Geo1688

I have less than 2000 miles on the odometer and I recently noticed that my car's engine makes an intermittent whine/whistle while in idle. Is this normal for a turbo engine? Any thoughts appreciated.

Geo1688

To clarify, it almost sounds like a beeping sound coming from the engine compartment.

BMWBig6

I don't hear anything like that with mine with the windows up or down at idle. You can hear this noise from your driver's seat? Or from outside the car with the engine idling?

ThePiombino

That would be the turbo kicking in...

ItsDubC

I too get that sometimes, but mine sounds more like a buzzing sound. I tend to notice it when I'm stopped at a light after having driven at least 5 miles or so. The engine's already warmed up and the RPMs are steady at about 800, so I don't think it's the turbo. I was going to wait until my 1st service to ask the dealer about it but it'd be nice to get some insight before that time.

BMWBig6

Mine always kicks in hard at idle too...

Mobilehavoc

Maybe the OP likes to rev the engine every time he starts?!

Geo1688

I just hear the noise when I am outside the car to get the mail after the engine has warmed up. The b&o is usually on a little too loud while I am in the car. I was gonna ask the dealer at my first service but wanted to find out if this is something I should be concerned with.

frosty1

air pump?

Moviela

Turbochargers do not "kick in" at idle. When they are spinning at or near 100,000 rpm they have a distinctive whine, and the pitch of the whine varies with engine speed.

At idle the turbine is just spinning in the airflow from the exhaust. It is not turning fast enough to produce any meaningful amount of compressed air. You will not hear any whine at all. A manifold pressure gage would display vacuum.

As you increase engine speed, heat begins to flow out of the engine. The heat is what is converted to mechanical energy in the turbo. It is not the air coming out of the engine that compresses the air. The heat causes the turbine to accelerate. When the shaft reaches operating speed, intake air is compressed and sent to the engine intake. The compressed air has more oxygen than a similar volume of atmospheric air. Since there is more oxygen, more fuel can be spritzed, and thus more power. Turbo lag is the moment between when the engine speeds up until the compressed air is available in the intake. A lot of research has gone into reducing turbo lag. Electronics, waste gates, intelligent plumbing, inter-coolers, and the design of the turbine blades themselves have made turbochargers on gas engines more desirable than the system on grandpa's Turbo-diesel.

The noise you are probably hearing at idle are the electric cooling fans.