Got B/B and de-cat centre on MY99. Went to get an MOT and the car failed on emmissions despite still having the front cat and getting it real hot. The reading was way out.
As this happened i decided to put the standard peeshooter and centre section back on.
Went back for MOT First time the reading was way out, but the fan was on. second attempt it was OK, fans were not on.
Could the car have a problem? From what i've heard the car should still pass emmisions with standard downpipe.

 

It should fly through with just the downpipe.

 

Agreed

Should pass with just the downpipe. Mine had 0% CO last time it was MOT'd with the standard downpipe and centre decat. I believe it'll pass with a decat downpipe and with the centre (2nd) cat fitted too.

Not anymore now - as its fully decatted

Either the downpipe cat is knackered (doubtful - as it would have shattered and blocked your exhaust up - Had that happen on my old XR3i). Or you have a sensor fault somewhere, most likely suspects are the Oxygen sensor, MAF, and coolant sensors. Also should add a Vacuum leak or duff gaskets or even head gaskets can cause dodgy emissions too.

Not to forget spark plugs (change them every 3 years) thay can play up - yet look perfectly fine

Failing that a dodgy or clogged injector or a load of carbon deposits on the inlet and combustion chambers, In which a fuel system clean and decoke is called for (can also help dodgy OS sensors too - alledgedly).


BTW 2nd cat is mainly there to finish the 1st cats job and get rid of any residual nasties. Being further away from the engine means it'll take longer to "light." Thus why it failed 1st time during your 2nd MOT.

[Edited by ALi-B - 5/3/2003 12:57:41 PM]

 

Cheers for help Ali.