Cats on N/A FC question
#1
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Cats on N/A FC question
Im not huge on FCs yet, but i had a question for you guys
How many cats are there on a N/A FCs, i think theres 2? and is both crucial for passing smog? or just the main one?
Thanks guys
How many cats are there on a N/A FCs, i think theres 2? and is both crucial for passing smog? or just the main one?
Thanks guys
#4
Senior Member
You can always just use a large metal pipe/rod and some elbow-grease on the inside of the pre-cats in order to pass visual inspection, but keep them from failing and free up some airflow
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You should pass without the pre-cats. They shouldn't be doing anything when the main cat is at operating temperature.
The pre-cats get hot, and up to operating temperature very quickly due to their size and position. This reduces emissions created at and after startup. After a short period the main cat will fire off, and start functioning. Somewhere around this point the pre-cats become too hot to function properly, and you are basically running on just the main cat. This is why you will pass smog with the pre-cats gutted.
The pre-cats get hot, and up to operating temperature very quickly due to their size and position. This reduces emissions created at and after startup. After a short period the main cat will fire off, and start functioning. Somewhere around this point the pre-cats become too hot to function properly, and you are basically running on just the main cat. This is why you will pass smog with the pre-cats gutted.
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#9
Bongolio
Wrong the 2 pre cats are after the header and they bolt up to the header. This is of course on an s4.
#11
On an S5 the middle section is essentially a straight pipe (my '89 was this way anyhow). The first section has some sort of mesh stuff in it that acts as a pre-cat. When I replaced the three sections from the manifold back to the y-pipe on my car (I used this Magnaflow combo), I found that the mesh stuff had come loose from the pre-cat and lodged against the front of the brick in the main cat.
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