'Hissing' when cold..

B

bakes100

Member
 Essex
Hi guys

Purchased my Z4M a few days ago, already solved the slight stutter at idle :thumbsup: .

Another slight issue I have is that when I initially fire up the car in the morning or just when its cold it sounds very 'hissy' but if I hold down the throttle very slightly the hissing goes away.

Is this a normal thing? As I know stainless exhausts can emit a different sounds. It becomes slightly less noticable as the car warms up. It comes from the front end of the car and definitely isn't the exhaust joint leaking.

Thanks

Stuart
 
Stu,

To locate it a bit better, get a 2ft length of hose, put one end in your ear and the other move around the area of the hiss, you can locate a noise very well this way. I've diagnosed vacuum leaks this way :)
 
On cold start a device in the engine bay pumps air into the exhaust to help the cats warm up faster. Could be that (it's the cylindrical thing near the strut by the washer bottle)
 
Me again..

I cant seem to find a leak, the more I hear it the more it sounds like the exhaust around the manifold area (low down on the left hand side if looked at from the front)

Are Z4Ms noticeably noisy from the exhaust at first start-up? Is it just me being picky or is it unusual?

It could be a leak somewhere as when its warm it quietens down, which could be as the exhaust heats up it expands.

Im going to check the lambdas are tight and go from there.

Thanks in advance
 
I have to say i've learnt to ignore the various strange noises my M produces in various different temperatures, atmospheric conditions, prevailing winds, days ending with a "y", etc

Just wait until your diff starts talking to you (but only when you turn left on the second thursday of the month)
 
hissing, ? thats nothing, i started mine up the other day , backed it out of the garage and left it running, as i walked away from it i heard this hollow loud , really thumpy noise, i was thinking ," what the f*ck is that !! "...... then i raelised i had turned on my big old compressor to check the tyres !!Doh :rofl:
 
normalish, maybe, mine seems to have quite a compilation of sounds on start up too, just the nature of the beast i think, :driving: drive on and enjoy :thumbsup:
 
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