In my Audi S5, I would press on the accelerator the same time I would turn the key in my ignition (not during a cold start obviously; resulting into a serious exhaust note)

Trying this in the XJ8, the car cuts off? Is this normal? Can I bypass this?

 

Question is why you press the gas poedal during starting ? It is like never needed on working car. You can not bypass fuel cut mode what comes on when doing that.

 

Why would you abuse anything like that: just to hear noise? Seriously?

 

it sounds beautiful albeit probably not good for the car

 

IDK about the X308 in particular, but many fuel injection systems enter 'flood clear mode' while cranking at WOT, meaning the injectors are disabled.

 

You don't want the engine to go to high rpm the instant it has fired-up. Give it a chance, at idle rpm, to circulate some oil and build-up oil pressure.

 

car cuts injectors with foot to the floor

start the car cold, wait 5 seconds and shut it off then try to start it back up. you’ll get familiar with this feature 👍