John-M 0 Posted October 19, 2007 OK, well, three questions ! 1. What might cause high CO readings on the MOT emissions report sheet ? Assume engine / oil temperatures is OK 2. What would be the effect, in terms of emissions readings, of a CAT beginning to fail ? 3. Is there anywhere on the net that gives an underatandable explanation of the various emissions test results ? If anyone can help I'd be grateful Quote Share this post Link to post Share on other sites
corozin 0 Posted October 19, 2007 OK, well, three questions ! 1. What might cause high CO readings on the MOT emissions report sheet ? Assume engine / oil temperatures is OK 2. What would be the effect, in terms of emissions readings, of a CAT beginning to fail ? 3. Is there anywhere on the net that gives an underatandable explanation of the various emissions test results ? If anyone can help I'd be grateful Well... 1) It could be quite a number of things. Faulty plugs, or injectors, could be a failed catalytic convertor, or possibly even something like piston rings starting to fail. If the engine "smokes" at all once warmed up it will almost certainly fail on HC emission, but if it's not that and the car feels like it's running ok in every other respect then I'd take a punt and guess it's the cat. 2) If you have a knackered cat, you HC emissions will be high, possibly enough to fail the MOT. To be honest a good running VR6 is actually marginal emissions anyway - some people have de-catted and get good enough readings to pass the MOT. 3) Not that I'm aware of. If you have a VR6 I believe it needs to be under 225 "carbons" but to be honest understanding the techies won't really help you fix the problem. Start by looking for oil deposits in the exhaust, or oily smoke on the overrun. If that's ok then move on. 4) Probably of more help is this : VAG will charge you £480+VAT for a replacement cat, but I recently had a sports cat replacement supplied & fitted by Mike Stokes Motorsport in Bournemouth for just £237 incl VAT. At that price it might be worth a trip down the M3. HTH John (M - the original John M) Quote Share this post Link to post Share on other sites
John-M 0 Posted October 24, 2007 Thanks for that - emissions knowledge seems to be a bit of a black art :) Anyone else any thoughts ?? btw, you claim to be the original John M - are we talking about in life or 'in here' ?? Grins Quote Share this post Link to post Share on other sites
