useless

Hi does the catalytic converter affect fuel economy and idle?With another engine in my car again it idled well today,bt the exhaust sounded heaps quieter.Towards the end of the day the exhaust was louder and it idled a bit rougher.??Are these related?

velociraptor

Im not sure what your your question is please clarify.

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Was extinct but got better

useless

Firstly,I just am trying to find out if a bad catalytic converter affects fuel economy?

Secondly, if it is faulty can it cause rougher idle?

Thanatos

If the Cat is clogged, it definately can affect both fuel economy and idle.

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TIKFD6

TO follow up what Dave has said, if its clogged it will be giving the Oxy sensor false readings, and it will be restricting the flow.

useless

I am getting ridiculous fuel economy,350 kms per tank.Its had 3 engines in it all with the same.Originally it had 420-440 kms.
Everything has been checked and cleaned ,except for the computer and freeflowing exhaust/extractors??My guess is it is flowing too much and making my mixtures lean too......

Baz

I changed mine and it made no difference. At the moment I'm trying a new computer. Ford reckons I should be getting 700 k's to the tank.

Freak

Does the cat rattle at all?

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87' XF FREAK!

useless

Not that I can remember......but I do hear like a rattle when I start it sometimes....not sure if its that.??

Freak

When I did my last cat in, it used to rattle in really low revs. Apparently it's an easy way to tell if your cats stuffed or not and all the inside becomes loose... and rattles.

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87' XF FREAK!