i have a x type 51 reg 3.0 v6 sport,
when it is cold it only runs on 5 cylinders but when its warm its ok,i have had it code read it says no 1 injector missfire,i have read the battery cable can cause it to short out, where is the no 1 cylinder look from the front of the car? is it the back left hand corner + can it be easly removed?

 

Attached is the cylinder layout for the V-6. It is the right hand cylinder nearest the firewall of the ar.

 

That is a diagram for the S type.
The X type engine does not sit in that position, it is transverse.
I believe #1 cylinder is rear bank (next to firewall) far leftside plug
1 3 5
2 4 6

 

To get to the spark plugs on that bank you'll have to remove the inlet manifold. Check for oil on the plugs as well as an indication of worn gaskets that need to be replaced (valve cover/rocker cover gaskets).

 

you are right iownme. I forgot to add change front of car to front of engine. They are the same number and firing order for s and x.

 

This post has a picture of the engine with number labels by each cylinder: https://www.jaguarforums.com/forum/x...2/#post1070510

+1 to Vern and iownme: #1 cylinder is the firewall side, "front" of the engine, near the serpentine belt & timing chain.

+1 to Revere: Remove the upper intake manifold to access and check for oil in the #1 spark plug well. If oil is present, remove the valve cover and replace the rectangular gasket around the common sparkplug well. A picture of the valve cover underside with the rectangular gasket groove is here: https://www.jaguarforums.com/forum/x...4/#post1332557

Three additional suggestions:

1) Remove the upper intake manifold only when the engine is cold. The bolts between the heads screw into brass inserts in the lower intake manifold, and these inserts can break free if the engine is hot when you loosen the upper intake bolts.

2) The valve cover gaskets are sold in pairs, so if you replace one, replace both. They are probably the same age, so if one gasket leaks oil into the spark plug well, the other gasket is also nearing end-of-life.

3) Swap the #1 and #2 coils and see if the misfire moves from cylinder #1 to #2. #2 is on the radiator side, also at the "front" of the engine by the serpentine belt & timing chain. If the misfire moves from cylinder #1 to #2, replace the #2 coil, which is the easiest coil to access.

Good luck and ask if you have any questions.