I'm mainly posting this for others to find when they do research. One more clogged catalytic converter story.

2008 XKR with just 70K miles.

Under acceleration at 4K RPMS the car would go into Restricted Performance mode and the CEL came on. The codes were for missfires on all the even cylinders. From reading here I guessed it was the cats, but the mechanic wanted to do his own diagnostics. They replaced all the ignition coils, no change. They swapped coils around to see if the missfires followed, they didn't. After 3 weeks they decided to put on new catalytic converters, and what do you know it worked. The car runs and sounds much better now, no codes.

They cats they installed are these Magnaflow bolt-on units:

https://www.magnaflow.com/products/5...t?aces=6596083

 

Aren't all cats warranted for like 100,000 miles? It's mandated by the EPA or something.
I hope you didn't pay much.

 

I didn't pay anything

I bought the car about a month ago. The day I drove it off the lot, I floored it and it went into Restricted Performance mode. #jaglife

So I contacted the dealer, they said bring it back and they would make it right.

First they replaced the battery.

Then they did a full synthetic oil change (not sure why)

Then they replaced all the coils

Then they put on the new Magnaflow cats

It took 3 weeks, but they didn't charge me anything. They got a very favorable Yelp review.

There was one hiccup. After I got the car home I started hearing an exhaust leak. I took it to the local exhaust place, they said no matter how much they messed with the slip joint at the cat they couldn't get a good seal, so they welded them up. They also didn't charge me anything, I will be taking the 68 to them for a new exhaust soon.

 

Lucky you finding a cooperative exhaust place.

I'm trying to replace my CATs now and the exhaust place doesn't want to do it because I purchased the CATs from somewhere else.

Another shop is telling me they would charge 3 hrs to do it.

Really don't want to do it myself with just jack stands.

 

Three hours is pretty fast. Heck, I spent over an hour getting the o2's swapped out.

 

Really? Does the whole exhaust have to come down for the O2s?

From what i read removing the exhaust is simple and quick, maybe they were just exaggerating.

 

Yeah, muffler, then mid pipe, then each cat pipe. It's kind of a pain in the ****. because the Jaguar pipes use slip joints instead of ball flanges like most manufacturers.

OP's mechanics are gonna have a tough time getting the mid and cat pipes down together.

 

We'll burn that bridge when we come to it.

From here on, I am the mechanic

 

It's a mother to get the mid loose from the down pipes. I ripped a couple wires loose by the rear mid pipe hanger when the hanger grabbed them on the way down on mine when I did it the first time.

 

Thanks for sharing.

I've pretty much lost count of how many supercharged Jags & Range Rovers i've seen or heard of with choked cats now.

This is going to be more and more common in the future.

 

Why do you think this is?

I think mine are too. Once I get them out maybe ill cut em open and have a look. I only suspected bad CATS after my PCV valve failed, burned a ton of oil, then ran seafoam to clean everything out. Since then I've had hesitation around 2000 rpm but no noticeable loss of power or performance.

How hard was is to disconnect the vacuum pump and active exhaust in the back?

 

It's just a pair of small vacuum lines that need disconnected. No biggy

 

@Beau M: how do you like your xkr in white? I'm looking at a very clean white over black vert, still not sure about the color. Yours look very nice as a coup.
I need convincing,..........................

 

I love it. It was my #2 pick when shopping. It hides dirt really well, the opposite of a black car. I know this is a crappy picture, but it's been raining here the last week or so, and I've been commuting in it every day. The car is filthy dirty, but from 10 feet away it looks fine. The white hides swirls and scratches etc, it's very easy to maintain.



Here's a couple pics from a local get together when it was mostly clean.

 

One reason can be a car which has run for some time with bad fuelling / fuel trims but not so bad as to flag codes. Gradually damages cats.

Or not going CL (closed loop) as soon as it should - will inevitably run rich (to prevent engine destruction) and damage the cats.

I like to check at least annually that the OBD values are good (I eyeball IAT, ECT, and so on, too) regardless of the MIL being off (and thus no emissions codes).

 

Also, many short trips with gunk building up vs. long journeys where heat can burn off excess crap.

 

My theory, and it's just a theory, is that ALL cars are suffering from choked cats to some extent, once they get some miles on them, or if they are not driven hard enough to blow out the crap that's building up in there.

I know of two naturally aspirated XK's which also had choked cats, it's not just affecting the supercharged cars.

The thing is, the problem is less apparent on the naturally aspirated motors, in your day to day driving.

Because the supercharger is pumping a fixed amount of air into the engine every revolution, if the exhaust is choked up and can't get rid of the waste gases, well there is always more air coming in regardless so you have a squeeze, which leads to the misfires .

Whereas with a naturally aspirated engine, it's having to suck air in, and if it can't, well it won't. In extreme cases you get the misfires on a naturally aspirated motor, but even in mild cases it's coming on the supercharged motors, because of the air being forced in to the cylinders.

 

Interesting. The first set of CATS I choked up occurred when we were revving the engine to near red line at the Montreal F1 Saturday night party.
(If you have never been here, put it on your list. The crowd and the police together are motivating all cars on the street to make a little noise and smoke)

Yes, they were glowing red.

So did I choke the cats... or just melt them??

Incidentally I'm in Sydney tonight... looking forward to Vivid.

 

My guess would be they were part-choked before you did that and could not cope.

 

My buddy keeps telling me to go there too. He also says its a good time. June 8, I'm highly considering it ....