Car has about 600 miles on it. Yesterday I put on new non run flats (Pirelli AS Plus 3... had the Plus II on a BMW and loved them) and driving home I noticed a very faint, muted, chirp or squeak rattle noise during extremely light throttle application. If I let off the gas the noise immediately stops.

Driving say 20mph, and just lightly press gas to get the most leisurely acceleration possible and I can get that chirp. I can replicated most times but other times it seems to remain silent. It must be on quiet, smooth blacktop otherwise it is nearly impossible to hear.

I saw someone on the GS forum mentioning they've had something similar and it may have been an intake. Can't seem to dig up anything elsewhere on the net.

My thing is is there any possibility the new tires or the tire install could create this noise? Seems impossible to me since I would expect any tire noise would be constant and have nothing to do with applying a bit of throttle. It just seems awfully coincidental that I noticed it upon driving back from the tire shop. With that said I was carefully listening for any weird noises, the tires are noticeably quieter than the run-flat bridgestones... so maybe I just couldn't hear the chirp before? The noise is not loud.

It was about 60F yesterday, first "warm" day since having the car here. Temp related?

Could it be the turbo? I don't know exactly how they work but a bit of throttle = turbo spools a bit and makes a squeaking or chirp noise?

Engine knock??

VVT or timing chain?

I'm debating whether to ask the tire shop to dismount and check everything again... I know sometimes brake shields can get slightly bent or something but again I feel that kind of noise would be constant and not only when applying throttle... but I always hate having the tire shops work on my cars. I try to keep my interactions there to a minimum (though I've never had a bad experience there)

Will keep troubleshooting but curious if any other LS owners have noticed this?

 

Blinker fluid reservoir is low for certain.

 

Ha that's what my mechanic said!

 

OH! I has idea. Well maybe. When I had my 2002 LS430 with the 16" chrome wheels I had a sound after new tires/balance. Turned out the shop had used thick wheel weights that were ever-so-slightly rubbing against my brake caliper, and I could only hear it at parking lot speeds. Not 100% sure your wheel size, or how big the brake calipers on a LS500 are but get a flashlight and check the inside surface of your wheel to see if the wheel weights are rubbing. I know in the 2002 Lexus manual specifically says stick-on weights for the inward wheel correction then they were supposed to use clip-on style weights for the outside face correction. Of course, this generic tire shop (or most anyone) just use stick on weights to avoid damaging the wheels. I think I took the wheel off myself and bought thinner wheel weights.

Edit: probably not anything more than wheels rubbing on something. I wouldn't worry about anything mechanically. Just start with what was changed/worked on then work your way to other avenues.

 

Appreciate the feedback. I will take a look at wheel weights.

Thing is it makes the sound only when on the throttle. Then it immediately stops as soon as you let off the gas. I would think anything tire related would be constant, regardless of throttle.

Had the car in the other week. They thought it was the hood-popping explosive pedestrian air bag pins. It seemed to be gone at least after I picked it up but it’s back again and unfortunately exactly the same. The tech said he checked suspension and tires and all that. Removed the wheels to do inspection.

It is beyond bizarre. I suspect a coincidence with the new tires. Any reason it could be in the wheel/tire? Like a loose TPMS sensor or something? Should I suggest demounting and remounting the tires?

Will keep folks posted as we work through this.

I will add my dealership has been excellent. Obviously would like it fixed and I know it’s a tough one but the service and willingness to keep tackling has been really excellent.

 

I know this isn't a lively thread but just wanted to provide an update. Lexus flew in a regional master tech to look at the car. Could not find the cause. They actually took all the wheels and tires off my car and put on a set from a brand new LS500 on the lot and it still was chirping. So appears not tire or wheel related. Acknowledge the sound exists and the car has been in service I think 3 times now for probably 4-5 days total with them but they just can't find it. We all test drove another brand new LS500 as well and it was silent. So something with my car specifically. I can certainly imagine it is hard to find being it only does it under light throttle application. Revving the engine stationary sounds totally normal. Finding a sound that only occurs when moving I imagine is really hard.

Saga continues. Its unfortunately very disappointing in a brand new beautiful expensive car to hear chirp-chirp-chirp as you pull away from stoplights or just cruise along at 30mph.

 

Brake backing plate

 

You know... I was wondering this possibly. I may have a look. Thank you. I did check the brake shields today.

Otherwise I spent all afternoon driving around the neighborhood like an idiot. But I did discover that the noise almost goes away when turning right, and gets louder turning left.

It also turns out that turning left while coasting or in neutal it also chirps. So thinking it was light throttle or 1500 rpm is not correct. I couldn't determine if applying brakes during that left turn would stop the noise or not. It may have but I'm not sure. Was hoping if I can determine application of brakes eliminates it, then I might be able to narrow it down to something in the brakes.

My only other thoughts could be wheel bearing? Any bad bearing I've ever heard was a grinding noise not a chirp. I'll have to research bushings, tie rods etc. Doesn't do it if I bounce the suspension and also doesn't make noise if the car is parked and I push it forward <-> backwards.

Would such a chirp only when turning left indicate anything with belts or alternator bearings or anything like that? Just a little lateral force from the turn makes it worse?

Will continue to update, even though I might be the only LS person with this problem Never know if it might help someone down the road...

 

Wanted to follow up here... I finally figured it out!

I couldn't take it anymore, had more or less narrowed it down to somewhere in engine compartment or wheel well on front passenger side. Just decided I was gonna dedicate a few hours and really dig through everything. I checked all the belts with water, removed engine cover and just started tapping and pulling and moving basically anything I could get my hands on to see if anything made a similar noise.

After maybe 45 minutes.... I finally found it!

The passenger strut tower brace was rubbing on a plastic encasement for a wiring harness. It was clear as day. The harness didn't move much at all but when you pushed it back and forth on the strut brace you'd get a very high-pitched chirping rubbing noise.

Pushed the harness away from the brace as best I could.... silence! It came back after some time but took to dealer and they added a rattle kit or something to that plastic harness (felt?) and I've not had a noise since.

I suspect that it was only most noticeable under light acceleration or left turns because the car slightly torques the engine and harness or flexed the strut tower brace just enough that the two parts would touch with some force. The gap was just that small between the parts.

Anyway, for internet posterity and in case anyone else finds their LS chirping, I hope this might help someone.

 

Nice work. It feels great to solve a nagging problem.

 

Wow such a small thing and big annoyance, glad you found out what it was.

At least the blinker fluid reservoir was not low LOL

 

@Jerome10 , THIS IS WHAT I READ THE FORUMS FOR!!! Thank you for posting a follow-up. Now you are smarter than that Lexus master tech. You'll be able to fix anything now!!