[Jet1990]

Hi all,

I've recently bought a 330i and theres a fault code saying the nitric oxide catalytic converter is ageing ( plus the car has quite a bit of white smoke even when up to temperature) so im contemplating de catting the exhaust but ive read that this engine has upto 4 cats on it? is this true? and if i was to de cat the car would this make the nox sensor throw out a load of funny data thus messing around with the air/ fuel ratio as the car is currently only giving me 18mpg ( i got 130 miles to half a tank of urban driving)

anyone else here experienced that issue?

thanks

[RajB]

The 335i has 4 cats so it well maybe true of the 330i too. I've binned all my cats on mine and apart from the errors for not have them there, there is no detrimental effect on the engine.

Not sure the white smoke is due to the cat's though as could be more head gasket or something.

[Jet1990]

Ive had a good look in the oil filler and no signs of gunk etc or any other symptoms of it. by decatting the car did you have to bypass the nox sensor?

[BMB063]

You'll definitely get a code in the dash if you decat and don't have a jb4 or something.

[Jet1990]

Originally Posted by BMB063

You'll definitely get a code in the dash if you decat and don't have a jb4 or something.

JB4?

[Tr1ppy]

how do people get round MOTs when de-catting?

[BMB063]

Originally Posted by Jet1990

JB4?

http://www.burgertuning.com/jb4_pnp_...nce_tuner.html

Originally Posted by Tr1ppy

how do people get round MOTs when de-catting?

Well in the US, only certain states require emission tests and some (like Ohio) only have requirements in certain counties. Like Cleveland requires an E check, but Columbus doesn't. I lived in Florida and the entire state doesn't require it.

If you live in a state that requires it, I guess you either swap it out when you go for the check, or there are other ways around it I suppose. I've just been lucky to avoid those areas with the checks.

[RajB]

Originally Posted by Jet1990

Ive had a good look in the oil filler and no signs of gunk etc or any other symptoms of it. by decatting the car did you have to bypass the nox sensor?

Fair dos then. You'll get lamda sensor errors but you can have them coded out with a remap to take account of the extra flow.

Originally Posted by Tr1ppy

how do people get round MOTs when de-catting?

You need a 'friendly' MOT centre lol

[Jet1990]

Originally Posted by RajB

Fair dos then. You'll get lamda sensor errors but you can have them coded out with a remap to take account of the extra flow.



You need a 'friendly' MOT centre lol

My thoughts exactly Raj! i plan to decat the car as theres a fault code saying cat ageing. i checked with bmw and its had the coil pack and all 6 injectors replaced as well as the nox sensor but im thinking of sorting out this nox sensor at the same time i get a remap done to battle the o2 and nox sensor. cheaper than replacing both cat and nox sensor in my eyes. have you heard of anyone doing this before?