Valve cover & PCV vents - Important Info!

Wanna share some into for anyone that may be wondering about the importance of these seemingly unimportant parts and how they NEED to be routed. I did a motor swap last year after my OG motor grenaded 2 spark plugs and sent metal all throughout the cylinders. (spark plugs were loose and with the extra boost from the SC it blew them out and up) so periodically check your spark plugs!

Back to the subject - Put in a JDM 3.4 that looked clean and have low miles allegedly. Motor fires up, sounds fine, seems to run fine. First time out in the desert I notice it just doesn't seem to have the extra "umph" that the old motor did. Whatever, nothing I can do. As I drive it more, I realize its getting worse. Pull a spark plug, it looks lean. I pull the 7th injector to test it to make sure it's firing...it is. I have a digital scan gauge, its actually showing the timing retarding (down to 7 degrees at WOT) as I mash the gas in higher gears, truck is falling on it's face. it's also running hotter than it should...thanksgiving in glamis, 65 degrees out and its so hot you cant even touch the cage tubing around the motor. So something is really wrong.

Back home I figure it out. Believe it or not, it was the valve cover vent hose being routed wrong and PCV being bad. I had left the PCV that came with the new motor in, and it was clogged up or malfunctioning or whatever. I put my PCV in from my old motor. Then the rear valve cover vent hose on the driver side I had just running out behind the motor with a filter on it. I re-plumbed that back into the air intake like it was from the factory. Went out and drove the truck and boom - problem solved. Timing did not drop below 15 at WOT in 4th gear, and the power was back. And the truck ran cooler, back to the temps it should.

So here is what was happening. The 3.4 is a closed loop crankcase venting engine, if I'm saying that right...with the valve cover vent hose vented to the outside air, it was sucking instead of venting (pushing air out) this was causing pressure to build up and not be able to go anywhere, so it pushed out every little possible area where it could, blowing oil out the manifold to supercharger gasket mounting area, and the throttle body (I noticed this once I really started looking at it) The pressure increase in the motor threw off all the sensors and made the computer think the truck was wayyyy over boosted I assume and that caused the computer and the knock sensors to kick in and retard the timing. I had it all figured out step by step back in December, but that's basically the gist of it. So once I vented everything correctly (intake sucking air FROM the valve cover vent, thus relieving the pressure and putting in a properly working PCV valve) everything went back to normal.

So there you go. Don't mess with factory stuff lol. Its there for a reason.