Postby smj999smj » Sun Feb 15, 2015 6:37 pm
If you have no catalytic converter, it will trigger P0420 & P0430 trouble codes unless you use some kind of rear O2 sensor simulator. The ECM wants to see a 2:1 cycling ratio from front to rear to tell it that the converter is working efficiently. Also, if you gut the converters, make sure you get every bit of the catalyst substrate out. The Pathfinder uses the variable timing to accomplish EGR rather than a conventional EGR valve. It cracks open the exhaust valve during the intake stroke, pulling exhaust gas back from the exhaust system into the combustion chamber. If there is any bits of honeycomb loose in the system, it can be sucked back into the cylinders, scoring the cylinder walls, much like what happened with the early L31 Altimas with the QR25DE engine when the front converter started to break down.