Gutting Pre-catalytic converter ? - Kia Forum
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#1 (permalink) Old 03-11-2009, 09:04 AM
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Default Gutting Pre-catalytic converter ?

Has anyone gutted their pre-catalytic converter attached to their exhaust manifold with any success as far as how the engine runs and how many codes it will set ?

I have been getting codes that the cat is failing or out of spec and was going to order a new pre-cat and both O2 sensors but wow those things are expensive ! I want to keep the car in good condition and still get good MPG and I figured someone out there had gutted theirs for racing and I was wondering the result of such a mod on mileage ?

The car has been slowly feeling held back and the MPG has gone down some like a clogged cat but don't want to just throw money at it, looking for any cheaper options.

When the car was purchased I was told the cat was failing but not which one, but after being under the car I can see where a hole was drilled after the pre-cat on the manifold then welded back up, which I assume was done to check the pre-cat.

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#2 (permalink) Old 03-12-2009, 07:38 AM
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You don't wanna do that. It will sound like ass, more than likely throw a code. You best bet, would be to either, buy the pre-cat, buy one used on ebay or junk yard, or buy a header set-up. The header will eliminate the pre cat, but you will have to extend one of the o2 sensors. Otherwise your at the cel deal again.
It will really sound like ass if you gut that pre cat.

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#3 (permalink) Old 03-12-2009, 03:53 PM
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1fastkia,

Thanks for your honest reply, that's what I was looking for. I have been looking at Catco or Magnaflow pre-catalytic converters and replacing the O2 sensors with 2 new Delphi sensors.

I currently do not have an OBD2 scanner that reads the "live data stream" but will be getting one as I think I would be money ahead to "diagnose" the problem rather than throwing money at it. What range of voltage readings should I be looking for when monitoring the O2 sensors on a 2001 Kia Sephia 1.8L ?

Any tips on the best catalytic converters or O2 sensors for our Kia's ? My goal is to keep the car stock with slightly improved performance and get the MIL light to go off !

Thanks, