2003 Disco, so I had a misfire on cylinder 7 the other day. Upon opening hood I could hear and see it arcing off the fire wall. I decided to change all plug wires ( spark plugs where changed a month ago so no need) the coil pack is fairly new as well. After disassembly and reassembly go to turn the key starts up strong the immediately dies tried cranking it at least a 100 times still same results. Checked all fuses battery is brand new and is fully charged double checked all my work as well to find nothing. I'm at a loss I've tried resetting the inertia switch resetting the security system I even took it back apart again to double check the fire order and everything checks out. Also during a couple of those 100 cranks I heard a backfire around the manifold area. Please help

 

The only other posibility is CPS. Always good to have a spare. Where are you?

 

So after assembling and disassembly at least 4 times to double check my work, I decided to check the vacuum lines, to me it sounded like how it would sound if you tried to start with MAF unplugged so of course I did the cigar test and smoke is coming from around the front and back of where the intake manifold meets the cylinder holes I'm going with bad gasket and poor alignment of intake. I played with it earlier and tightened it back down still failed smoke test but runs a little bit longer before dying. So bad gasket? Also I can't get her to throw me any codes after at least 150 starts now so sorry.

 

Update so ordered a new gasket took out old turned out to have a flat spot on one of the cylinder hole areas where it's supposed to be raised a bit. Now truck is puring like a dying cat.