Annoying MOT emissions failure

1. ashleyoneill Frequent Poster Joined: Oct 2005 Chippenham, Wiltshire Posts: 796 Mk2 Wicked Red VTS

   #1 20th December 2010, 19:05

   I have an annoying mot emissions failure problem. It's a single plug 99 VTS
   
   All my readings are fine apart from CO at idle and fast idle is 0.6% instead of the required 0.3%
   
   The following has been done so far
   
   - standard induction put back on
   - standard exhaust put back on
   - known working CAT on the car
   - spare map sensor used
   - diagnostics show no sensor faults
   
   Since the last MOT which it passed the following has changed
   
   - manifold swapped for another one as gearbox bracket snapped
   
   It's now been to 3 garages and they won't touch it. It's going to a 4th that's a specialist at emissions failures. Under the bonet it sounds like there is an exhaust blow but can't work out if it's noisy injectors or a blow.
   
   Any ideas anyone? It's done 115,000
2. user_31412 Established Member Joined: Feb 2009 ★ West / North Yorkshire ★ Posts: 1653

   #2 20th December 2010, 19:16

   High CO will be caused by a rich fuel mixture. Usual suspects are the lambda sensor or ECU coolant temperature sensor.
3. ashleyoneill Frequent Poster Joined: Oct 2005 Chippenham, Wiltshire Posts: 796 Mk2 Wicked Red VTS

   #3 20th December 2010, 19:29

   I did think that it gut be the Temp sensor (green plug one is for ecu right) and that it might not be going into closed loop but that sensor was changed last year when I had an idle problem and seems to be working ok.
   
   I have a spare lambda that could be used to check but after that who knows.
   
   The lamdba reading on the mot was okay but I guess that doesn't mean the sensor isn't faulty??
   
   I think it might cost less to buy and fit another engine. I can do that in around 10/12 hours but it's a lot of hassle.
4. user_15516 Saxperience Post Whore Joined: Apr 2007 Posts: 6640 Integra DC5R & VTS

   #4 20th December 2010, 19:35

   As outrage has said, sounds like it's running rich.
   
   If you're sure the CAT is ok, then it can only really be the lambda causing the problem. Make sure the CAT is hot before the emissions test too.
5. user_31412 Established Member Joined: Feb 2009 ★ West / North Yorkshire ★ Posts: 1653

   #5 20th December 2010, 19:45

   Probably worth a shot before swapping engines - seems a lot of work :
   
   C2 C3 C4 C5 C8 SAXO XSARA COOLANT TEMPERATURE SWITCH
   
   Then a decent NTK lambda : NGK NTK LAMBDA SENSOR OZA448-E58 (you'll need to solder the old connector on but if you can do an engine swap im sure thats not an issue )
   
   It's only .3% out so it will only be something simple.. Try running it on V-Power if its on supermarket shit at the moment?
6. ashleyoneill Frequent Poster Joined: Oct 2005 Chippenham, Wiltshire Posts: 796 Mk2 Wicked Red VTS

   #6 20th December 2010, 20:02

   Will try lambda and look at running it on some better fuel. Can't get it anywhere though as it's got no MOT
7. Railroader Established Member Joined: Dec 2009 Bolton Posts: 1068 Saxo 1.4i sx

   #7 20th December 2010, 20:18

   Its probably blowing at the exhaust manifold if you have swapped it. that in itself will mess up emissions
8. ashleyoneill Frequent Poster Joined: Oct 2005 Chippenham, Wiltshire Posts: 796 Mk2 Wicked Red VTS

   #8 23rd December 2010, 11:58

   Okay, so its now passed its MOT after taking it to a top diagnostics guy that said all the sensors are in top condition and it was 100% the CAT.
   
   My friends one i tried is obviously dead as with my new CAT it managed the following. CO was at 0.6% before.
   
   Fast Idle test
   
   CO 0.097 %
   HC 64 ppm
   Lamda 1.016