Sanky Posted February 26, 2021 Report Share Posted February 26, 2021 So my car has failed another year on the emissions, despite taking it for a run prior to the MOT. I don’t think it’s just because the car has not been used much, as I know other Porsche owners with 987’s that have little use with no issues. But before I start throwing money at it, anyone on here help diagnose the results and possible cause. I have thought about replacing 2 of 4 the lambda sensors, as they are probably still the original ones. But which ones should I replace first. Pre or Post cat ones? Link to comment Share on other sites More sharing options...
edc Posted February 26, 2021 Report Share Posted February 26, 2021 Are the exhaust and fixings all original? How crusty and leaky are they? Link to comment Share on other sites More sharing options...
Sanky Posted February 26, 2021 Author Report Share Posted February 26, 2021 10 minutes ago, edc said: Are the exhaust and fixings all original? How crusty and leaky are they? Manifolds are original to the replacement engine that was fitted 2 years ago. Left side CAT is new, the triangle joint going from the manifold to the CATS would have been replaced at the same time. Can't feel or hear any leaks around the rest of the U bends and back box, but I will check again. I have only done 1300 miles since the last MOT, if that has anything to do with it. Link to comment Share on other sites More sharing options...
edc Posted February 26, 2021 Report Share Posted February 26, 2021 Definitely check the manifolds and anything pre cat. It's only a high lambda with everything else ok so it suggests cats doing their job and leak isn't at the box. Link to comment Share on other sites More sharing options...
beicmynydd Posted February 26, 2021 Report Share Posted February 26, 2021 Is old petrol likley an issue ? Link to comment Share on other sites More sharing options...
Sanky Posted March 1, 2021 Author Report Share Posted March 1, 2021 So had my service done today, asked them to look at the emission issue at the same time. Seems one of my CATS is leaking and the back box. Has anyone fitted the Dansk exhaust with oval pipe? Or any other recommendations Link to comment Share on other sites More sharing options...
Shazbot Posted March 1, 2021 Report Share Posted March 1, 2021 I had exactly the same on fast idle last MOT. I replaced both cats in the last year at 102K-ish and 16 years. They actually went around the Lambda boss but it was difficult to see or hear due to the second skin design of the end of the original cat, solved the issue. Link to comment Share on other sites More sharing options...
Tipster Posted March 17, 2021 Report Share Posted March 17, 2021 Just picked up on this post, same issue on my mot today, although a much higher Lambda at 1.116, also back box advisory as corroded, I'm thinking new exhaust back box and lambda sensors should sort it, but open to advice? Link to comment Share on other sites More sharing options...
Sanky Posted March 17, 2021 Author Report Share Posted March 17, 2021 2 minutes ago, Tipster said: Just picked up on this post, same issue on my mot today, although a much higher Lambda at 1.116, also back box advisory as corroded, I'm thinking new exhaust back box and lambda sensors should sort it, but open to advice? Just make sure your cats are not leaking, hard to tell as the original ones are double skinned. Link to comment Share on other sites More sharing options...
Tipster Posted March 17, 2021 Report Share Posted March 17, 2021 Thanks, will do.. Link to comment Share on other sites More sharing options...
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