OEM replacement catalytic converter

[DrZ]

August 2014 Purchased used 2004 Mercury Marauder. I changed many parts on this car having coil on plug (COP) problems which showed misfire codes. I changed plugs and COPs in front of old owners house and drove home. Spent time and fixed everything needed to pass NY state inspection October 2014. The fire wall next to top converter showed me that misfires ruined insulation covering. 2015 October NYS inspection needed. Since July 2015 the check engine light goes on every 500 miles- code P0420 passenger catalytic converter always comes up. I finally get a converter to replace weak cat converter with Ford OEM converter with new O2 sensors-Done! Green light on reader. CA/NY state inspection is a pain in the a$$ but clean air is nice from my daily driver! Shop can't replace converter with used part in NY state since it is illegal. The car from first day of purchase with spark plug and COP replacement ran awesome but the exhaust did show slight black carbon on chrome tips. Today it will go to Bay Ridge Ford for inspection then send the car to WVU for my son.

[lifespeed]

Congrats on the Marauder purchase and getting it tuned up. Putting a used wear-item part like a catalytic converter on your car is a ridiculous idea, it is not surprising the state would disallow it. You probably should have replaced them both, although I do understand economic realities.

[fastblackmerc]

Cats really don't wear out. Probably failed from all the raw fuel being catalyzed from the failed COP(s).

[Mebot]

Today it will go to Bay Ridge Ford for inspection then send the car to WVU for my son.

WVU as in West Virginia University in Morgantown?

Boy, I hope your son has a nice, quiet place to park. Morgantown's roads are not conducive at all for a big car like a Marauder and especially would be wary of driving it and parking it around a college town. just my $.02

[lifespeed]

Cats really don't wear out. Probably failed from all the raw fuel being catalyzed from the failed COP(s).

"Wear" may not have been the perfect word, but I stand by not using junkyard parts for replacement. I wouldn't use junkyard O2 sensors either.

[DrZ]

Morgantown WV is the place and I couldn't agree more about the roads being a problem. The Black 2004 Mercury Marauder passed NY state emmissions test yesterday. I myself replaced the passenger catalytic converter with a slightly used 2004 Mercury Marauder cat. 2 new OEM (green and blue) Motorcraft O2 sensors were installed with new Ford nuts to manifold. I also replaced gaskets between cat and H-pipe with OEM bolts and Ford special nuts. No leaks and no problems with check engine light! I drove Friday from Brooklyn, NY to Morgantown WV and pick-up my son and he drove back to Brooklyn. I bought complete Marauder exhaust from member in Niagara, NY so I have parts I need since I own two MM's. All statements above are 100% correct-the car suffered a COP/spark plug problem in two or more cylinders causing the original to the car catalytic converter to over-heat and fail. It is proven by the condition of the insulation covering firewall on passenger side-it is slightly melted and frayed. Ford bolts, nuts and gaskets are standard over the counter parts. Needed air gun to remove nuts to manifold and cut cat to h-pipe bolts/nuts with 4 inch grinder. Easy job with 15mm swivel impact socket to remove nuts for cat to exhaust manifold. Thanks to everyone for your comments.

[chief455]

good score on that new exhaust from upstate NY ;)
I was tempted...

[DrZ]

Your correct Chief455 that exhaust purchase was a score! Thanks I finally got around to my own car, an original owner silver Marauder. This is car is number two in service lineup. This time I used oxy acetylene and a 4 1/2 grinder with thin metal cutting disc. Much easier but stock H-pipe had severe rust where H-pipe front flange meets tail end of catalytic converter. Converter is perfect with 134,000. Never replaced O2 sensors. I made a judgement call placed new gaskets and bolts without H-pipe replacement. The original O2 sensors stay since this car never showed a code.. Looks like no leaks. Some miles will tell me if I need to use my in original but used H-pipe.