Fuse 15

[mickjaguar]

Best analysis for the Ppf cars was a write up on the US forum. (I probably put a link on here somewhere in the past). The valves are sneaky, they can be open when you startup, but as soon as you apply revs/move off they start to close. Pulling the fuse easily confirms this. (P300 might throw limp home mode, so different for those cars somehow).

[jagseven]

Gosh - I was beginning to think I was becoming an expert on the exhaust variations but it seems not!

[scm]

The valves are sneaky, they can be open when you startup, but as soon as you apply revs/move off they start to close.

On my MY18, the valves close as soon as I select D, so a (relatively) quiet start is possible if I'm quick after firing it up. I can't stop it waking up with a big snarl, though!

[Lady Eleanore]

The car is nowhere near as loud on startup, as my old M4 (F82) with the BMW MPE (titanium) exhaust, with or without the valves open.

[jagseven]

My car certainly starts with valves open (so loud) and seems to behave as mick says…very sneaky
I suppose if car starts with valves open (like mine) that would explain why pressing exhaust button makes no difference - it’s already in loud mode!
Then it goes into quiet mode as car is put into Drive

[davidls]

so mine would start in quiet mode if I don’t put it to dynamic or press the exhaust button. I will have to get someone to then put it into drive whilst watching the valves and see what they do, it would make sense if they then did start to close as it’s quieter at low revs u til you get the revs up when it starts to growl again.

[Lady Eleanore]

I think the car (at least mine) starts with valves open and slightly higher revs, to warm up the cats and such like, for emission purposes. But it does so on a light throttle, so it doesn't sound anything like when you have proper load on the engine, even at lower revs. The fuse 15 trick means that start up sound pretty much the same, valves open and a light throttle, but as soon as you put load on the engine, even at low revs, you get the 'happy' noises. Grrrrrrrrrr, woofle woofle woofle

[davidls]

Under normal circumstances, mine starts with the valves closed however does run at higher revs for about 60 secs before it throttles back. If I push the valve button it opens them and the sound is considerably louder.

[Deleted User 4828]

I always let my v8 run high on start up, I never pull right away on cold start up. I wait for the revs to back off to normal tick over then engage D, or reverse. This time I beleive is to allow the cats to get hot and also ensures oil is reaching the top end of the engine. I have noticed on my car, that after driving for a while at and normal temperature has been reached, stopping for 5 - 10 minutes getting back in again, it starts to run through this higher rev time again?? Nothing to worry about I'm sure, just some quirk with the s/w. I don't bother to wait at this time I just continue as the engine is still pretty hot, I suppose the cats would cool quicker.

Anyone else experience this?

I remember in my VXR's, the stop/start....mode when activated and engine stopped, with car in neutral and handbrake on, opening the door to get out it would sense the voltage drop on the battery as the lights came on and start the engine when you were climbing out! A bit disconcerting, but perhaps over sensitive on the monitoring of the battery. I didn't make a habit of getting out of the car in start/stop mode it's just something I noticed.

[Thunder Dump]

In *any* mode, pressing the active exhaust button will open the valves at *idle only*. As soon as the RPMs start to move the valves close and then don't open again until higher RPMs, depending on mode and exhaust button. When the fuse is pulled, the exhaust is wide open all the time, including from idle to about 3500 RPM (lower in Dynamic mode). What you get from pulling fuse 15 is having the valves open from idle up through 3500, which makes a difference in regular driving where you're not constantly going higher into the rev range.