I bought a 2000 ls300 with a 3.0. It had a blown engine. I bought a used motor and installed new plugs, valve cover gaskets, water pump, all timing components, and put the engine in the car. Engine runs, but throws a p0301 cylinder #1 misfire. It also backfires in the intake. I've checked the timing multiple times and its spot on. Not for sure where what else to check. If it was just the p301 I would check plug, coil, and injector. But with it backfiring, I'm at a loss.

 

Welcome. Please check compression and report back.

 

No compression on cylinder #1. This is the 5th engine I've gotten that has had compression issues. 2 from on place, 2 from another, and this one from a different one. Going to call tomorrow and see if they will help pay to have the heads reworked. Its under a 90 day warranty. ugh and double ugh.

 

These are interference engines, so when the timing belt breaks the valves bend. Sorry for your troubles. These are nice cars when they run correctly.