Several weeks ago my 91 XJS V12 suffered the classic Marelli Ignition failure. In addition to destroying my cap, rotor, wires, coils and front catalytic converters, it apparently also melted the rear ones too. My question is: Can the rear ones be eliminated? Being a 1991, it's emissions test exempt in Massachusetts. And if eliminated, will it run better with less restriction? Insurance is covering the repairs.

 

You could knock out the remaining converter material and reinstall the empty shell.

Ort you could do a search to find used converters. Since it is always the right rear that melts the worst, I ended up gutting my right rear after a Marelli failure. I have not shopped for a used one yet and I am getting tired of buying replacements at several hundred dollars each time.

 

Each time? How many times has your Marelli ignition caused a fire, then?

 

Yes. Nothing bad will happen, other then the air being a little dirtier



If you go to a muffler shop to have them removed you *might* run into resistance, though. Massachusetts might not care but, technically speaking, it's a violation of federal law to remove the converters. Some exhaust shops worry about this more than others.


Better? In terms of power? If they're clogged you should feel a difference by eliminating them. Otherwise, I doubt you or the car will notice any change.

Cheers
DD

 

I had a V12 sedan that I drove with and without cats. Absolutely no difference in terms subjective performance. I didn't measure the 0-60 times before and after, but by the seat of the pants meter there was no difference between with cats or without.