Engine start noise - The Unofficial BMW M5 Messageboard (m5board.com)

Haleakala · 17th July 2001, 13:38

It doesn´t sound good for about 2 sec when starting the engine.
(sounds like a smattering noice)
It appears only sometimes and only when the engine has been turned off at least a couple of hours.
Is this a known problem?

whirlycopter · 17th July 2001, 14:00

Is this once the engine has actually started or while it is cranking on the starter motor

Haleakala · 17th July 2001, 14:10

I´ts just when the engine has been started.

johann · 17th July 2001, 14:19

Quote:

Originally posted by Haleakala
I´ts just when the engine has been started.

Where in Sweden are you located?

Haleakala · 17th July 2001, 14:23

Stockholm.
M5 ´00 Avus blue

whirlycopter · 17th July 2001, 15:04

It could just be the cats. When the engine is on cold start, and running rich, extra air is drawn into the cat to ignite the unburnt fuel to warm the cats up and stop the matrix being contaminated. I notice this noise occasionally on my e39 but my e34 used to make a load of noise while it was doing this.

whirlycopter · 17th July 2001, 15:07

Sorry forgot to write that this sounds like a slightly leaking exhaust manifold, a sort of hollow ticking noise. If you've ever had a leaking manifold you'll know what I mean!

Russ · 17th July 2001, 15:23

Yeah... Mine does something similar:
Occasionally when I start it up (from a cold engine condition) I get a little sputter (back-fire?) during the first couple of revolutions...

It settles into a correct idle immediately after that though.

Haleakala · 17th July 2001, 15:51

Russ,
It´s like you said.
Have you always had this noice?
I´m almost sure I didn´t have it last season.
(last season=first season)

Russ · 17th July 2001, 16:05

Haleakala,

Yep. Since it was new. I specifically remember the 1st time I started the Beast up at the dealership, it actually gave a little back-fire! I said to my salesman: "Sorta like a Harley, eh?"

The engine runs just fine after that, so I continue to ignore that initial (intermittent) sputter.

I consider it to be fuel-delivery situation. At initial start-up, it takes a couple of cylinder cycles to get the proper: intake-compression-combustion-exhaust rhythm going.

I've always assumed it was a nature of the Beast!?

Anyone else seen this?

EDIT: To clarify what I meant by "back-fire", I probably should have said "cylinder mis-fire". When it happens, I definitely notice the sound and a subsequent shake in the motor. I don't know if the computer would actually catch this as a "mis", but I suppose I could have them check the log next time I'm for service?