Hello, recently I have began driving my 87 xjs he quite a bit more often and one day had it idling in my driveway with my garage open while I was moving some things around. The exhaust was blowing in direction of the garage. The fumes from it where quite intense and would make my eyes burn a bit. I assume it may have been that way for a while and just noticed it. The exhaust is barely visible so I never thought it ran rich. It is a catalyst equipped us model with them intact as far as I can tell without disassembly and visually looking at the ceramic brick. The rest of the emissions equipment is present as well. I'm not sure where to start looking for the cause. Could the ignition timing be off?

 

Was the engine 'warming up'? Or was the car already at operating temperature?

 

Not warmed up fully but had been running for about 5 min at the time.

 

Cat function can be checked based on temps using an IR thermometer. Is the cat up to temp? Is the downstream temp higher than the upstream, confirming the cat is working?

 

Firstly, letting these engines idle doesn't help much The V12 is there to be driven. Give it an Italian tune and then give it a smell... I assume it is just the standard cold start enrichment. When drivrn carefully, the cats 'clog' and it stinks a long time...

 

I'll try that thanks. I never really have gave it a proper Italian tune up, speed limits and all. It rarely sees over 3000 rpm so that could be a factor.

 

This is something I have trouble with, too. I gather an Italian tune needs sustained high revs, which is hard. If there's an empty onramp or uphill road, I can drop it into second and hit the kickdown, and can manage to get the revs to top 5,000 if I'm lucky, but run out of road very fast, or end up going at licence-losing speeds.
Usually both....