Mot emissions failure

[Michael.A]

I have now owned my S2 for 1 year,it has a 2.5inch Piper exhaust with pre cat only,it failed emissions at .7co.

The options are.
1.Take car for a serious blast with fuel conditioner and re-test.
2. replace the exhaust with standard unit with cat.
3.find a supplier for a sports cat.

Suggestions Please.

[Jamie N]

I would do 1 and 2 if you can get a standard system somewhere, or maybe even just a cat and pair it with your current set up. I have a spare cat sitting here I use for these sort of problems, could have fitted into your system but it's a hell of a run from Leicstershire to Fife and back just for a cat.

[MPx]

If you like the 2.5 exhaust then why not just buy/fit the sports cat front end ... eg from Scambay

[roy666]

Hooking onto this thread… a similar story. I have an S2 (96 with 150K miles): PNM 2.25 “quiet” (installed 2022) exhaust with the Pre-cat in place. Passed MOTs 22, 23 and 24 (although was v close on Lamda reading in 24). Now fails on Fast idle 1 and 2 on Lambda, needs to be within 0.97-1.03…came out at 1.121 at Fast Idle 1 and 1.149 at Fast Idle 2. It was tested by a reputable (M100 savvy) test centre. Passed on ‘CO’ and ‘HC’. Any ideas welcome: replace Lambda sensor,.. new spark plugs..injectors? Any quick fixes at all? cheers Mike

[roy666]

Just for completeness: new O2 sensor and new spark plugs, big bottle of petrol cleaner in Shell V Power.. and 40 min blast to the test centre, straight onto ramps. Passed with no issues. In chatting to the tester: couldn't really tell whether the new sensor/plugs made all the differnce...but certainly helped.