I was going by what swajames said:

If it isn't actually temperature related but running the car briefly makes a difference, then it's a question of determining what is different one start to the next.

Since the only real volume control the car has is the exhaust baffles it stands to reason that those are the thing that would make the difference from 1 start to the next. Doesn't make it true, but it's a hypothesis at least.

One way to test this would be to disconnect the vacuum line to the actuator or pull the fuse on the pump. If it is then turned up to 11 every time, then at least you know the real cause for the difference and those so inclined could potentially do something about it.

 

ccfulton, I think Foosh is right, it's ecu programming. The behavior we see is what Jaguar wanted. It's what we all want most of the time, just not when we have those occasions when we need to fire her up at 5 am or midnight. I don't think you're going to get any different behavior unless you can change the software. Jaguar probably ought to add a stealth mode at some point, it doesnt strike me as a difficult feature to add, but until they do I'm not sure we're going to have much success fiddling around with the hardware side of things.

 

Not forgetting that the reason it is preprogrammed in, is to bring the cats and lambda probes et al up to temperature quicker. Once you're hot, the mixture, timing and everything else can be settled and you're done.

Potatoes, I tel ya...they are the way forward ;-)

 

There is another method of volume control called the throttle. What I was trying to convey to you is that base cars in 14-15 do not have the valves std, and my car is one of those with no valves. It also cold starts by revving up to what I would estimate to be about 3K RPM. Since the electronic tach gauge needle cycles from zero to max and back to zero on start-up I don't what the exact RPM is. The ECU is programmed that way, and it has nothing to do with the valves on the active exhaust system. On a warm start as SWAJAMES said, it does not rev nearly that high.

 

Why doesn't someone just plug in an OBII reader and watch to see how high the revs go when they start?

 

My ear tells me all I need to know, and I know what the engine sounds like at various RPMs.