P0300,p0305,p0308
 

Need some help. SES on. pulled codes and this is what I got. Engine stumbles. 2000 Discovery with 103k. I was told that cyl. 5 & 8 share coil pack signal and that with these codes that coil pack is bad. What do you think? Just got Disco a few months back. Looks like plugs and wires are oem. Changed 5 & 8 plug on the fly. Made no difference in performance. Obviously will change all plugs but have a little indecision. Do I change wires and see if that repairs problem? Or after the fight to replace wires, do I need to go ahead and replace coil pack while I am there. The best that I can see is that I must buy complete coil pack for all cylinders or is it available by cylinder or pairs of cylinders? Thanks for help

There are two coil packs and you can buy them as a pack or you can buy them one at a time. And its common for them to go bad. you can replace it without pulling the upper intake if you want, if you have secondary air you can pull out the air hose by pulling off the heater hoses and slipping out thru there. Not easy but it does work. the four bolts that hold the bracket in are further down on the lower intake, just use a flashlight and 8 mm swivel socket to reach them. the bolts that hold the coil pack on is seven mm.

I had about the same codes on a "new" '03 with 100K, along with misfire codes all over. I tried new plugs only, didn't work. Then I did new coil packs and magnecore wires, fixed problem, cleared codes, purrs like a kitten.
I took upper intake off b/c I was doing other stuff as well and I was not familiar enough with the work, you go a bit blind the first time. Good luck