

Some cars and brands are louder than others, but that's the price we pay for engine "innovation." Our car is actually relatively quiet. I had a 2015 Acura MDX loaner for my previous car and it sounded like a gigantic racket under the hood. The Audi I test drove was loud as well.

Frankly, I miss the good old, simple and very long-lived PFI engines. Anything that pushes fluids at that pressure has drawbacks, notably noise and longevity.

docmarioce

Thanks. I feel better now although sometimes is annoying I still love my superCar.

Rhambler

If you're curious about the relativity of what I was talking about, here's a link to Acura's MDX, which I was given as a loaner last year.

http://www.torquenews.com/1574/acura...xplained-video

It sounded like a choir of castanets all happily clanging away. It was loud inside and even louder standing next to it outside. I was actually embarrassed at stop lights with people next me with their windows down. There's a YouTube video from the article at the end and yes, THIS is considered normal according to Honda.

In any case, I hate DI engines. I could care less fuel economy, lol.

Tec80

DI is pretty awesome for power as well as fuel efficiency. The additional charge cooling provided by spraying fuel directly into the cylinder allows 1960s-style high compression ratios, 11.5-13:1. The drawback is that intake valves no longer receive a cleaning spray of fuel, so many DI engines are now suffering from intake valve deposits. Lexus eliminated this problem on our cars by using BOTH DI and port injectors (the D4-S system). DI cars also have higher soot emissions, to the point that particulate filters are under consideration (similar to the DPF most current Diesel engines use to meet Tier 4/Stage V emission regulations).