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I need some advice. I used to have a little rich smell from the exaust in the past but it was quite exceptable. Now it has become pretty bad to a point were I'm fuming away other road users (and myself when I have the window open). Even though still pretty, the old blitz is loosing some of her cachet when she smells that bad so something should be done. There are 330.000 km's on the clock so I would think the cats have had their best days. Would replacing the cats help or should I look for other causes first? Everything is stock and well maintained.
 

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I would check the lambda and MAF first, read the plugs and check the coils for visual cracks of any sort.
Problem that you describe is engine working rich, too much petrol and not enough air for the efficient burning during combustion - indicator for bad lambda sensor and/or Mass Air Flow meter.
Catalysator oxydizes CO to CO2 as the latter is less toxic, it does not do anything for unburned fuel - except that a lot of unburned fuel (too rich for long periods) tends to damage the catalysator.

That's what I think.
 
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