My 1982 xjs HE V12 is starting to have some startup problems(only when starting up with cold engine).
It fires up, but seem to be idling very low, or that not all the cylinder is working. When I rev it a little the engine seems to wake up (a couple of times the car misfires at this point). But then it idles fine and runs as great as ever.
I've been ignoring this problem for about a year now, because it only does this on cold mornings or after leaving the car alone for some days. But the last couple of time, when I rev it a little to wake up the engine, as I put the foot down on the gas paddle, the idle will fall as if it would stall, but only for a very very short time, and revs back up normally again. And again after a few seconds after that the engine idles and runs fine again.
However the car never shows any sign of problems when the engine is warm or while the car is driving.
Many thanks,
Niels Olesen