Motoring Discussion > BMW 3-Series E90 - BMW 440i 2017 - Exhaust tips Miscellaneous
Thread Author: Mr Moo Replies: 10
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New Tue 6 Nov 18 21:00 
 BMW 3-Series E90 - BMW 440i 2017 - Exhaust tips - Mr Moo
Sitting at a red light this evening, I found myself behind a 2017 BMW 440i. The car had two exhaust pipes, one on the left and t'other on the right.

Given the potent engine in the car, I assume that both pipes are used for exhaust purposes, rather than one being for show. However, one pipe was crystal clean, whilst the other was pretty black. Looked like a Euro 4 (or earlier) diesel exhaust.

Can't imagine that one pipe was just for show, so why was one crystal clean and the other filthy? For what would be a Euro 6 petrol, I was surprised how grubby it was!
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New Tue 6 Nov 18 21:10 
 BMW 3-Series E90 - BMW 440i 2017 - Exhaust tips - PeterS
If it’s the same system as my 235i operates it’ll be because there’s an electronically controlled valve that determines whether one or both sides of the exhaust are used. I think it helps speed up the warm up of the cat, emissions and noise. In sport mode it’s always open, but in eco or comfort I think it spends most of its time closed.
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New Tue 6 Nov 18 21:33 
 BMW 3-Series E90 - BMW 440i 2017 - Exhaust tips - Lygonos
Similar to Golf R and Audi S3, where there are 2 pipes on each side and invariably only one of each pair is dirty: a valve on the system only uses the extra pipe on WOT or 'sport mode'
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New Tue 6 Nov 18 21:40 
 BMW 3-Series E90 - BMW 440i 2017 - Exhaust tips - legacylad
I don’t know what WOT is, but when I check my 4 pipes tomorrow if any are sooty I’ll hang my head in shame. ‘Sport’ mode is my normal mode, as recommended by the dealer.
If I wanted ‘comfort’ I’d have bought a Stuttgart taxi and wafted through leben...
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New Tue 6 Nov 18 21:44 
 BMW 3-Series E90 - BMW 440i 2017 - Exhaust tips - Lygonos
Wide open throttle
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New Tue 6 Nov 18 21:50 
 BMW 3-Series E90 - BMW 440i 2017 - Exhaust tips - legacylad
Thankyou.
I daren’t do that very often.
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New Tue 6 Nov 18 21:58 
 BMW 3-Series E90 - BMW 440i 2017 - Exhaust tips - Zero
I tried a bit of WOT the other day after a spot of rain, I even got a bit of wiggle out of the rear and a slight split mu tug at the front, before lights came on to tell me it was adjusting stuff to keep me alive.
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New Tue 6 Nov 18 22:11 
 BMW 3-Series E90 - BMW 440i 2017 - Exhaust tips - R.P.
Had a wriggle from the rear of the MX5 tonight - maybe a little too much throttle and a diesely road..
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New Tue 6 Nov 18 21:55 
 BMW 3-Series E90 - BMW 440i 2017 - Exhaust tips - Zero
I have the same engine as the 440i in my 540i. The second pipe is only used when its in sports+ mode and in fast idle engine start mode.

After 16k miles one pipe is clearly dirty, the other slightly so
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New Tue 6 Nov 18 22:11 
 BMW 3-Series E90 - BMW 440i 2017 - Exhaust tips - legacylad
If you get a ‘slight split mu tug at the front’ can it be sorted by Lygonos?
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New Tue 6 Nov 18 22:14 
 BMW 3-Series E90 - BMW 440i 2017 - Exhaust tips - Lygonos
I think that's the same as tearing your banjo string.
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