Just got a 2011 XC90 3.2 and am new to this engine so there are few sounds that I've been wondering about
I recorded some audio of the engine for about 20 minutes after startup, using a recorder placed on the radiator support. It's sensitive enough to pick up most of the sounds anything in the engine bay is making.
- IMG_8834.jpg (92.35 KiB) Viewed 6 times
Spectrograms (https://en.wikipedia.org/wiki/Spectrogram) are read left to right for time, and up to down for sound frequency, low pitch to high pitch. Color intensity shows the intensity of the sound at that frequency at that time.
Would love some of your thoughts! Thanks!
400hz PCV Whine
1) 400hz, periodic whine, right after startup and phases out after engine warms. Sound appears to be coming from PCV cap, using stethoscope funnel.
400hz, lasts for about one second, off for 0.5 second, gradually phases out as engine warms
High frequency, slowly coming and going 10hz tiktiktik
2) High frequency "pshhhh" sound that also goes "tik-tik-tik" at very close to 10 times a second. Interesting thing is that it starts once engine is warm, and then comes and goes at a pretty stable longer term frequency (on for 2.5 minutes, off for 45 seconds)