MoT emmissions bad fail

1. Claki Established Member Joined: Aug 2009 Horsham Posts: 1855 Leon Cupra 200 TDI

   #1 7th December 2010, 11:14

   Fast idle
   co max 0.300% = 1.06% FAIL
   Hc max200 ppm = 135 pass
   Lambd max 0.970-1.030= 1.010 pass
   Natural idle test
   co max 0.500%= 2.680 % FAIL
   
   Ive tried 2 cats on it now the first failed and the lanbda failed so ive changed them both. but i took the cat off a west coast an got a 0.39% worse reading with it. What could be going on here?
2. swaterman1408 L-plater Joined: Apr 2010 Posts: 49 Saxo vts

   #2 7th December 2010, 11:32

   I had my vts fail yesterday. The same as yours it passed on everything except co.
   The second reading was alot lower than the fist so the cat being very hot sounds like it
   cold be the difference between pass and fail.
3. Matt-T Established Member Joined: Oct 2010 Rednal Posts: 1943 Vauxhall Vectra VW Golf Mk4 Honda Prelude

   #3 7th December 2010, 11:34

   Has the MOT person set the machine up correct, sound silly but if the tempreture of the probe isnt correct the reading may be wrong, also is the car and cat up to tempreture or slightly hot?
4. Claki Established Member Joined: Aug 2009 Horsham Posts: 1855 Leon Cupra 200 TDI

   #4 7th December 2010, 12:18

   No the car was up to temp as it went straight into the bay when i turned up. And i got the same high results with the first cat i tried. Could it be somthing like the 'choke' being stuck on? As my mates 206gti had this and failed emmissions because of it.
5. Railroader Established Member Joined: Dec 2009 Bolton Posts: 1068 Saxo 1.4i sx

   #5 7th December 2010, 13:02

   Does it run ok? Could possibly be a temperature sensor, theres a green and a blue one on the end of the block one of them is for the guage and the other is for the ecu, forget which. The new lambda sensor could be kaput
6. Claki Established Member Joined: Aug 2009 Horsham Posts: 1855 Leon Cupra 200 TDI

   #6 7th December 2010, 14:00

   It does have quite a lumpy idle. and theres a really wiered noise that seems to be coming from the inlet manifold.
7. Claki Established Member Joined: Aug 2009 Horsham Posts: 1855 Leon Cupra 200 TDI

   #7 7th December 2010, 23:42

   Ok, so ive been speaking to alot of people. Some Say it could be a Hairline crack on the inlet mani, Some say it could be Temp sensor/Lanbda sensor. Whos right and whos wrong??
8. Railroader Established Member Joined: Dec 2009 Bolton Posts: 1068 Saxo 1.4i sx

   #8 8th December 2010, 21:04

   WHats this weird noise? Is it a hissing like an air leak? If so theres your prob.
9. Claki Established Member Joined: Aug 2009 Horsham Posts: 1855 Leon Cupra 200 TDI

   #9 9th December 2010, 09:51

   No not like that. it deffo sounds like its causeing problems. im about to get my spare engine home so ill just swap the inlets over.