V8i cat removal

[defenderdan]

I have a 3.5 V8i disco. I want to remove the cats by either cutting them out and welding in fresh pipe, or simply open the box and remove the innards then weld back up again. This is because they have broken up inside. Can i just do this or will it cause ecu issues or anything like that?

[G]

No doubt someone will correct me on this but i'm sure that you can remove the cats so long as you keep the lamda sensors fitted. Only prob is the MOT, if the new MOT system says that your vehicle has cats fitted then they should be there (after 1992 I think). G

[tintin86]

me thinks your right about the cats being fitted but i think you will find that this ref to vehicles after 1993 (K)this was the case  when i was a mot tester 10 years ago hope this helps :) as for ECU issue's as long as you refit the lamba sensor it should run fine

[defenderdan]

Cheers people, that's what i wanted to hear :D

[Dave88]

Not sure about the 3.5 but if you take the cat out of a 3.9 you need to change a resistor somwhere so the ecu adjusts for the lack of cat. 470 ohms rings a bell but I can't remember if this is the before or after resistor.

Dave

[Range Rover Blues]

On the Lucas Hot Wire (also used on the 3.5 Dsico) then you're talking about the tune select resistor.  The easiest thing is to leave it as is, leave the Lambdas in and the ECU knows no better.  Otherwise you can remove the Lambdas and change the TSR to tell the ECU there are no cats fitted.  You might still get an error code though, for some reason I do at the moment :?

[MartinV8]

I have had no cats on the 3.9 disco for a couple of years as I have a SST Sports system. I retained the lambdas and it ran great however one has recently packed in and rather than replace, I changed the tune resistor from white to green. Runs great, just waiting for MOT time. It's passed on gas without cats but might not without any lambda feedback. We'll see, got another 8 months yet!

Martin