Alright, so I have tried to cover all my bases, but I am used to working on old cars... like carburation and what not. All the new cam phasers and what not in this engine are new to me... not that I don't understand how it works or anything... but diagnosing and fixing issues with it has left my head hurting. Anyways, on with my issue.

So I bought this truck knowing it had issues, but it didn't have any issues with the engine. It had the typical key issue, but once I figured my way around that, the engine would start and run so well I would have made a bet I could balance a coin on it while it was running... it was beautiful.

Then, all of a sudden, I went to start the truck to move it from one garage to the other (so the whole time I had it I never had it out in the weather... so no rain, or even water or anything like that) and it started fine, ran fine for about... ehh... maybe 1 second... and then just started massively misfiring as if it was missing on half the cylinders. The engine had literally almost 0 power. It was idling really REALLY badly around 3 to 400 RPM. The service engine light started flashing because I needed any warning that my engine sounded like it was going to fall out (dumb joke is dumb)

Anyways, naturally I killed it as soon as this started happening and started troubleshooting my way through everything that I could think of (and with help from the RR gods of the interwebs). So the first thing I did was to try and pull the codes. After sifting through all the misfire codes, I came across P0347 and P0011 which are Camshaft Position Sensor A Circuit Low Bank 2 and A Camshaft Position - Timing Over-Advanced or System Performance Bank 1 respectively. Since both of them went wack, my first thought was, "Maybe it's low on oil so the cam phasers can't work". Checked the oil... oil level is fine. Pulled the cam covers (or whatever you call them) so I could get to the coils, pulled all the coils (and kept them in order) and Ohmed them all out... they were all fine. Pulled all the spark plugs, and after much deliberation to try and figure out what side of the engine I was looking at, determined that it was plugs 5 through 8 that were covered in gas. Well that had answered the fuel issue, so moving on from that I decided to test compression. Cylinders 1 through 4 had roughly 155 to 160 psi compression... pretty darn good... cylinders 5 through 8 on the other hand had virtually no compression. Lovely.

Assuming the worst but hoping for the best, I got a bore camera and stuck it down into the cylinders to see what's what... and quite frankly... what I saw left me rather... confused.

Cylinders 5 through 8 all had no scars on them from valves hitting the piston (which I never heard in the first place, but if you would have heard this thing running, you would understand why I expected the worst). I looked for scoring on the cylinder walls, and while I could see vertical lines... they didn't really look all that bad honestly. So after going through those 4 cylinders and seeing almost no damage (no valve imprints, not much scaring, no cracked cylinders... nothing... bad) I decided to go look at the other side... the side with good compression... and they looked identical. I could see little vertical lines on that side as well.... nothing that looked really bad... but enough that I could see them. Odd.

So after that confusion, I decided to try compression test it again... thinking I messed it up somehow? Slapped my compression tester back into cylinder 5 (it had been 2 days now as it took a little for my bore camera to show up... but remember... I rolled over the engine a few times so that I could reposition the pistons so I could see in all of them) and went and cycled the engine... the first 3 piston strokes actually built full compression up to about 150 to 160 like bank 1, but after those first 3 hits, there was nothing... released the compression and tried again, no compression. Same with the other 3 cylinders, still no compression.

Whaaaatttt....

Honestly at this point I am just so confused that I feel like I have no idea what I am doing with this thing.

It feels like everything is still actually working... but its not getting oil pressure to the Vanos system... or a sensor is dead and it's not reporting... I am just... so confused...

 

So... after toiling with this issue for months and getting no help... I figured I would come back now and update the thread just incase there is someone out there like me with these symptoms that just happens across my thread looking for answers as I was.

The solution ended up being that the reverse thread nut that holds the VANOS system in place on the side of the engine with cylinders 5-8 (Drivers side US, Passengers side UK) had let loose from a previous, incorrectly done timing chain job. The Cam Bolt and Nut both let go (and in my case I got INCREDIBLY lucky) so that while the Cam bolt backed out, the VANOS Nut was also backing out. When it finally hit the end of the bolt, it wedged itself on the face of the engine which saved it from falling all the way down into the oil pan, or potentially getting wedged in between something. The cam, when it came lose, I also got very lucky with and actually sat itself oriented with the valves all open... but only slightly so that they were leaking, but not open enough to hit the pistons... I got SUPER lucky there.

The solution was basically to disassemble the entire top end of the engine and rebuild everything as if I had actually done a full timing job. I tore everything down enough so that I could inspect the condition of everything, and sure enough, everything looked new. It even looks like it had the newer timing kit installed. Its just the job wasn't done properly.

Just incase, I tore down both sides of the engine, and in doing so replaced all the gaskets, replaced both VANOS solenoids (they kind of fell apart on disassembly despite using the correct tool), set the engine up on its cam timing blocks, reassembled the side of the engine that fell apart (with Loctite as that was recommended on one of the forums), retorqued everything on both sides to spec, then just went about reassembling everything on the engine.

Once I had it ALL put back together... or at least enough for me to cycle it over... I did a compression test on all 8 cylinders... all of them fell in the 155 to 160 psi range. Nice.

Reassembled the rest of the way, got in, turned the key, fired right up. It ran beautifully. Spit a lot of smoke on the first start, but I am going to attribute that to me accidently getting oil in the spark plug holes or something as it seems to fire right up every time without fail and runs great.

 

THANK YOU!!!! I also have a 2005 Range Rover HSE, which was running AMAZINGLY!!! With other issues; suspension, Fuse issue to turn the key..... Very similar to your situation. The engine ran beautifully, I bought it a year ago...
About 2 months ago everything stopped I started having misfire issues in the same cylinders and had no power when I accelerated. The Failsafe Engine Mode warning has been on. I haven't been able to start it for about a month. I believe it might be the alternator.
The DTC is the Camshaft Position Sensor- I am going to follow your instructions and see if the same problem is what caused my issue.

****I will update you when I have finished!!!!
I love my car and I am praying that this will be the fix!!!

 

I hope this does help with your issue. To help a little more, I followed this guide.

Beisan Systems - Procedures - M62TU Vanos Procedure

Now, in that guide they did a full timing chain replacement, but I didn't need to do that. I just had to retime the one side and tighten everything back up. So a lot of steps can be skipped. You don't have to pull the entire front of the engine apart, but at minimum you do have to take off the Ignition coil cover, ignition coils, spark plugs, valve cover, and then the weird little half piece on the front directly in front of the cam gears as their just isn't enough room to turn anything in there without removing it... plus everything that is in the way of course.