With nothing better todo I thought that changing theOxygen sensor on the MX5 in the downpipe may be in order of the day.
This is the blighter. In some cases also known as the Lambda sensor. It keeps and eye on the exhust emmissions. Now when it wen through the MOT last week it apparently was just within the opperating limit. So either this or the Cat is playing up at 12 years of abuse. And as there is loads of soot on the exhausts, which means its overfueling, I guess this sensor is either not working or reacting slowly. Anyway the MX5 uses a common one that is easy to obtain. You can either buy the Mazda one at £186 or the lucas one for £40, so me being tight I bought the Lucas one.
While you could see the sensor from above, you could see it even better with the wheel off and looking at it through the wheel arch. The thing is to get it off you need a very long 22mm spaner and you cannot get one in thats long enough to get it undone.
I used the old trick of warming the down pipe and in the end it came down to brute force and a mallet.
Well with the old one out I was dissapointed to see the sensor itself was not covered in soot. Mind this doesn't mean its functioning properly but would have been a sign that it was definetly dead.
Of course not being a Mazda lambda ment I had to connect the wires to the exisiting plug.
A few mintues latter and the new one is in place.
The wires rerouted to the plug on the top of the coil pack and she's ready to go once more.