I ended up with a LR4 5.0 that had the timing chains and HPFP's replaced before ending up with me and it hasn't run properly since.

when i got it it had misfire codes and cam/crank correlation. i assumed the chains were not replaced properly.
i pulled it apart and the drivers side bank had collapsed tensioner and the exhaust cam was off one tooth. i replaced the tensioner and re timed the motor, no more cam/crank codes.

when i got it running cleared codes, got misfire on all cyl, also had cyl 4 injector code pending. checked the injector with volt meter, it was reading open so i replaced it.

now its running a lot smoother but i still get misfire codes on every cyl, random misfire, misfire within 1000 codes, and misfire with fuel low.

pretty sure the fuel is old (maybe 1 year old) could the solution be as simple as draining the tank and adding fresh fuel?

anything else i should be looking at?

 

Kinda doubt 1 year old fuel would cause this, but I guess its possible. With a history of timing chain problems, I’d run a compression test first if you haven’t already.

With a low fuel pressure warning and that timing chain still off by a tooth with a collapsed tensioner, could be that the timing chain and HP fuel pumps were not in fact replaced, or someone messed up the timing on the fuel pumps when they were replacing the timing chains (not quite sure how, but maybe they thought they needed to get that third chain off then figured out they couldn’t). Could also be the fuel rail pressure sensor, or the low pressure fuel pump in the tank - a lot of those seem to get replaced. VVT solenoids can go bad also, but I think a lot less common than the other things.

 

Guides and chains are new, the collapsed tensioner was also new, it wasn't installed properly I think and on reinstall wasnt reset, bottomed out 100%.
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compression is 195-210 on all the cyl
i found that the misfire codes are pretty useless on this engine as the codes come up on all cyl, the live data individual misfire counters are what you need to look at.

i found that when monitoring the misfire counter only cyl 1 and 6 were incrementing as the engine runs.

found a cracked plug in cyl 1
found a new injector with additional ring at the base in cyl6, this ring caused the injector to not seat properly and i assume it caused the injector to be compressed, causing the injector to fail.

installed new plugs, cyl 1 no longer increments the counter,
moved the cyl 6 injector to 8, cyl 8 now is misfiring.
ordered another injector.

 

Nice - sounds like you’re tracking it all down. Also sounds like someone did some shoddy work on this in the past. Hope you get it sorted out.

 

installed the other new injector on the weekend and its running good with no misfires.