Noticed my car today while cold and parked idling in the snow that one side was blowing crisp normal exhaust and the other was painting the snow brown with something, wasn't blue or jet black

Two questions..

1) Assuming the throttle stuff was set properly by the shop and my new coils/amps are functional what normally causes one side to blow soot? I'd imagine the air pump is functioning at this time during cold startup to maybe one side is clogged...

2) Are there any reliable exhaust sensors one could purchase to see what is going on in regards to how balanced the engine is? I would imagine two EGT sensors would give valuable insight.

Let's start with something easy:

Brown? Sounds like rust.

Take 'er out and give 'er the boot a few times to blow that crap out. Don't be bashful.

Years ago, my first jag, an XJ6, liked to accumulate rust inside just one side of the exhaust. Never could figure out why just one side since it was a single exhaust that branched out into dual exhaust. Anyhow, I'd romp on it a few times , all sorts of brown gunk would blow out. Then clean exhaust....just little wisps of light gray.

Repeated as needed every few months



Cheers
DD

I agree.

Dont overthink it, DRIVE it, the RED line on the tacho is there for a reason, and if you are brutally honest, the V12 LUVS the revs like no other engine I know.

As Doug said, repeat as needed, usually whenever you start the thing, so probably DAILY.

Also, don't forget that the snow is so clean and white here in Vancouver - so that makes a little bit of soot look like the worlds falling in.....

Can't take mine out in the snow yet as it's jacked up waiting for caliper seals and shocks/springs to arrive, hopefully get here by Monday then I can test )

We should meet-up for a coffee as we appear to be close?

A local! hah! small world, I'm in west van though I'm down a vehicle so not taking the XJS out in the snow by choice I've done as Doug and Grant suggest and floored it up and down the hwy at the red line it seems to like that.

Italian Tune UP.
Keep it in 2nd gear and give it loads of beans for 20 minutes.

hope the trip down #1 fixed it....

I pm'd you for a meet-up sometime so the cats can meet 'n' growl