Quick question on air filters/induction kits and emissions

1. user_18250 Established Member Joined: Sep 2007 Swadlincote Posts: 1185 2003 Black VTR

   #1 13th February 2012, 21:45

   Car just failed its MOT test on emissions, HC was fine and CO failed by 0.09% so im assuming its because of the non type approved CAT i fitted.
   
   Got a proper type approved one on the way, but just out of interest...
   
   What would give better emissions my standard airbox or the raceland with a twin green cone inside I have fitted currently?
   
   Im assuming the standard air box but thought Id check whether it made a difference first.
2. user_20080 Saxperience Hardcore! Joined: Dec 2007 smurfland. Posts: 17346 Ex saxo owner.

   #2 13th February 2012, 21:53

   Interesting one,the only thing I can think of is that the filter you`re using maybe dirty/clogged up.So the engine is working harder,i`ve run an open foam pipercross and am now using the standard airbox with a standard filter,both set-ups passed the test.
3. LVC Frequent Poster Joined: Aug 2010 Le Mans, France Posts: 976 VTS, Hawkeye WRX, Def90 & Freelander HSE (ex-VTR)

   #3 13th February 2012, 21:58

   Yep a clean filter of any type should not really effect the emissions but a naff CAT or clogged air filter will certainly cause problems.
4. user_18250 Established Member Joined: Sep 2007 Swadlincote Posts: 1185 2003 Black VTR

   #4 13th February 2012, 21:58

   Quote:

   Originally Posted by stevo67 Interesting one,the only thing I can think of is that the filter you`re using maybe dirty/clogged up.So the engine is working harder,i`ve run an open foam pipercross and am now using the standard airbox with a standard filter,both set-ups passed the test.

   Im thinking the CAT is the problem as it was a very cheap one I bought about £40 new.
   
   The filter in the box isnt too dirty but its not fresh either.
   
   Just wondered which setup would be best, id assume less airflow with the standard box would mean the ECU would also fuel less to even the mix out.
   
   Not that it would be a noticeable change, just I have a box in my shed and will do every little helps if it gets it through the MOT.
   
   Problem im having is I fitted a 4-1 and mk1 oil filter to a mk2 so im now having to experiment with underfloor cats for mots lol
5. LVC Frequent Poster Joined: Aug 2010 Le Mans, France Posts: 976 VTS, Hawkeye WRX, Def90 & Freelander HSE (ex-VTR)

   #5 13th February 2012, 22:03

   Cheap CATs are a disaster and waste of money - if you're lucky they'll last for one MOT. Had a nightmare with cheap CATs on my VTS - ended up buying a Walker one for £100 reduced from the 600€ they wanted in the local "kwik fit" equivalent.