What is this N20 engine part?

T

TitanTim

Elite
Hi all,
I have the Zed booked in for 2 weeks today, (earliest I could get it looked at if I wanted a courtesy car :tumbleweed: ) to investigate this blooming engine whine when cold. Its kinda irritating as fairly loud and IMHO not right. I've had a good listen when its making the noise and have ruled out, drive belt, pulleys, alternator, air con compressor as the whine is there with air con switched off. Definitely not transmission. The Whine increases and decreases with revs but hardly detectable once on the move. Anyways the noise seems to be coming from the nearside of the engine specifically around the area I've circled on the engine pic below. Does anyone know what that part is? I think the turbo is on the otherside lower down. As the engine warms up the noise slowly subsides and there is just a hint of whine at idle.

I've been doing a fair bit of googling and found a couple of road tests of the Z4 with the N20 engine where it mentions it does whine but that doesn't seem to be the case with most owners on here.



http://news.drive.com.au/drive/motor-news/driven-bmw-z4-fourcylinder-models-20111221-1p4kd.html

http://www.carsguide.com.au/news-and-reviews/car-reviews-road-tests/new_bmw_z4_review

I'm just trying to establish whether some engine whine is the norm on this engine and that mine just happens to be a bit more noisier. If thats the case the dealer may just say its normal :cry:

The zed is performing fine, no hesitation or problems, just noisy when cold :(

Cheers,

Tim.
 
Hi Tim,

Probably nothing to do with your engine but on my z3 I have secondary air pump which forces air into the engine when cold (to keep emissions down) and used to pack up every six months or so making whining sounds. This only happened when the car was cold. Not sure if they still use those.
 
philabbo said:
Hi Tim,

Probably nothing to do with your engine but on my z3 I have secondary air pump which forces air into the engine when cold (to keep emissions down) and used to pack up every six months or so making whining sounds. This only happened when the car was cold. Not sure if they still use those.
Click to expand...

Cheers for that, I was wandering if it was some sort of air pump but no idea really :oops: I have a Z3 as well and it has never whined or made unusual noises, in fact its positively smooth and quiet and is 11 years older than the Z4 :( and thats with a 4cyl engine :roll:

Tim.
 
IIRC it changes the length of the air inlet for optimum torque/HP at different revs. I'm sure someone will come along and correct me. There have been a few threads on here about lose mounting pins on E85/E86 engines.

I know we're on different engines, but when mine is warming up, various things change in the engine and for a couple of minutes it sounds really throaty, then it settles down into a really smooth idle.
 
Looks like this part...
http://www.realoem.com/bmw/showparts.do?model=LL32&mospid=53585&btnr=13_1418&hg=13&fg=15
367.png
 
Stuart Truman said:
IIRC it changes the length of the air inlet for optimum torque/HP at different revs. I'm sure someone will come along and correct me. There have been a few threads on here about lose mounting pins on E85/E86 engines.

I know we're on different engines, but when mine is warming up, various things change in the engine and for a couple of minutes it sounds really throaty, then it settles down into a really smooth idle.
Click to expand...

Cheers Stuart, I think you may be correct as just been having a read on Bimmerforum, I can't be 100% sure the noise is coming from this item on the engine but would be useful to identify what it is so I can tell the dealer :)

Tim.
 
TitanTim said:
2nd question, would that necessarily whine :?

Tim.
Click to expand...


No it wouldn't. Our cars are drive by wire. The throttle butterfly is controlled electronically. That's why there is that big motor on the side.

The N20 is a valvetronic motor. Most of the time, engine output is controlled by valve lift. Once the engine is started, the throttle butterfly runs wide open. It is there only as a backup in case the valvetronic mechanism fails.
 
Besides the air pump for emmissions, valvetronic engines also have an electric vacuum pump, as there is hardly any manifold vacuum available. Sounds just like a Hoover, only quieter.
 
It's a throttle plate air valve:

Source http://wiki.answers.com/Q/What_is_valvetronic

“that the throttle plate is not removed, but rather defaults to a fully open position once the engine is running. The throttle will partially close when the engine is first started, to create the initial vacuum needed for certain engine functions, such as emissions control.”
 
Thanks for the replies, I'm guessing this isn't the part that could be causing the noise then, I'm starting to think its the turbo :( as suggested by our american friends on ZPost, i.e. it whines as its a Twin Scroll? but is that normal?

I've read some owners having problems with noisy turbos on X1s 125i and 328is

Could it be a bad turbo? duff bearing? hoping not as I doubt BMW will change it unless it actually fails.

Tim.
 
Fuel pump noise has been mentioned on here before I get it now and again but just ignore it now :poke:
 
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