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[x25xe]

Thanks for all the replies.

Lambda does measure the amount of oxygen in the exhaust gas.  I am still not sure how the mot test equipment knows how the lambda sensor is switching though.  I guess that it measures oxygen levels over a set period and works out the lambda switching from that?  As there are 2 sensors on the V6 I would guess that they are both not switching in the second fast idle test.

I tend not to drive hard so the system could well do with a good blasting I guess.  Air filter was changed about 5 months ago and during that time I have covered 3 thousand miles.  Looking forward to saving the £600, but it will take me more than a Saturday morning to do it all!

I feel that some of my questions are of a technical nature and therefore this ought to be moved to the General help section.  Could one of the admins do this for me please?  I apologise for this thread becoming more technical.  I started it just making general conversation - sorry

[Kevin Wood]

I am still not sure how the mot test equipment knows how the lambda sensor is switching though.

I think it deduces the Lambda value from the balance of gases in the exhaust to check that the sensors are doing their job. It's a bit odd that you've got a value of zero in one of the fast idle tests. Almost looks like the emissions tester gave up trying to calculate it.

If the Lambda sensors aren't switching you'd get a fault light from the ECU so my guess is that they're working but being disturbed by an air leak. The emissions are pretty clean on the natural idle test (below the speed at which the Lambda sensors are active) so I'd Hazard a guess that the cats are OK.

You can sometimes clean Lambda sensors by removing them from the exhaust and heating the tips in a blowtorch flame but giving it a good spanking would probably achieve the same.

A fill up with good quality petrol might help too. It didn't get upset by the recent contaminated fuel issue I suppose?

Kevin

[x25xe]

Hi Kevin,

I think that I managed to avoid the petrol issue - the last time I filled up in the Omega was the Brackley cam belt party.  This thought did cross my mind though.  I generally use Shell fuel and never go to Sainsbury's etc for petrol.

There has been no fault light showing which I partly why I could not understand why the zero reading.

So, it looks like it is the leaks that are upsetting it then and, hopefully, nothing else to worry about.

Thanks for your input

[Kevin Wood]

It was on the way home from Brackley that mine expressed its' dislike for Morrisons' fuel. Edwardmickey got a bad load of fuel from Tesco in Brackley at the same time.

Kevin

[x25xe]

Oh dear,

Maybe I did not escape then.  However, it was Shell fuel used - I thought that only supermarkets were affected.

I will get the new exhaust on and worry about the emissions side of things after that I reckon.