Hi All,
I have read numerous posts on this subject, and am going to test the lambda sensor this afternoon.
The question I am asking is that the emission readings have changed so drastically that I think I may have missed something whilst refurbing the NA over the last few months. Perhaps someone more knowledgeable can point me in the right direction.
The MOT test was carried out in France.
I have had the car tested twice in the last year and only driven 234 miles between tests due to the renovation work.
As part of the renovation I have changed the oil, air filter, fuel filter and plugs. The timing belt was also changed. The car runs sweetly.
I have removed the engine and box during the work. I have also sprayed the downpipe which houses the lambda sensor, although the sensor was removed during this process. It was stored safely, but perhaps was damaged during removal? Are they that fragile? I have ensured that the O2 sensor is connected
The readings from the last test were
O2 Idle 0.32% ( < 0.5% )
O2 fast idle 0.3% ( < or = 0.3% )
Lambda 1.030 ( 0.97 to 1.03 )
234 miles later
O2 idle 4.22%
O2 fast idle 4.56%
Lambda 0.88
The MOT technicien indicated he thought it may be the lambda sensor. I asked why as that was the only reding which had not only passed, but improved. He stated that if the O2 readings changed, so would the lambda reading. In his experience the lambda was the issue, not the cat.
This is an area out of my field of experience, so any and all help greatly appreciated.