I have a 97 XJ6L with about 107k miles. The check engine light came on and while i haven't had the codes read, I'm pretty sure its the cats, its happened a couple of times in the last two years. Usually a long fast drive 120-150 miles has been enough to "clear" them out and the light goes off. Not this time. I have read through most of the threads including Doc's. I was looking through Jaguar Heritage and saw there are country versions, Japan?, that do not appear to have front or rear cats, just straight pipes and resonators, did i read that correctly? Since I no longer need to meet emissions requirements, I was thinking of pipes and resonators with the four O2 sensors still connected. Does this sound doable without having to change ECU's or anything else?

 

I have no idea, but am interested to hear as our catalytic converters all eventually plug up and will need replacing, or.....


Would love to get SS headers too if anyone in the US were to make some like the ones we've seen discussed here:

https://www.jaguarforums.com/forum/x...s-x300-114521/


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I think it's doable.

You just have to fake out the post-cat O2 sensors if you don't want the CEL to trigger.

I plan on trying to remove the clogged up cats in the next few weekends from a 96 XJR I'm refurbishing. I'll see what happens.

Anyone have tips on building a custom exhaust system for an XJR? I was reading not to go true dual pipe due to loss of backpressure and boost. The car's exhaust system is all banged up and full of holes.

 

Will be very interested to hear how your project turns out.


Where are you located in NC? I am in Sanford, about 45 min SW of Raleigh.

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I got another reprieve from having to do anything. I took it down to my mechanic and he read the codes 1448 and 0430 and then cleared them on Friday. No CEL since, so i guess the long run and a bottle of Techron with Sunocco 93 worked.

 

Yesterday I had my rear cats removed. I had many holes at the Y pipe and the pipes in front and behind the cats were all rusted out. Additionally the hanger on the rear suspension mount had rusted off. The replacement was a single pipe back to a new Y attached to the under seat muffler and then back to the resonator. The resonators and mufflers are original and still solid. about 12-18 months ago I had removed the front downpipes with cats and replaced them with straight pipes, no cats. These are OEM Jaguar pipes from some part of the world that doesn't require them. I still have the four O2 sensors and was going to put spacers on the rear ones, but found out they are not standard size 18mm, but 14mm. Besides sound better and not having to worry about fumes in the car, it also eliminated some knocking over bumps as the old pipes must have been banging around without any hangers. For those wondering, I'm in Massachusetts and am exempt from emissions inspection. I do have the following codes:

P0158 Oxygen Sensor Circuit High Voltage (Bank 2 Sensor 2)

P0300 Check Engine Light Code Random/Multiple Cylinder Misfire Detected

P1314 Misfire Rate Catalyst Damage Fault - Bank 2

 

I just had my downpipe cats replaced with a pair Magnaflow 59905. They fit well, no flow restrictions, no codes generated, and passed an Albuquerque emissions test.
That part of my exhaust is good.
Now the bad. The previous owner removed the under floor catalytic converter and used an X pipe in place to create a true dual system, no problem there either. Problem started when I had exhaust shop remove the factory resonators. Now is waaay too loud and sounds terrible in the mid range, good at idle and above 4000, but from 2000-4000 is horid. Part of the noise problem may be that the previous owner replaced the mufflers with Edlebrock TruFlo mufflers, which were know to flow freely and also were pretty loud. I will have to do something soon about the noise because it is terrible.
As far as loosing back pressure from going full dual, that is bunk. Back pressure is essential for turbo setups, not so much for supercharged. You may notice a slight drop of boost pressure, but that is no problem. Good airflow is desired, both in and out. Boost is pressure, higher pressure means higher intake air temp. If you lose a bit of boost pressure due to low back pressure, no worries. The airflow through the engine will be improved and at lower inlet temp. Plus Plus