Wow- glad you got it fixed! It's always a shock when power is suddenly regained and we become aware that it must have slowly and surely decreased over an extended period without us realizing.

One thought- it's not normal for cats to become clogged at 100K miles (or any threshold) without other engine issues being the root cause. I don't remember reading about any oil consumption issues nor the use of fuel additives which are common causes in other cases, nor any engine mods that would induce such problems.

Did I miss something?

 

Like I said
My car had 160,000 k,s went alright first thing I did was replace the cats and o2 sensors front and back then a tune to stop the red-light on the dash and codes coming up she should be good for another 160,000 k,s
In the old days before cats we used to remove most of the emissions stuff so the car would actually perform now they fine the hell out of you if you do that
at least its sorted now Cam and the new bits you installed are new so cant hurt

 

Indeed good that the last thing has been found (next to the failing fuel pump).


But, no time to cheer yet imho (well at least for a couple of days ;-)), it is important to find out why it happened to avoid it from coming back again, as I don't think it is normal to get such amounts of carbon on the piston and getting a clogged cat.

 

A slightly hesitant hooray - hope it stays fixed!

 

I think a round of polite applause is in order

In the link given recently to the Ford forum, it seems
to boil down to the demands made on the cats by
blown engines. The posters there made a point of
using top quality metal internal construction to
avoid reoccurence soon after replacement.

 

Yes I would like to know what caused this, and how to stop it from happening again.

A few observations first;

All of the intakes that have been opened up on these engines, have shown a black sticky residue, on the back side of the throttle body butterfly, & the inside of the induction elbow to the supercharger.

This is where the PCV line is, as well as the EGR.

Charlies photo of what get's caught in his catch can says a lot https://www.jaguarforums.com/forum/x...esting-130689/

So that crap is going into the intake. I have ordered a catch can & will be fitting it up.

I am also wondering about the EGR valve. Is it blocked up with crap & open all the time? Can I somehow block it off or put a restrictor plate in there to limit the volume of crap from the exhaust getting back into the intake?

Getting the EGR off to inspect it is a royal PITA, but I think it might be worth looking into.

My theory is that once you get build up in the intake and the cats have aged a bit, it turns into a vicious circle which snowballs.

Slighty choked cats cause the engine to run rich, the EGR transfers that soot to the intake, oil vapour from PCV enters intake, get's burnt during combustion, re-enters the intake via the EGR, adds more crap to the intake, cats get slightly choked up, which causes the engine to run rich, which adds more crap into the exhaust, which chokes the cats further, while being pulled into the intake via the EGR, that fills the intake with more crap, etc. etc... and eventually the whole engine and exhaust gets choked up to the point of where I ended up.

The big clumps of carbon/crap that we saw on the pistons are likely to have been transferred from the intake to the cylinder when I used that can of upper engine cleaner, it did shift the crap out of the intake, but just moved it to the cylinders, but there wasn't enough cleaner to get it out out of the cylinder.

Just my theory at the moment.

So what to do?

Catch can first of all, from what i've seen it will reduce a lot of the crap that gets into the engine.

Then I need to have a think about the EGR. Blanking the EGR completely does not seem to be an immediate option, as it will throw up a code and the check engine light. For the amount of work needed to get the EGR off the engine, i'd want to be sure that it never has to be done again...

What else could cause so much crap to built up in the engine?

 

The guys who put in the cats do a lot of performance vehicles, they told me "these ones will never block up" I don't know if that's because they have bigger cells or because they are metal instead of ceramic, but either way it does seem the metal ones are the way to go in boosted engines.

The cats that came off the car do not really show any signs of damage, the honeycomb structure appears to be in tact and they don't rattle when you shake them.

But what you do notice, is that very little light passes through them. Put my super-bright LED workshop lamp at one end and you can just barely see the light at the other end, not sure I could even get a photo of it, it's so dim...

Will take some photo's of the old cats and post them up here.

 

The black photo is what I could see through one of them, couldn't even get a photo of the light passing through the other one...

 

One presumes you guys "down under" run unleaded gas only?

 

Yep, unleaded, I only run 98 RON (and only 100 RON when we were back in Europe) and this car has never been run on an Ethanol blend in the time i've had it either.

