My buddy Michael and I *FINALLY* had some time to throw the Pathfinder up on the lift and play with our new O2 exhaust pressure gauge.
Driver's side showed 3psi at idle...hmmm...
Passenger side showed zero PSI...hmmm?
Tested the tool and it was still working fine, put it back on the driver's side, rev'ed the motor to a steady 2K RPM and watched the pressure slowly climb over several minutes as it warmed up, from 4psi to 7.5psi.
Put the gauge back on the passenger side, started and rev'ed the motor and got some minor blips on the gauge but mostly was zero PSI.
We presumed at this point that the driver's side had a blockage, though we were scratching our heads a bit at the almost totally zero reading on the passenger side.
So then we had the bright idea that we SHOULD HAVE DONE like 2 months ago. We hit the exhaust cans with a rubber mallet, and found rattling rocks inside the driver's side primary Cat. Duuhhh....
We then separated the y-pipe from the driver's side primary Cat flange and found the surface of the Cat intact, no love there. So we unbolted the pipe from the pre-cat and took the pipe all the way off and found the shattered remains of the Pre-Cat in the pipe on the up-stream side, lots of gray powder and several good sized chunks of that nifty ceramic/platinum honeycomb.
Mystery solved it seems. I'll be taking a chunk of the dead cat to my local Nissan dealer tomorrow at lunch and tell their service people the story and see what they think of it
I really don't want there to be risk of this happening again, so would it be possible to just gut the pre-cats and run them hollow? There are O2 sensors after each Cat, so I'm guessing that's not possible, what do you guys think?
Very very happy my motor isn't blown over here...I need to go email Stillen an apology and appreciation for their suggestion of the failed Cat causing massive detonation.