Anybody have a link to one of those catless down and intermdiate pipes?

 

No, other way around. The sensors closest to the head are the check, the ones furthest away are the ones that control the fuelling.

The sensors on these cars are of a different style to just about everything else out there ( Land Rover also used them) so the threads are different to prevent putting the wrong type in.

 

Yep, please see the first post in this thread

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So, then I wonder if the "O2 cheaters" mentioned earlier in this thread won't even screw in... ignoring if they even work, I wonder about that BTW. If they do work, that would be an easy workaround.

Also, so this leads one to believe Andy's suggestion of mounting at least the downstream upper O2 sensor after the under car catalyst might solve the CEL problem? If this first set does not impact fueling, then we just need to be interested in tricking that O2 sensor following the upper catalysts into thinking there are upstream catalysts.

Are we 100% certain that the upper two O2 sensors serve no other function than to validate that the upper catalysts are present, and they do not impact fuel mode, mapping, etc?

If yes and someone had the time, energy and desire, this would be an easy test to unhook that downstream upper O2 sensor, install a second O2 sensor after the under car catalyst, and just extend the wiring from the downstream upper O2 sensor to this new added O2 sensor to see if the car then trips any codes or makes the car run any differently. If not, then that's the solution to eliminating the CEL and fooling the ECU to think the upper catalysts are still there.

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On every US car the first set of oxygen sensors, clisest to the head, are the ones that control fuel mapping. Even BMW and Mercedes, as well as the Japanese nakes do it that way. Its weird that Jag does it backwatds since the exhaust that passes through the convertors will be cleaner and leaner than before tge cats, give false readings of being too lean and telling the ecm to make it richer, causing poor mileage, poor performance, and overheating cats. Jag cant be that nuts can they, lol.

Heres the part number for the catless downpipe:

CBC6373

Do a google search on it, many results listed.

 

I believe the first set of O2 sensors also detects proper functioning of the air injection, can that be confirmed? If so, is it the first or second O2 sensor that detects the air injection?


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Well, this IS NOT "any American car" and is not a Mercedes,a BMW, nor a Ladha.

On an X-300 Jaguar, the downstream lambda sensors control the fuel trims. It was possibly done that way so that two different mapping schemes were not required- one for the European versions using only two Lambda sensors post cat and another for the four sensors required in the US cars.

You know, I am not a tree-hugger BUT with no apparent improvement in performance, I think it is irresponsible to remove pollution equipment from a car. Those who think it is OK will justify their actions all sorts of ways, but it is sort of like throwing your trash out of the window onto the roadway! Not that I have not done exactly that on a rare occasion, but responsible citizens of planet earth just do not do that!

 

SNG Barratt - The Ultimate Jaguar Parts Specialist

I got mine from SNG very inexpensive although it takes a few weeks to get them shipped from the UK. I've never ordered anything from Jaguar Heritage although its an excellent resource for finding parts and part numbers.
As to removing equipment, I waited until mine rusted out and I still have two working under floor cats. My car is officially listed as a California engine variant, which I guess is why it had 4 cats. Besides if the peoples republic of massachusetts says its ok, who am I to argue......................

 

Here is the O2 extension type "simulator" that has been mentioned, but who knows if it works in our application plus you would have to actually remove your catalysts to test:





Something like this is interesting too, building an electronic simulator circuit for the downstream O2 sensor? Have no idea if this would work on ours, but surely the least expensive option if so.


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I'll actually be trying it sometime in the next month or two. Because I live in Massachusetts my 97 is no longer subject to emissions testing. I no longer have any cat's as they rusted out. I replaced the exhaust down pipe and have had the CEL ever since. Our O2 sensors are 14mm as far as I can tell, most seem to be 18mm so it's harder to find 14mm spacers, I have some and will either try it myself or have it done. I don't have the wrench to get the downstream sensors off, although it appears to be very easy if its on a lift. This is the down pipe I used:

The CBC6373 Exhaust downpipe is available from Jaguar Classic Parts in the United Kingdom. Part suitable for use in XJ Series from (V)720125 to (V)812255 (X300), XJ6 (2.9, 3.2, 3.6, 4.0) from (V)500001 to (V)667828, XJ6 & XJ12 from (V)667829 to (V)708757 models.

 

The non-catalyst intermediate pipe NNA6757BA is no longer available from Jaguar Classic parts. The non-catalyst downpipe CBC6373 is still available.