2000 ls400, stock except for a deletion of the back two mufflers, front two still in place. 171k miles

my cats are bad but recently, after replacing my old battery with a neverstart, I’m now getting a p1346. then
the engine idles rough. I have a scanner and immediately after clearing the code it idles fine.

tbelt isn’t due but I don’t know if the previous owner changed the plugs. before the neverstart I had the cat code but it never gave the vvt code. it also displays “check vsc” which also goes off after clearing the codes.

I saw a thread saying this was usually caused by a bad battery but my old battery needed to be jumped everytime I started which is why I replaced it but it never gave the p1346.

obviously I need to address the cat code but the vvt and rough idle are more concerning so I want to focus my finances there. I haven’t had the battery checked, I plan to clean the maf with throttle body cleaner and replace the spark plugs (she still pulls well so not convinced that’s an issue)

any other thoughts?

 

i would start with the VVTi oil control valves. start with a clean, then if still persistent it might need complete replacement.
https://www.clublexus.com/forums/ls-...-ls-400-a.html
https://www.clublexus.com/forums/ls-...349-p1346.html

the check VSC is just a companion to the CEL. it goes away once the codes are removed (assuming the issues with the codes are fully resolved as to not return the CEL again).

 

I'd start by using an engine flush and de-sludging the engine. The cam solendoids usually just get gummed up. But they can be removed and cleaned too. You will also need to scrub out the throttle because each time your battery dies or is disconnected or replaced, the computer loses saved throttle position memory. You'll have terrible idle quality until it's cleaned out like new.