Catalytic Converters

[alamn2]

Last MOT, the car wasn't passing on the right exhaust but on the left side it gave the correct readings ,, the tech did say the right side seems hotter and may be blocked at the point of the CAT.

A week on and iv not done any heavy driving the right side cat is now blowing or an area around there the rattle is louder on cold and I can see smoke puffing out from cold but as it warms up it quiets down, iv only driven abut 20 miles since the MOT.


Questions:

Is it possible to Decat an Xk8? or is it betetr to replace the cats.. now to replace the cats anyone with experience on complexity and effort? old bolts are pulvarised so will it be a cut and weld.

Is it ok to just replce the 1 cat is should i be doing both

[alamn2]

https://www.icloud.com/attachment/?u=ht ... z=74592238

the quick video can be found above , its the cat on the far side thats blowing

[Andy P]

Hello alamn2,
As far as I know you have to have the cats with all the cells inside to do their thing to the engines exhaust gases as they pass through the catalytic converter,you have an oxygen sensor on the inlet that reads the gases coming in from the engine and another that reads the gases after they have gone through the cells of the cat where there is another oxygen sensor that reads what the change was.This is what directs the ECM to add or subtract fuel to the mixture that is being fed to the engine so that it will run at it's optimum efficiency.
If your looking to replace the cats I would do both but not really necessary as long as you replace with the same type.
Here's a link for some cats:
https://www.xk8-parts.com/2013/06/great ... onvertors/

A couple of years ago I had the drivers side cat blowing like yours due to a hole caused by corrosion,I used the exhaust wrap that the custom guys use for a temporary fix with the intention of replacing the cats later on.
The wrap is still on after two years,the wrap comes with stainless steel cable ties but I used some wire that I had lying around to secure the wrap.Might be worth a try.
I wrapped both cats just to even things out so it didn't look out of place(I like things equal ).
Here's a link for the exhaust wrap:
https://www.ebay.co.uk/sch/i.html?_from ... p&_sacat=0
Hope that helps a bit.
Take Care.
Andy

[nrandlexj40]

On a similar note - I'm going to be replacing both Cats on my 1996 Coupe as they are blowing very badly.

I notice that 2 options are available - homologated and 'non-homologated'
From what I understand - post 2001 cars have to use homologated cats and earlier models don't....

What are the pros / cons of the 2 options?

[mike020150]

Homologation is about ensuring (in this case) that emission standards are adhered to. A non-homologated cat could be a universal version, not specifically designed for the XK8 and therefore, it may or may not produce exactly the same emissions as one designed specifically for the model. As emission standards tightened, from 2003 onwards it was deemed important to ensure that the emission standards achieved on the original tests would also be achieved when replacement cats were fitted. Mike.

[J44EAG]

I have non standard, fast flow, 200 cell sports cats on my MY04 XJR. It seemed a good idea at the time.

Yes, I can get an MOT test but have to rev the car hard for two minutes prior to the gas test. The sports cats help the car go like stink but stink is the operative word when the cats go cold on the MOT ramp. I watch the cats light up again on my Torque Pro app on my Android phone which links to the car via an ELM327 blue tooth chip. When the cats cool, the emissions go off the scale. Hotted up, that is a different matter.

OK, I live with the condition but it is not recommended. Stick with genuine Jaguar OE cats appropriate for the year of your car whenever possible.

Mike K

[nrandlexj40]

Thanks for the info. It would appear that homologated cats are the way to go....

I'll continue with the restoration and hopefully we'll be up to MOT stage in the next month or so !!

[alamn2]

Hi sorry i disappeared

i bough two new slot fit replacements , replaced them 6 months back, on the drive but with covid car not moved much.

one had a hole in it , took for an emissions test failed badly on both sides even after having car on for an hour and adding cataclean , could it be the cats or the sensors ?

[alamn2]

here's the link to the pair i picked up on ebay

https://www.ebay.co.uk/itm/182750740215?ul_noapp=true

[mike020150]

Unfortunately, there isn't enough information in your question to enable a confident diagnosis. Poor emissions performance can be caused by anything from a time expired spark plug, to a failed head gasket or anything in between like a perished vacuum pipe or dodgy catalytic converters! Under these circumstances, the most cost effective approach is to have a proper diagnostics session before spending more money on spare parts hoping that someone's next guess will land on the right solution. Blindly changing everything is a very expensive game compared with paying for an hour's diagnostics with a Jaguar specialist who has Jaguar-specific diagnostics kit. Mike.

[alamn2]

Unfortunately, there isn't enough information in your question to enable a confident diagnosis. Poor emissions performance can be caused by anything from a time expired spark plug, to a failed head gasket or anything in between like a perished vacuum pipe or dodgy catalytic converters! Under these circumstances, the most cost effective approach is to have a proper diagnostics session before spending more money on spare parts hoping that someone's next guess will land on the right solution. Blindly changing everything is a very expensive game compared with paying for an hour's diagnostics with a Jaguar specialist who has Jaguar-specific diagnostics kit. Mike.

Appreciate the direction but for this project was I trying to learn and maintain this bird myself. But Yiur right some things need to go to a specialist but I wanted to iron out the obvious .

So I hooked a diagnostic the reading for oxygen sensors is 19 but one sensor has voltage of 0?? What should be the o2 reading at idle and surely the voltage should be >0 on both no MIL illuminated

[mike020150]

If you check the MoT emissions test readings on a certificate, it gives the lambda range as 0.97 to 1.03. Certainly, 0.0v suggests there's a sensor or wiring problem. Jaguar sensors are expensive and difficult to find at sensible prices. However, don't be tempted to try using one of the many so-called 'universal' replacements for sale online. They just don't work well in our cars. Mike.