Good afternoon guys... I own a 2009 XK with approx 30k miles on it. It’s well maintained, upgraded the complete exhaust with Velocity 200 cell stainless steel cats and complete stainless Larini club sport exhaust. I’ve noticed a strange smell during hard acceleration and a sluggish return to idle response. I’m suspecting clogged cats but I’ve had them less then 10k miles. Any thoughts?

 

Are they ceramic or spun steel? Another member here had a similar problem with 200 cell spun cats as they had melted.

 

Hey Many! I think I mentioned to you the potential issues with high flow cats , as I have had. Can you easily take them off to see inside ? If you had an r car there is an easy way to tell if they are getting clogged by monitoring boost, on your might have to take a peek inside the actually cats
Mine failed completely at 7500miles less than a year since I got them

 

Yeah, I’m going to my muffler guy and have them inspected this weekend

 

Leaking injector ?

Unburnt fuel entering the cat then igniting ????

Running too rich ?

 

Don't mind me asking how do you tell if cats are bad through boost, this could help me.

 

Bad thorough boost ?? As in you believe they are overly restricted as in clogged ?

 

I keep blowing a 430 code , swapped O2's around and still 430 so they are fine, trying to eliminate things , if you can tell you have a bad cat through boost gauge I could do this? But what am I looking for.

 

I can almost guarantee melted cats. There is a lot of junk out there, even name brand cats can and will fail especially behind supercharged/turbo charged engines. There is a reason some cats cost $90 and others $500. Stock or none is best in almost all cases.

 

I just got a 430 code also, so I may be in the same boat.
I'll compare my upstream O2s to my Downstream O2s live-data first, see if anything straightens out.

 

Well you need to log boost at wide open throttle in second gear for example. You simply compare it to stock or what your stock boost should be. Any restriction in exhaust will cause boost spikes. For example when my catsmelted boost went up by 2 psi

 

I don't know what my boost is supposed to be, so that's no help.
What I DO know is that if the downstream O2 sensor looks alpha wavey like the upstream does, your cat is probably toast.

 

I know what it soposed to be . Just need you to log if you have a Bluetooth OBD adapter and send log to me

 

if you know why don't you just let the rest of us know?

 

I think its 13 psi.

 

I look at logs all the time so can probably spot it better. I look for boost spikes outside of normal for that particular engine . I have logs from different customers cars to compare to. I would need mid to 100,% load at WoT to look at . Another tip on a sign of clogged catalytic converter is sound, usually the exhaust becomes quieter the more catalytic converters are clogged

 

Okay, so where did my upstream O2 sensor go on bank 2???

 

Rumour has it that new downstream O2 sensors, on bungs, have sorted the issue before; that is, if the cats aren't toast.

 

Can do an oxygen drop-down test to check the cats. See how long the downstream takes to react to input from STFT changes. Cats should follow 6-10 seconds behind, manifested in the downstream O2 sensor graph.

But back to WHERE'S my Upstream sensor? It's not listed as supported in Torque. The OTHER bank's sensor is there and operates.