Technical Failing MOT on monoxide emissions...

[fubar]

Hi all,
Had the Coupe 16v N/A in the garage lately and it keeps failing on the emissions. Particulates are fine (I blew the soot out with plenty of 99-Octane and a bottle of RedEx, lol). When it comes to CO though I fail in the mid-RPM range... idle seems okay as does higher RPM, very strange.

I've put in a new braided flex pipe/exhaust mid-section, new catalytic converter & gaskets, new air filter, new battery, new relays on the fusebox - to no avail.

Before these repairs I was getting bits of honey-comb stuff coming out of the exhaust which I was told was the old catalytic converter crumbling, I also got the horse-hair crap coming out of the back box.

Any ideas? Could there be a blockage or is this an issue with the oxygen sensor?

 

[ChrisUK]

Particulates is usually the cat breaking like you say. But you've replaced it...

Have you reset the ECU? by leaving neg battery terminal disconnected for a couple hours which will force it to re-learn everything.

Also was it a genuine cat or a crappy generic one (they are renowned to fail).

 

[fubar]

I'll give the ECU thing a try, see what happens. It's a bit scary though as last time my battery failed I couldn't stop the alarm going off. I had to leave the battery off overnight then press the fob 15 times whilst standing on the hood release catch or something crazy like that!

What I have noticed when I've finished journey is that if I have locked the doors from the button inside - when I get out and activate the alarm I have to press once (beep), twice (deactivate) then thrice (activate alarm). It won't just lock on the first press.

Other odd things have happened such as cutting out at bends/mid RPM (3rd gear) and car alarm deactivating on it's own when left overnight (although the former hasn't happened since new battery).

My new catalytic converter is a £150 3rd party thing, a local Fiat dealer wanted £400 for an official part (so I just got the official gasket & back ring for £15). I only paid £800 for the car!

Could my old battery have confused the ECU? Reading another recent thread it could be the crank sensor going - if I put my foot down in 3rd gear I sometimes have to wait for the engine (sounds like it's catching up).

Who knows.

 

[ChrisUK]

Disarm the alarm first before disconnecting battery and it should be ok