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      06-14-2011, 08:37 PM   #1
flash3
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Engine Noise of 28i

So I thought I had read the the engines of the X3's aren't too quiet, even at idle. When I start mine in the mornings, it's not super quiet, and has a slight rattling noise (if you can even call it that - doesn't seem like anything is wrong though).

I have a 28i and wondering if anyone's engine also isn't entirely quiet or does it eventually 'quiet down' over use?
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      06-14-2011, 08:53 PM   #2
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Mine's a 35i, but when warm the idle is quiet enough that with the most minor of ambient noise (grocery parking lot in the 'burbs) I need to sometimes poke back inside and check the tac to see if I turned it off -- a couple times I hadn't! Not at all quiet when cold, though.
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      06-14-2011, 09:13 PM   #3
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I think I might know what you mean by that "rattle," Flash. There seems to be a really pronounced metallic-like rattle especially during cold start. There's also a metal click when you turn off the engine, I'm not sure if it's related, have you heard it with the 28i?
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      06-14-2011, 09:17 PM   #4
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I have yet to hear any metal click but just like a constant metallic rattle in the engine, and nothing that is alarming me, but I just thought the engine would be quieter, for a BMW.

I don't recall listening so much to the engines during my test drives but just wanted to see if others are also not hearing a quiet engine, per say.

I heard it the first time I picked up the car and the dealer said multiple times it was normal in these cars, and I do remember reading somewhere on this very forum too.
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      06-14-2011, 09:24 PM   #5
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This is gonna sound a bit wacky, but when I accelerate from a stop with the driver's window open and near a wall on that same side, it sounds very "rattly" -- metallic, loose bits moving around. Anything like what you're hearing?
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      06-14-2011, 09:40 PM   #6
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Quote:
Originally Posted by Nahoa View Post
This is gonna sound a bit wacky, but when I accelerate from a stop with the driver's window open and near a wall on that same side, it sounds very "rattly" -- metallic, loose bits moving around. Anything like what you're hearing?
I haven't rolled down my windows while driving just yet - usually just have the AC on.

I hear the noise when I first start the engine or when I go check my mail, and have the car still running. It's a very slight rattle sound.
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      06-14-2011, 09:42 PM   #7
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I would said my 28i is very quiet except when cold start.....
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      06-14-2011, 09:43 PM   #8
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Quote:
Originally Posted by Nahoa View Post
This is gonna sound a bit wacky, but when I accelerate from a stop with the driver's window open and near a wall on that same side, it sounds very "rattly" -- metallic, loose bits moving around. Anything like what you're hearing?
Mine didn't have anything like that.....
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      06-15-2011, 08:06 AM   #9
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Quote:
Originally Posted by gareth12468 View Post
I would said my 28i is very quiet except when cold start.....
I can't hear the noise inside and the slight clicking noise is only observed when I am out of the car and the engine is still on.
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      06-15-2011, 08:46 AM   #10
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You're probably hearing the sound of the high pressure injectors. These cars use direct injection into the cylinders (like a diesel) instead of the "older" port injection. This results in about a 10% efficiency gain (better gas mileage) but requires that the fuel injectors operate at a much higher pressure and also open and close much faster (than the "old-style" injectors) because of the critical timing requirements.

The injectors are piezo-electric instead of magnetic and generate a small, audible click when triggered. The sound is not as loud as that of a bad valve lifter, but has much higher frequency components. If you're hearing it, it only means that your high-frequency hearing is still pretty good, or that you're in a garage which is reflecting the sound and making it more noticeable.

The solution is to drive the car harder. The exhaust noise will drown out the injector "clicking".
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      06-15-2011, 09:23 AM   #11
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[QUOTE=Lotus7;9821590]You're probably hearing the sound of the high pressure injectors. /QUOTE]

Not on the 28i.
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      06-15-2011, 11:30 AM   #12
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That's close to what the noise sounds like and mighe be, Lotus.

So I guess I will drive harder but AFTER the break in period
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      06-15-2011, 05:35 PM   #13
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Quote:
Originally Posted by flash3 View Post
That's close to what the noise sounds like and mighe be, Lotus.

So I guess I will drive harder but AFTER the break in period
One more time: No high pressure on the N52, so that's not it.
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      06-16-2011, 09:39 AM   #14
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mine is also quite enough...though I must say, I am not that sensitive to engine sounds in general...
hey you want noise? I've got a 2011 Chevi Equinox! Boy you should try that one! Don't forget earpads though!!!
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      06-16-2011, 10:05 AM   #15
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Quote:
Originally Posted by Lotus7 View Post
You're probably hearing the sound of the high pressure injectors. These cars use direct injection into the cylinders (like a diesel) instead of the "older" port injection. This results in about a 10% efficiency gain (better gas mileage) but requires that the fuel injectors operate at a much higher pressure and also open and close much faster (than the "old-style" injectors) because of the critical timing requirements.

The injectors are piezo-electric instead of magnetic and generate a small, audible click when triggered. The sound is not as loud as that of a bad valve lifter, but has much higher frequency components. If you're hearing it, it only means that your high-frequency hearing is still pretty good, or that you're in a garage which is reflecting the sound and making it more noticeable.

The solution is to drive the car harder. The exhaust noise will drown out the injector "clicking".
Once again a very good explanation!
Thanks Lotus.

So I guess the solution is to go to a few more rock concerts to take care of that high frequency hearing problem.
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      06-16-2011, 03:44 PM   #16
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Quote:
Originally Posted by Harplayr View Post
Once again a very good explanation!
Thanks Lotus.

So I guess the solution is to go to a few more rock concerts to take care of that high frequency hearing problem.
Or just play your iPod at max volume like so many teens and "20-somethings" do these days. I suspect that in 10 or 15 years these kids won't be called the "me" generation any longer, but the "Hearing impared"* generation.

*got to be P.C.
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      06-16-2011, 04:40 PM   #17
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Quote:
Originally Posted by Lotus7 View Post
Or just play your iPod at max volume like so many teens and "20-somethings" do these days. I suspect that in 10 or 15 years these kids won't be called the "me" generation any longer, but the "Hearing impared"* generation.

*got to be P.C.
No, it will become the "Who" me generation, as in "Who me, you talkn' to me". What's funny is that a lot are going to vinyl. Just set my 20 something daughter up with my dad's old Miracord turntable and Bose computer speakers.
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      06-21-2011, 01:20 PM   #18
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I get the rattle on cold start on my 35i as well. It was a bit disconcerting at first, but come to think of it my 2010 335i that I just traded in also had something similar, wasn't really a smooth idler either for that matter. Oh well, I'll get used to it I guess.
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      06-22-2011, 04:11 AM   #19
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so what i have garnered from these forums whether diesel or petrol you will hear rattle in the engine, hmmmmm......
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      10-29-2011, 07:13 AM   #20
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Engine noise

Quote:
Originally Posted by Nahoa View Post
This is gonna sound a bit wacky, but when I accelerate from a stop with the driver's window open and near a wall on that same side, it sounds very "rattly" -- metallic, loose bits moving around. Anything like what you're hearing?

Hi Nahoa,

I think you have hit the nail on the head with your explanation of my problem since day one. When sitting next to a wall it sounds like the motor is actually a diesel... makes me crazy. I brought it to the dealer but of course... no problem. I like the explanation of the direct injection but still not 100% convinced.

Have you brought yours into the dealer?

Thanks!
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      10-29-2011, 07:56 AM   #21
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X3Killer,

See my post (#9) from this thread:

http://x3.xbimmers.com/forums/showth...t=engine+noise

Had these 2 caps installed and that 'diesel' or rattling noise is now gone.

Dave
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