Just got an 96' xjr a few weeks ago.
Was driving it last week - and the motor just stopped working, while I was standing at the traffic lights!

After starting it - managed to drive it home by always keeping it in Neutral or giving it some gas, and not allowing it to stay in Drive while I was stationary.

Thought it was the battery, as I left the lights on the previous night. Checked the battery - it was Dead! Replaced the batter - everything works. Thought this solved the problem.

Driving along today. The car shuts off. Back to square one.

Any any help is appreciated!

Would be great to know what this might be so as to be informed before I go to the shop.

 

I am thinking that his could be an inertia switch. But it makes no sense - as I can start the car after it shuts down.

 

Invest in a code reader, for $100 bucks from Autozone or Advanced auto it pays for itself in one use. Even if you are not mechanically inclined you can plug one of these in and follow the directions and if there is a code you can decipher and at least know what is could be before even taking it in to a mechanic.

Sometimes that fix could be really simple, sometimes not, but these little code readers are nice to provide some direction.

 

Thanks for the advice!

Just ordered the Equus 3030 Innova reader from amazon. However, something tells me it's not going to reveal anything - as I don't see any "error" lights on my dashboard.

 

Look into the Crankshaft Position Sensor. Mine failed - car shut down, failed to start when cranking. Worked again once cold. No error codes.
They are very expensive from Jaguar, but can be purchased for less from Rockauto. Also Autozone carries the CPS as well.

 

Just a follow up - the fault was, it seems, a bad "bypass valve vacuum actuator" or "wastegate".

I am still in the process of looking for one.

 

A failed bypass valve actuator will not cause your engine to stall. A deteriorating crank position sensor is a far more likely candidate. On X300os of this age it probably accounts for more stalling and fail to start issues than all other causes put together.