So far on my personal LR's I've replaced 3 coil packs out of 18 D2's I've owned. Not a bad track record if you ask me. I've gone thru way more spark plug wire sets vs coils.

UPDATE

I got misfire on 3 and 4 yesterday, I am not feeling anything out of the ordinary on start up or driving.

Perplexed as to why but, it was 3 that was misfiring before the coil and wire replacement.

I pulled the number 3 plug and it didn't look bad, however, the threads were very tacky.

I am going to do the Seafoam intake cleaner and see if that helps out. Already did the Seafoam in the gas tank about 6 months ago.

I replaced the old plugs in April of 2017 am using the following spark plugs:

Bosch 4 Piece OEM Spark Plug Set # 0242229620 / 4418 / FGR8DQP

Not a fan of any Bosch plugs with these engines, but as long as your electrodes aren't flush (like some Bosch plugs) and the temp range is within spec you should be okay. I prefer NGK Double Platinum/Iridium or Autolite Double Platinum/Iridium personally as they've let me down anytime I've ever used them.

I'd never heard of Garry's relocation kit. Just arched his video. What does it cost?

After the Seafoam, let's see how things go and I might switch back to NGK if that does not work. Odd that I had zero issues with them until the last couple of months.

here is the link

https://www.ebay.com/itm/LAND-ROVER-...d=113147967794

Honestly though that's how a set of Bosch plugs act on a LR. They're great at first and then they go south pretty quick vs other plugs.

I've only used them once on a LR personally (before I knew better). I installed a set of Bosch Platinum Plugs into my 97 RR 4.6L HSE Vitesse. For the first maybe 3K I didn't have any issues, then I started feeling it stumble, and then finally it triggered some misfire faults. I was like oh great my $$$ coils have gone south (because I knew it couldn't be the spark plugs with just 3K on them or the new spark plug wires I had installed at the same time). Well one of my LR buddies asked what brand plugs I used, I told him Bosch, and he immediately said that's my issue. I didn't believe him honestly, but once home I pulled them and sure enough they were fouled..... I went down and bought some NGK Platinum Plugs and I never touched the Spark Plugs ever again on that RR and I never had another misfire fault.

My 02 Kalahari ran pretty decent when I got it, and I honestly wasn't experiencing any misfire faults or issues with the wires. Then one day out of the blue I got 3 misfire faults (P0300, P0303, and P0307), found a bad wire on #3 so I figured I'd just replace the #3 wire. Misfire for that cylinder was still there along with #7. Ordered new wires, coils, and NGK Iridium Plugs, upon removing the plugs I found a set of Bosch X2 Platinum Plugs in my Kalahari. I then flipped thru the previous owners maintenance records and he'd replaced them just 13k earlier. I changed everything out and it's been misfire free since.

I do a lot of tune up's on LR's and I find Bosch plugs all the time in them. I either use the Autolite Iridium Plugs (very easy to find locally), or the NGK Iridium's if they're in stock. I always get told after a tune up how awesome their LR's are running.

Just keep em in there for now, but if nothing changes after a fuel treatment, or another tank of fuel I'd start looking into the plugs.

I will probably order some NGKs from Amazon after the Seafoam (to be honest I am very excited to try the Seafoam via the intake and see all the smoke), if I get bored I will swap the plugs to different cylinders just for the sake of argument.

Just catching up on this post...but in my opinion...if the upper intake comes off...then the injectors should come out, be tested/rebuild/replaced and o-rings replaced. I mean real, these o-rings on the injectors are now nearly 19 years old.

Me, while everything is fresh in your mind...l'd pull the upper intake again, fix the broken bolt, have the injectors tested/cleaned/rebuild/replace o-rings and check the wiring harness over with a fine tooth comb...those wires come out of the top of the injector and immediately bend over (causing stress and breakage of wires).

Plus, once you replace the o-rings...your chances of having a vacuum leak "there" is removed/reduced from future "vacuum leak" issues.

Also, in regards to ORF's comments...l'd talked about relocating my coil packs to the SAI brackets that hold the check valve(s) mounted along the tapped cover and holds SAI manifold tubes (once l'd deleting system)...but never did. I've removed all of the tubes concerning the SAI, along exhaust manifolds and firewall, so getting at the coil packs is somewhat difficult...but nothing worth changing now.

Anyhow, good luck with your future progress.

Brian.