Lambda sensor and Cat. on corsa | Technical matters | Back Room Forum

Mon 10 Feb 2003 12:31

Lambda sensor and Cat. on corsa - D-8valve

Hi all,

I have a 1400 vauxhall corsa, recently i have noticed a heavy petrol smell in the exhaust fumes, but was assured by a neighbour mechanic that it was probably just the cold weather. The fault indicator on the dash recently came on and off but only through speeds between 50 and 60 mph. It failed its MoT on saturday and I have now worked out that the Lambda sensor is constantly in open loop. This is to be replaced tomorow - my concern relates to the catalytic converter. Is this likely to have been damaged by the excessively rich mixture in the engine? If so is replacement the only option - anyone have any idea of price for something like that?

thanks in advance,
Damien.

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Mon 10 Feb 2003 13:12

Lambda sensor and Cat. on corsa - Pete F

Damien
It's a common misconception that rich mixtures damage cats. In fact rich mixture is used to preserve them under high load conditions. What damages them is misfire due to faulty ignition or possibly weak mixture.
From what you say, it seems likely that the system has detected a faulty sensor and so the light comes on.

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Mon 10 Feb 2003 13:16

Lambda sensor and Cat. on corsa - Cliff Pope

It's a common misconception that rich mixtures damage cats.

But presumably not rich as in flooded? That would be too much of a good thing?

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Mon 10 Feb 2003 13:38

Lambda sensor and Cat. on corsa - Pete F

Cliff
Flooded means that there is liquid fuel in the combustion chamber which contaminates the plug and causes misfire. This would only normally happen at cranking or possibly cold idle conditions. At high loads and speeds, you can put a lot of extra fuel in which simply passes unburned into the exhaust. This cools the cat. You would have to put a ridiculous amount of fuel in under these conditions to cause flooding.

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Mon 10 Feb 2003 16:05

Lambda sensor and Cat. on corsa - D-8valve

Thanks guys,
That has put my mind to rest some what - the only reason I was concerned was I had read that unburnt fuel can sometimes burn in the cat due to the high temp in there and hence cause the damage - but ive not had any experience with this sort of thing before so I thought id ask around rather than go soley with what I read on the net.

Thanks again for your help!
Damien.

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