[tommy_sn]

Hi
Is there any temperaturelimit for when the "cold start" program is deactivated?

[M2siast]

What are you referring to exactly?

[tommy_sn]

When starting the car there is a "cold start" mode/program that maks some exhaust noise. Valves a little open?
It seems like when it is cold (under 0 deg C) the valves are shut so there is no extra exhaust noise. I was wondering what the limit for the different startup modes was - if there is any.

[M2siast]

What happens on a cold start with any new combustion engine car is the warm-up sequence of the catalytic converter.
The sound is higher because the car is injecting more fuel to create a torch-like effect on the catalytic converter to help it warm up more quickly, to become efficient earlier.

What I suspect you’re observing is turning the car on after having driven it recently, and the catalytic converter having been deemed as warm enough by the DME, so the warm up sequence doesn’t happen. It’ll happen in any ambient temperature but not if the cat is hot.

Confirm you observed this after driving for a while? Say, if you leave it outside overnight, and it’s below 0, you should still observe the warm up sequence (and the loud noise it produces).

[tommy_sn]

It appears when it is cold, and the car has not been driven for some days - so nothing is warm. Looks like the flaps are totaly closed when it is somewhere below zero. Them might have a slight opening when it is a little warmer when doing the cold-start cycle.

[M2siast]

Originally Posted by tommy_sn

It appears when it is cold, and the car has not been driven for some days - so nothing is warm. Looks like the flaps are totaly closed when it is somewhere below zero. Them might have a slight opening when it is a little warmer when doing the cold-start cycle.

And you’re sure you hadn’t hit a preset (M1/M2) that change the engine to Sport?

All in efficient every time?

[tommy_sn]

Efficient every time - yes. But I have to wait til it is colder to test again.

[STI2M2]

I've experienced the same when starting my car on colder days. The exhaust is notably quieter.

[Bearded-Driver]

its going to be quiet no matter what in efficient mode... M2 mode will start with both flaps open.

Get in the car when its cold. Press the M2 button once and press it a second time to confirm... THEN start the car the exhaust flap will open.

im sure theres a fuse you can pull for the exhaust flap if your that concerned with the should of a cold start.

[M2siast]

Originally Posted by Bearded-Driver

its going to be quiet no matter what in efficient mode... M2 mode will start with both flaps open.

Get in the car when its cold. Press the M2 button once and press it a second time to confirm... THEN start the car the exhaust flap will open.

im sure theres a fuse you can pull for the exhaust flap if your that concerned with the should of a cold start.

That’s not how it works man.
M2 can be quiet too. It’s just a preset. You just happen to have set your M2 to engine Sport/Sport+.

I’m surprised the engine is quiet when cold. I’m wondering if it’s a DME setting, or if the flaps get frozen shut when it’s cold (because, after all, just water passes there and when it freezes they might get stuck).

OP, if you could run some tests with video, we can learn something. I don’t think this is documented in BMW’s S58 technical documentation. Interesting you guys noted it!

[tommy_sn]

There is a bit more noise in sport - but definetly more noise when not so cold.

Sport and sport+ should be the same?

[Angmar]

I’ve actually experienced this myself on really cold days. Honestly I chalked it up to the flaps being frozen because after running for a couple min and the exhaust heating up I heard them click open. Has happened at least a few times so far this winter. (Daily driver)

[Baller]

I bet its colder where I am and it never does that or never did.

[KC87ZB]

Maybe mine operates differently. Whether hot or cold I can preselect Sport or Sport+ and the car will start with flaps open.

When cold the car runs the idle up whether flaps open or closed. This makes the car seem louder on a cold start than a hot start.

I would ask if you have ASD disabled because if you don't you could be hearing artificial sounds in the passenger compartment.