81DOB

Hi. My car is an 2013 GS350 FSport. I am experiencing an unusual noise over 5000 rpm to redline that sounds similar to pre igniting “pinging” but it’s definitely not becuase when I throttle off its stays until it drops below approx 5000 rpm.

the noise is like a fluttering mechanical noise but doesn’t sound like a critical engine noise.

I took it to Lexus becuase it is still under a used warranty. The tech cam for a drive with me and said that he hadn’t heard it before. They check over the car hooked up diagnostics. To their credit they tried really hard to diagnose but said that they didn’t want to keep testing the car at high rPM as they felt it’s nothing to be concerned about.

has anyone experienced anything like it? I use 5 30 full synth oil. The car runs really strong. The noise is distinctly on the drivers side (I’m on Aus right hand drive). My thoughts are possible an issue with the sound generator, the right hand pre cat or the high pressure fuel pump?

any advise would be great.

KIS350

That’s a first for me…”sound generator”….I feel like I’m being punked. Lol. What is a sound generator? In my car it’s a Mark Levinson 5.1 surround sound system, but I don’t believe that’s your issue.

Did you solve this problem?

KIS350

Is your engine a 2gr-fse? And the problem consistently is over 5000 rpms? Not any other rpms? Is it a rattle? like the cold start rattle on these engines? Does it go away immediately upon braking or deceleration?

81DOB

Yes it’s a 2GR FSE. Not sure if your joking about the sound generator or not? But all 4th Gen GS350s have a sound generator of the intake manifold that essentially generate engine sound sound after about 3500rpm. It’s just a small plastic piece with a diaphragm inside.

no engine rattles at any other time than explained in the post. The sound is very hard to describe. It’s not always the same intensity lending me to thinking it’s not mechanical but rather some sort of vacuum or exhaust leak. As the post states even the Lexus tech stated he is not concerned by it but I just really want to narrow it down and understand where it’s comming from.

it does remain on deceleration u til the rpm drops to approx 5k.

KIS350

I don’t blame you for wanting to at least narrow it down and find it. Have you revved the engine to 5000 rpms while listening in the engine compartment. At the very least were you able to determine if it’s doing it while parked as well as while the car is moving?
I think you’re probably on the right track with exhaust and vacuum, or even an intake leak. It could be ac pump, a piece of serpentine belt missing or worn…could be anything really. Sorry, that isn’t much help.
“Fluttering” makes me think of valves. Not necessarily valves them selves but like you said a vacuum leak/exhaust leak. I would think with exhaust you’d hear it all the time on some level, even if not as loud.
See if you get the sound to appear in park while under the hood, if you feel safe doing so, and try to find roughly where it’s coming from, the middle, both sides, underneath…this will greatly help you.

edit: sorry I just realized you said drivers side. Good possibility it is your high pressure fuel pump. It’s close to the fire wall and they definitely do get pretty loud fluttering sounds. Mine is 2nd gen and that pumps sound is noticeable from the cockpit. And I’m driving on the other side of it.

81DOB

Hey KIS350. Thanks for the feedback. I Revved it up multiple times in the garage past 5000 rpm and nothing. Tried with AC on and Off. really strange it doesn’t do it at a stand still?

KIS350

Ok, so it’s narrowed down to engine speed, not vehicle speed, doesn’t do it park, only in drive. My mind goes immediately to flex plate (flywheel) or torque converter. It’s the only things I can think of that is affected by both the vehicle moving and the engine speed that is right in front of the firewall. If your flywheel is cracked or malfunctioning it can vibrate at certain rpms. The torque converter can make sounds when deteriorating too, again at varying rpms depending on vehicle and type of problem. I’ve never had either go in a car but I know they can make some crazy sounds when they’re at the end of their life or have breakage occurring. They’re both right there in front (just below mid-level) of the firewall. It’s my first thought anyway. Hard to know really without hearing it. I would still think you’d hear something, maybe, when not driving…

KIS350

Any exhaust or vacuum sound, that I can think of, would make the sound regardless of driving or parking and is 100% responsive to rpms. The flex-plate and torque converter connect to both moving transmission parts and crankshaft so it would make the most sense to me.

81DOB

So tried again while parked and it made the noise this time.

through testing I have since learnt that the hotter the outside ambient temp and the longer I drive it (presumingly because the engine bay gets hotter?) it seeems to be less noticeable and sometimes not even there?

just To totally rule out pinging I added some +6 octane boost to premium 98 octane fuel and that made no difference. I just had to rule it out because it sounds surprising similar sometimes but higher frequency in relation to engine speed. It’s making me lean towards the high pressure fuel pump?

KIS350

Good idea with your testing. Do you drive this car daily? Have you noticed any difference with any fuel or oil consumption? Any engine codes come up yet? This is definitely a strange one. Is there a way you could post an audio clip of the sound you're hearing? Even if it was on youtube or something. I just replaced my engine over last weekend and all week I was listening out for a sound that could be related to your issue. There are a lot of sounds in this car lol. Would be nice, even for my own curiosity, to hear what you're hearing. I don't believe you have the only Lexus making this sound... So even if it's a bit of trailblazing to resolving this issue, I feel it's worth it.
I won't quite rule out torque converter or flex plate yet, but it does sound like it's something else. I'm going to look into this "sound generator" in the meantime. Also, I think you're on the most probable solution with the high-pressure fuel pump. It definitely can be a noisy sound but does very car to car. I'm going to get my someone to drive my car and I'll sit in the passenger side (same side you as an Australian driver sit) and get up over 5000 rpms and see if I can hear anything like what you describe.

Like you said; if nothing is noticeable in performance then nothing to worry about, however, it would be great to at least know what it was.

KIS350

One other thing I just thought of is your master cylinder is also on your firewall on your side and runs on vacuum from your intake...One potential thought to consider. Just trying to think of things that are around there that could make sounds. Any notice in braking?