Removing Catalysts - Cliff Pope
You have twice recently answered readers' questions about removing the catalyst on cars of about 1993. What precisely are the rules on this, and has anyone any experience of a) MOT testers' reaction, and b) cars running, performance and fuel consumption after modification?

You said reduced back-pressure might be a problem, and in one case recommended an intermediate silencer in place of the catalyst, in another re-chipping.
Should the Lambda probe be welded back into the pipe/silencer, or taped up out of the way but left connected, or unplugged?
Obviously if avoidance of a massive charge for a new catalyst on an older car is the motive, then the simplest/cheapest option is the best. What are the consequences of simply replacing the pipe but doing nothing else?
My car is a 1993 Volvo 240. Any of a big range of exhaust pipe/silencer options would fit, if fitted in entirety.
Cliff Pope
RE: Removing Catalysts - honestjohn
Dear Cliff,

You can't remove the cats of any post August 1992 cars for which test data is in the advanced emissions system computer data bank. This was explained in my answer but the subs took it out. Between August 1992 and the end of July 1995 exemptions were made for cars for which no test data was available. The Vitara is one such rare car.

HJ
RE: Removing Catalysts - Peter Almquist
Are there other rare cars that you know of, forexample big Mercedes or BMW?
Thanks
Peter
RE: Removing Catalysts - Arthur Rabe
I have a 92 Mercedes 230E, at the moment in perfect working order with 62000 miles on the clock. The CHIP SWAP item in last weeks telegraph motoring supplement got me thinking about some time in the future when the catalyst might need replacing. I always assumed that once fitted to a car, the car would have to run always with the catalyst in working order. My previous car was an Audi Avant Diesel that gave 16 years service over 230,000 miles. I hope to run the merc for some years, and the question of catalyst renewal will almost certainly arise. So the possibility of running without one is very tempting. Any information would, no doubt, be interesting to myself and a lot of other people.
Arthur Rabe
RE: Removing Catalysts - honestjohn
Dear Arthur,

Pretty simple. If the car is a 92J you can remove the cat. If it's a 92K you can't.

HJ
RE: Removing Catalysts - Cliff Pope
Thanks John.
But you said back in March that it would be feasible for an M-reg Montego. Is that a rare car too then?
Where can one consult this list of exempted cars please?

Cliff Pope
RE: Removing Catalysts - honestjohn
Dear Cliff,

You need to look at a print out of the cat testing data from the Vehicle Inspectorate. If a car first registered between August 1992 and July 1995 is not on the list, it is exempted from an advance emissions test. If it is on the list, it isn't exempt.

HJ

 

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