Hello Danielsatur,
Thanks for your post.
I bought a 2000 ls at an auction over a year ago and have been chasing this rattle/rough idle problem for over a yr
.
No sign of COP failure but replaced a few of the coils anyway chasing my misfire codes 030x.
When I inspected the valve cov gaskets, my cam tensioner looked worn out. I replaced the cam tensioner but the new one was made from plastic. I replaced - but the rattle remained. After a ~100 miles the timing chain broke and my valves kissed the pistons. When i took valve covers off, the new cam tensioner was not torqued down all the way. My mistake, either I didn't torque it down or threadlok was required. Thinking this was the cause of the timing chain failure.
I got another used engine from a junkyard and swapped the old engine out. Still a rattle. I thought it was the bad misfire that was causing a "rattle" sound to resonate to the bottom of the engine. Since it wasn't the coils I surmised it was a bad fuel supply causing a lean condition, plugged injectors, vacuum leak, or the ECM. I Replaced the fuel pump, sent the injectors out to be reconditioned and found no leaks but my rattle remains
.
Re-reading these post and saw yours - the rattle and rough idle symptoms make me suspect that my cam tensioners in the swapped engine are questionable (84k on engine).
My question to you is - what part # did you order for your ls from that jaguar place that only cost $90. I have a 2000LS 3.9L v8.
Any help would be appreciated.