Change in engine tone?

[Mr Olympik]

Hi,

I was sat in my car with the engine idling and plugged in with my OBD11. I didn't change any settings but was just browsing when I heard and felt the engines tone change and the car seemed to run not as smoothly. Climate control was fully off.

Does anyone have any ideas what it could be?

PS: Car came back from stealers yesterday after a major service.

 

[jds_sg]

Active regen? Was the cooling fan going and the idle speed increased?

 

[Mr Olympik]

Active regen? Was the cooling fan going and the idle speed increased?

I didn't notice. From what I could tell the idle speed stayed the same, it went back to normal as soon as I engaged a gear.

 

[A4Ultra]

Taken for a drive since? Notice anything then?

Hopefully nothing but you never know with the stealers

 

[Mr Olympik]

Seems ok on driving. Might have to try and replicate the fault again.


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[cuke2u]

Even though the CC might be set to off on the controls it will still be on so could be the compressor..

 

[MOA4B9]

My car does that, if you keep it idling long enough it will at some point change the tone. It sounds like change in revs or if someone changed gear. I don't think it is an issue, just what it's ment to do. Maybe it's dependent on engine temperature or demand for electricity.

 

[cuke2u]

Could be any of the electric coolant pumps. As it's only a change in note I wouldn't be unduly concerned...