Tcgardner

Sorry to start a new thread for code 52 but I couldn’t find anything that matched my circumstances. I have a 95 V6 3.0 3vze. A year or so ago I started getting intermittent code 52 CEL. It’d only pop up after driving on the freeway at 65mph for a few minutes and would go away after a while. A couple months later I noticed a ticking from a bad fuel pressure regulator and then a month after that my engine blew up with no definitive cause. All I know about the previous engine is that it was beyond repair (per an experienced shop owner here in Cali. Owner built dragsters) basically all I know is that piston #1 smashed the spark plug. There was lots of debris in the block. Fast forward a few months and I rebuilt a completely different engine out of a 1991 4runner (still 3vze) and I’m still getting code 52. I didn’t change the wire or sensor and yes I know that was extremely dumb and that’s likely it. However my truck is failing the sniffer test when I smog it. I’m getting really high NOx levels. But everything else is really good. Basically I’m wanting to know if there’s anything exterior engine that could be related that I should check before tearing the engine apart. forgot to mention the code comes on new engine the same as the old. Pops on at high RPM under load. I’m not knowledgeable enough to know if my HC’s are low because it’s running lean indicating a vacuum leak