More emission problems

[cam]

Put in cat cleaner new plugs and an oil change, caned it for 250 miles took it into the shop hot and it still failed on emissions.
Mechanic said it is missing and unburnt fuel in the exhaust is causing the failure, he said it is probably a sensor not working, anyone got an idea where to start looking as I can't find anyone close to me who can help.

Cam

[Neptune]

have you tried replacing the sensors? is your cat in good nick? what reading was out... the lambda? CO? are you failing on idle or fast idle etc?

what car are we talking... N/A? Turbo? Year?

[cam]

Thanks for the reply

It is a 95 UK N/A

It had a new cat and lambda this time last year

It is OK on normal idle but is failing on fast idle CO 0.6% Lambda 1.2%

Cam

[Neptune]

hmm they should still be fine then, my old N/A i had to go for a short 5 mile blast, reverse into the test station and do the test right away for it to pass... i know they can be awkward.

unfortunately my knowledge on emissions is not that great... so hopefully someone else can post..

So cat and lambda are done! What about service items, sparks, dizzy etc?

how healthy is the engine? might be worth doing a compression test, or even taking it to a rolling road to get a diagnosis on the engine /mixture.