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Old 07-10-2013, 10:22 AM   #3 (permalink)
California98Civic
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Join Date: Mar 2011
Location: Coastal Southern California
Posts: 6,299

Black and Green - '98 Honda Civic DX Coupe
Team Honda
90 day: 66.42 mpg (US)

Black and Red - '00 Nashbar Custom built eBike
90 day: 3671.43 mpg (US)
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Quote:
Originally Posted by cbaber View Post
Is this for your car or just in general?

CAT's exist to filter the exhaust gases. They don't really enhance performance in terms of power or fuel economy. In fact, once they become clogged and dirty they can actually hinder your fuel economy. The important thing is to have a clean and non-leaking CAT.

What the seller is referring to when they mention double the Rhodium is how this CAT can somehow hide your engines poor health. OBDII cars 1996 and newer usually have 2 oxygen sensors. One in front, and one behind the CAT. The goal of the 2nd sensor is to monitor the performance of the CAT, making sure it is filtering out the exhaust gases sufficiently. This seller implies that by purchasing this CAT it can cure your engines poor health that has been setting the check engine lights off.

But, any new CAT will probably be sufficient. When you get a CEL for a faulty CAT it is usually because it is clogged or has broken up inside and developed a leak that doesn't allow proper filtration. I don't believe you should pick a CAT because the seller claims it has more Rhodium.

$212 is a bit steep. Go search for Magnaflow Hi Flow CAT's on Google. You can find replacement, hi performance CAT's for about $70. I have used them twice on 2 different cars and have not had a problem. I even use one on my civic HX, which is suppose to produce even more harmful gases during lean-burn. The CAT has never triggered a CEL so I would say it can handle any high-mileage or lean-burn engine.

If you need advice on a replacement CAT for your specific car let me know. I use to have the same exhaust manifold design as you which has the built in CAT. Unless you buy a direct replacement which is expensive you have to convert your exhaust system to the 96-00 Civic EX with the standard exhaust manifold and downtube setup. I did this to my car and was able to purchase a used exhaust manifold, downtube, and brand new Magnaflow CAT for less than half the price of the replacement.
Thanks for this. Unfortunately I don't think I can swap the emissions equipment in California without the approval of the CARB authority that regulates that out here. In my last emissions test, my emissions were high but still within the required ranges ranges. The tech noted unburnt fuel in the CAT and suspected the O2 sensor. Shortly after the test I got an upstream O2 CEL. I replaced both. Do you think the unburnt fuel situation could "cure itself"? I have seen guys online "cleaning" CATs. I am not inclined to try that without clear evidence of effectiveness.
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See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.



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