I've never replaced a set of spark plugs, yet, but am thinking of changing mine as the engine is still apart enough that I can easily get at them. With the engine cover off and the rubber NVH covers removed, you need to move the injector wiring harness out the way, release each connector to the coils, remove the torx screw holding the coil in place then remove the coil. The plug requires a 14mm tool, preferably a standard length one with a locking extension. Here's a pic from my XKR engine. I think in the XF the engine is fitted further back to the windscreen wipers and scuttle panel need to also be removed? Not sure, there's probably a few videos on Youtube. Apparently, you need to add time for cursing and swearing. Refitting the NVH covers has their own extra time needed for cursing and swearing, spraying them with a strong soapy solution helps a lot, I've read.

 

Thx.
Unfortunately the cylinder that's reporting the miss fire is #8 at the back so I do need to remove the scuttle.

Hoping it's just the coil (though I will need to order one). As stated I have the plugs and will swap all if one plug has failed. If I knew which make of coil it is I'd order one. it's either a Bosch or Delco....maybe!

Can't believe how difficult it is to figure out when just looking......to think flumoxed by a plug change when I've done jobs supposedly far more taxing. Watched several vids but non are that clear. 🤔

Looking fwd to the cursing....not 😂

 

swap coil packs around to test the pack and see if the fault moves, more than likely the coil pack over the plug IMHO

 

Gav. Thanks. That's my plan. But I have also ordered a genuine coil in anticipation - Arrives tomorrow. Bosch £46 on Amazon.
Need the car for Friday..... Thursday evening will be fun.

 

I did also get a low pressure fuel warning on one bank but hoping this is caused in some way by the misfire.

 

I did also get a low pressure fuel warning on one bank but hoping this is caused in some way by the misfire.

Hmm, I don't understand how this could be reported, the system uses twin HP fuel pumps that both feed the joined high pressure fuel rails, they're effectively a single common rail with only a single fuel rail pressure sensor. Maybe although it is logging a DTC for low pressure in one rail, that's all it can log and not monitor both rails (it physically can't with a single FRPS)? I'd be clearing the DTC and checking to see if it returns. It could be a failing injector, they're known to leak as they age, you'd need to monitor the fuel trims to see if the ECU is trying to lean off one bank due to excess fuel to one (or more if multiple leaking injectors) is being allowed to the combustion chamber(s). Leaking injectors could cause a drop in the expected pressure in the fuel rail?

 

Will go back and check codes

 

Apologies. Just checked picture - it isn't specific.

 

Cylinder 8. Back right of block, next to bulkhead (passenger/LHS on UK car)?

 

That went well. Total time was about four hours (with some help) to swap one plug and coil (just No. 8).

Now I know how it's probably less than 2 hours work. While I do wonder at people who take 2 days (it's not a race) I did only swap one cylinders ignition.

As it was only number 8 I also didn't need to disconnect the fuel or coolant lines which probably didn't save anytime but saved spillade and top up.

We did try to avoid removing various parts but in the end had to remove;
Engine cover (not fitted)
Coolant header tank. Moved aside
Cross brace
Scuttle and wipers
Cover that goes around fuel pump
Rear engine cover (sits beneath scuttle not sure what it is called)
Pulled nvh foam aside

Tools
10mm ocket and ratchet ring spanner
13mm socket for wipers
14mm socket
Extensions and Flexi drive (needed for rear bulkhead bolt)
Pick tool for coil connector plug. (Flip laterally and pull)
T30
Spark plug tester/meter came in useful and convinced me it was the coil

Not forgetting the flexi stick magnet and meter rule with gaffa tape to recover dropped bolts!!!

Second set of hands helped pull bits aside but really we should have just taken apart from the start. Many bolts weren't that tight!!!

I have further work to do and will probably swap the rest of the plugs (not needed as the plug removed I tested and found to be good). But will ensure I have the right tool for the fuel and coolant quick release connectors as I dint want to break them

Cost: one set of plugs £86 /Bosch coil £46

 

Well done, and thanks for the write up.