I’ve had my 93 ls400 for about a year and I’m just now getting around to really fixing the thing. I got her for 700$ and she runs and drives, has 161k on the dash but she’s got some issues. My main issue is this ticking sound that it’s always had and overall rough running, vibrations, sometimes slow/weak start. I have no codes. It’s probably also good to mention a have some weird electrical issues just like the auto tilt going up and down when I got it off, the automatic locks going crazy when I’m near and it my seat memory not working. I also have sometimes when I turn the key to on position something rapidly clicks in the engine for like 2 seconds. I got the battery when I got the car. I got new spark plugs, ps pump, thermostat, and radiator.

Now The injectors are ticking super loud both the left and right sides. I’ve heard that’s normal but these seem super loud to me. I’m gonna do a fp test tmr to see if I actually have a problem with fuel cause I could be tripping.
Anyway, on the driver side there seems to be a different tick separate from the injectors. It follows the revs. You can slightly hear it from above by the valve cover. but When you kneel down by the driver side wheel you can really hear it from under the car, coming from the engine. To me it sounded like an exhaust leak. So I threw some gaskets at the manifolds and the cats. I also threw in some new mounts. I saw no cracks or anything in the manifolds or the gaskets I took off. There wasn’t a crazy amount of carbon build up. When I slap it all back on and crank it up I still had all the vibrations, rough running, and the odd tick.

So today I got my screw driver out and started using it as a stethoscope, all the injectors were firing, super loud ofc, and I’m checking all over the valve cover to see if I can hear anything. The only thing I heard was my cams Turing and the very back exhaust valve ticking. I’m thinking it could need adjustment. But I’m not confident that’s what’s causing my weird tick

Im hoping someone could point me in the right direction cause I’m kinda lost right now

 

It’s probably not the single source of all your issues but I would make sure to put on your laundry list to have someone pop your ECU and check for leaking capacitors. It seems like an extremely prevalent issue that can have all kinds of weird effects for us 1st or 2nd gen owners. I recently acquired a 95 and sure enough, ECU had leaking capacitors.

 

The valve tick is very common and they do, from time to time, need to be adjusted but I'm not sure of the exact schedule. My last 2 LS400s (93-94) had the tick (#7) loud enough to be noticeable but I never adjusted them. My current LS400 (93) I don't hear anything. If ya end up changing the valve cover gaskets that would be the time to adjust the valves.

Some of your other issues sounds like the ECU symptoms, with the caps going bad.
There's also the wire harness in the trunk on the left hinge which sometimes breaks and weird electrical demons pop up. https://www.clublexus.com/forums/ls-...-in-trunk.html

 

That annoying tick on the left is a classic. For some reason, the upper left cam area does not ventilate so well and may run hotter than elsewhere. The upshot is that sludge develops under the followers and the valve stem starts to drill a divot in the follower. What makes it diabolical is that you can do a valve adjustment to get rid of the ticking, and that noise is still there. It can rotate in operation and give you a nice .010" intake clearance, then when it falls into the divot, the next valve clearance check on that valve will be .025".

I had this issue on my 1992 LS, removed the camshafts, followers, and discs, and found #7 intake rear had that problem. After repairing it, engine was fine forevermore with the following warning, Change Your Oil Every 5,000 Miles Without Fail.
Colin