BMW 325i May 2010 E90 3.0 litre - BMW 325i (E90 3.0) - noisy at idle

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Tue 26 Apr 2011 23:17
BMW 325i May 2010 E90 3.0 litre - BMW 325i (E90 3.0) - noisy at idle - peterb

Hello all. Have been away a while but am back with a problem new car.

After 8 years of driving Lexuses (IS200 / IS250) last year I ordered 325i (3.0 litre).

Although in many ways a better drive than the Lexuses I'm really struggling with just how noisy it is at idle and low revs - especially (but not only) when cold. It sounds like a diesel and I HATE the sound of diesel engines.

It went to the dealer a few months ago after the amber engine warning light came on and they replaced the ignition coil and spark plugs. It was OK for a while but has since got noisier and noisier. I took it back to my local dealer a week ago and they said the coil was OK but gave it a software upgrade which has made no difference. Not sure if this is relevant, but as well as being noisy the fuel consumption is pretty poor - I realise any 3.0 litre petrol 6 pot will have a bit of a drink problem but this averages less than 20 mpg around town (my 6 cyl IS250 was more like 25).

Any advice on the noisy idle? Surely a fairly expensive 6 cylinder petrol engine should be quiet? It's a company car so I can't even get rid....

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Wed 27 Apr 2011 00:12
BMW 325i May 2010 E90 3.0 litre - BMW 325i (E90 3.0) - noisy at idle - unthrottled

325i-shouldn't that be a 2.5 litre rather than a 3.0?

I think the engine is Direct injection. Direct injection is noisy-in fact most of the noise from modern common rail diesels is the high pressure pump-not pre-mixed combustion knock. The pump on Gasoline Direct Injection engines can easily sound like a diesel at idle. Maybe this is the noise-in which case it won't go away, I'm afraid. If the Lexi you you previously drove were equiped with low pressure port injection, they will be quieter at idle.

That's progress for you!

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Wed 27 Apr 2011 12:31
BMW 325i May 2010 E90 3.0 litre - BMW 325i (E90 3.0) - noisy at idle - peterb

Thanks unthrottled.

It's a 3.0. BMW and Merc labelling is odd these days. BMW give you more than your think (325 is 3.0, 318 is 2.0) and Merc give you less (C250 is 1.8 turbo)!

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Wed 27 Apr 2011 12:43
BMW 325i May 2010 E90 3.0 litre - BMW 325i (E90 3.0) - noisy at idle - unthrottled

I knew the 335D and 340D were all 3 litre engines, but I thought BMW still made a 2.5 litre. Silly idea, I'll just call mine a V8 (it's only got 4 cylinders, but if BMW can play fast with the numbers...)

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Tue 22 Nov 2011 01:28
BMW 325i May 2010 E90 3.0 litre - BMW 325i (E90 3.0) - noisy at idle - larrylej

Hi, I have a 2008 3.0 litre 325i M sport coupe with 19inch RFTs, I'm averaging only between 17-18mpg, driving mainly to work and back (2.5 miles each journey). Quite a lot of start./stop, and short cuts through neighbourhood roads. I'm wondering is this normal? However, on a long run in a motorway, the car's average mpg is between 38 to 40mpg.

I'm thinking of checking the car out a local dealer, as it is still under the approved car warranty. What would you advise?

Thanks

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