Either unplug the injectors (below the inlet manifold) there is a plug on each one, feel your way in from either side to get at two from one side and two from the other. Feel the tab on each and gently lift up whilst withdrawing the plug. Be gentle getting your hand/arm in not to dislodge anything else.
I have attached a video of someone taking bits off a very similar engine type so you can see where you are going, along with the below pic of the injector plugs. You will need to remove the air filter box and air pipes to give access, be careful removing sensors, see how the guy in the vid goes about it so you know the method. You don’t need to be taking the inlet manifold off.
Or F10 (30a) in the fuse box under the bonnet, but it shuts other things off too.
With fuel stopped, remove your coil packs (creature of habit I mark each one as to which cylinder it came out of…yours are all new so maybe not).
Remove your plugs (again mark location……..though again yours are new).
Insert pressure gauge into no 1 (take absolute care not to drop anything into the spark plug holes, placing a rag over the exposed holes can seem like a good idea but can get sucked down)
Crank for aprox 5 seconds to allow a few full rotations to ensure max pressure is achieved on the gauge, note reading.
Repeat across the rest of the cylinders.
It may be worthwhile depressurise the gauge and repeating on each cylinder so you have a couple of reading on each.
The noted pressure should be about 245psi (17bar) for normal, with 200psi (14bar) at the low side. Maximum deviation across the cylinders should be 45psi (3bar) (manual states 75psi (5bar). Depending on your gauge you may need to convert the unit of measure (bar, psi, kpa) Numbers shown are rounded slightly.
If your readings are low you might want to try dripping about 5 mil of engine oil into each plug hole one a a time and retest each cylinder. This will give a bit of additional sealing of the rings to bore during the stroke and can help identify worn rings/bore. if you do drip oil in try not to get it on the spark plug threads as this can affect the torquing of the plugs.
Also, tho you haven’t probably got any mileage on your new plugs to show anything, take note of their condition, ie wet black etc or a photo, may be of use later.
I am not going to say anything else at this point as you seem to be getting flustered and seeking worst case scenario’s, maybe my fault for too much information at a time, wife says I always go into too much detail all the time. A compression test will give you a reasonable indication of engine condition. Then you can start to rule things out. Just note that if you do drip oil into each cylinder that when you do next start it there may be a few puffs of smoke from the exhaust as the oil burns off.
Also, while you have the air pipes out of the way on the gearbox side, measure you hpfp diaphragm while you have access to it.
