I have a Jaguar XJ6 4.0 X300 on a 1997 plate. It is due for its mot soon and it always seems to fail on emissons. Is there anything I can do to reduce the emissions and increase the chance it will pass the emissons test ?. I have heard that there are some products you can use like Cataclean catalytic convertor & fuel injector cleaner. Any suggestions would be greatly appreciated ?.

 

You can remove the O2 sensors and soak them in gasoline overnight to clean and possibly refresh them to be able to read more accurately . Just a small jar with enough gas in it to submerge the tip and not the wires . You can periodically remove them and tap on your hand to get the cleaning fluid to flow through the opening to get to the area of interest . I was Supprized how much material came out of mine . Look for some corrosion on the connectors like on mine . I'm not a fan of in the gas tank chemicals that get burned up in the cylinders . You can remove the injectors and run some MEK solvent through them but thats more work to get them off . So a in the tank product my be a option .Better spark can be obtained by wrapping the coils with Kapton tape along with the Jaguar TSB preferred Champion RC12YC plugs . You can bring the gap down to the original 0.035 as it was later brought out by Jaguar TSB to 0.040 for longer coil life by reducing the heat generating current . Diamond E3.48 sparkplugs worked for someone else , not bad on price . They produce a cone of spark in theory .The cats can be leached and cleaned with a Oxylic acid solution or you can clean them with citric acid but then again you have to remove them .The Papa Indy 1 and 61 connector that your coils and injectors get there power through get corroded as well as the ground seeking other end at the ECU connector get corroded as well . Clean all your engine wiring grounds including the one aft of the ECU . Clean and wipe possible oil in spark plug wells and wire boots .

Hope this helps , Parker

 

Might be a good idea to check for any exhaust leaks or cracks in the manifold as well. That'll definitely create emissions issues. I used the bg44k product once and was quite happy with that.

 

At a more mundane level, make sure your air filter is clean, and that the car has had a good long run before the test. Also make sure it is hot when delivered for test. The tests are all intended for a hot engine, but the mot doesn't allow time to heat it up on the day. I always try to be there early, having given the car a good run first.
Exhaust leaks before the lambda sensors will kill you so make sure there aren't any!