Any ideas on this non starting problem

[flying]

The car has been running not the best of late so have put another coil pack and was much improved also today checked spark plugs and leads, replaced leads and took the car for a short run nearly back to normal drove the car back to the garage to put the plug cover back on restarted the car it ran perfect for 4/5 seconds died and will not restart any suggestions most grateful.

[al 350i]

first thing to do is find out whats missing?

check that you've got a spark, check that the fuel is coming through and check that air isn't being restricted. if all these are present then you'll have to do a compression test, although this would be pretty serious and i would guess that its something simple.

probably just an imobiliser problem, fuse/relay or crank sensor

[flying]

al 350i
Thanks for the suggestions made us rethink on what we could be missing having checked everything that we could think of,turned out that there was a blown fuse to the coil pack which we hadn't even realised was fused.
Cheers

Mark