Fizzboy7

One thing I've noticed since I got my IS350 in April is a strange exhaust sound that pops up when I first start driving. Car sits, I start it, and take off.... everything is fine. But then the second time I accelerate, the exhaust makes a strange and faint "vibration" sound for a few moments. Then it's gone by the third acceleration. It almost sounds like the fake, piped in noise, but more of a vibration sound. Seems to be from the mid or rear section of the car. It does not do it any other time, only on the second acceleration of my drive. I thought maybe it was a cold engine thing, but it's been doing it all summer too. My guess is the fake exhaust "generator" has a glitch or needs to warm up a bit before acting right? Have no idea beyond that. It's not loud and it's not a big deal, but something I do notice with nearly every drive.
Thanks for any info...

arentz07

This sounds like a resonance with something in the interior or exhaust. I had a similar thing crop up from time to time on my IS 350 at low RPM after cold starts.

You can simply disable the ASC by turning it all the way down until it "clicks" into the off position if you want to eliminate that as the culprit.

Fizzboy7

Interesting, thanks for that. I did however already test it with the system clicked off. Still made the vibration sound. Will try that again though, just to be sure.

Fizzboy7

Revisiting the thread. The vibration sound has become more, even with the system turned off. It's happening under light acceleration, after the engine upshifts and is lugging (especially on inclines). Can be from 2 to 3, 3 to 4, or 4 to 5. Seems to happen several times per day, but not during every acceleration. I have yet to take it in to be looked at, but I'm coming up on my 10k service soon.