 

An ounce of TC-W3 oil mixed with every 5 gallon of gasoline may help with the carbon cleaning on top of the piston top.

 

Pic of the #1 piston top today, so the carbon clean did a fair bit by the look of things.

 

I'm still curious as to the root cause of the contamination. Being that 98 and 100 RON fuels (would be labelled 93 and 96 AKI if they were available here) are well above the Jag spec of 95 RON, I wonder if the octane boosting additives might be a contributory factor?

Fuels above 95 RON are a rarity in North America, with 98 occasionally being seen. 100 is unheard of outside of 'racing fuel' locations.

 

Never used 95 ron (maybe once or twice in 260Kmiles), only 98 or sometimes higher and never seen anything like this. My best guess would be some richness, or imbalance of fuel injected, causing the buildup in the cats, assuming no additional additives where used as you suggested earlier.

 

Erm... would you consider bottles of octane booster an additive?

EDIT

Let me explain further.

Back when the car was in Europe, I ran it exclusively on Shell V-Power 100 RON, which was available in Switzerland & Germany, where I mostly was. The car ran great on that stuff. Got brilliant fuel economy on the highway, and seemed to make good power, based on the 1/4 mile results from Santa Pod in the UK.

When we brought the car to Australia, it just never seemed to run as nice on the local 98 RON premium unleaded. I was using Shell V-Power here for the first 6 months and it never felt as good as the 100 RON V-Power in Europe. I did use octane booster to try & get back what I was missing from the 100 RON. Can't be all that sure it made a positive difference, I did see (slightly) higher ignition advance but never that same goodness from behind the wheel.

So what are the odds that a few bottles of octane booster choked up my cats?

 

None. Cats choke up from sulfur in the fuel. They are done at 100k miles. I disagree with anyone who says otherwise.

The only shot you have at getting extra life from them is to make sure they get hot enough to catalyze every time you drive the car.

 

I've been told by many people that "cats don't last forever" and frankly when you look at the ones that came off the car, it actually appears to be tiny pieces of ceramic that have chipped off the front of the honeycomb and are blocking it up.

The car is definitely running leaner now with the new cats, I can see it on the tailpipes, they've gone from sooty black to dry dark-grey with a faint tinge of brown.

Looking at the LTFT's, STFT's and AFR via Torque the numbers are all over the place now, and it really does seem to be too lean in places.

For example, holding steady 2000rpm in neutral the AFR goes to 15.3:1 and after a minute or so it goes back to 14.6:1

The LTFT's at idle are +6% and +4.2% with the STFT's bouncing around all over the place. Holding the 2000rpm the LTFT's go negative and the STFT's go even crazier, the min/max on Torque is showing -25% & +25% for the STFT's, I never noticed that before...

The min/max for the AFR is showing a max of 18:1, not sure when that happened...

 

Did you clear all the learned values (e.g. hard reset) after changing the cats?

 

The battery was disconnected while the guys worked on the car so I thought that would have done the same thing...

 

Alright I got to a dyno this morning. Not the same dyno as previous runs, but I was more interested in checking the AFR's than trying to get a power number.

Long story short, the fueling looks fine.

Consistent 14.4:1 AFR measured by high-speed wideband in the tailpipe. Tried part throttle cruising at various rpm, also half-throttle accelleration without going open loop, all bang on 14.4:1

Full power run saw the usual enrichment down to 11:1 at 6000rpm.

I'm not going to say what power it made; different dyno to usual so it's not an apples-to-apples comparison. This guy told me everyone complains that his dyno reads low.

But

I did get to the drag strip on Wednesday night, only got one run because a storm came in, but the car trapped 106.2mph which is pretty much what it always did in the past. So it's back to it's old power levels.

I would have expected higher, but that's what I got. Might just be that I got so used to the car being down on power, the "recovered" power felt like more.

What the bloke did tell me is that with brand new O2 sensors the outputs are very sensitive and jump around a bit, which in turn throws the STFT's into a bit of a flap. Old O2 sensors are slower to respond and give more stable output. He also said not to worry too much about the OBD values, the real measurement at the tailpipe confirms the fueling is fine.

No closer to figuring out why this all happened, but it seems resolved, for now.