I have a 2001 Xterra se with the 3.3 v6. And there is what sounds like a lifter tick or valve. Are the valves on the 3.3 adjustable or hydraulic? Also this caused the see light to come on and comes up as knock sensor. Any ideas?
It has hydraulic lifters..
but the noise can be deceiving as the injectors can make quite a racket on their own.. does it tick at an idle? does the tick go away with some revs?
Knock sensor failure is a pretty common issue (not related to your ticking) and theres a lot of info already on this site about it.
The sensor just senses knock. If its knocking, changing the sensor fixes nothing.
If its a tick, also try to see if it goes faster/slower with RPM, AND, stuff a rag in the exhaust (Unless you have asbestos hands, etc...) to block the exhaust, and, see if the ticking gets LOUDER when you block the exhaust.
You might need a buddy to do the gas pedal while you stuff the exhaust, or visa versa.
If you don't have a buddy, the ticking is then a minor problem, and you should concentrate on making friends first.
The exhaust manifolds on these trucks do crack like crazy, and can sound very much like a lifter tick. In addition on the driver's side of the engine bay there is an evaporative control solenoid for the emissions system that sometimes runs on a duty cycle and makes quite a bit of racket, but it doesn't follow engine RPM. If you put you hand on the solenoid that has the two hoses going to it... one with a green cap... you an feel it and see if it lines up with what you're hearing.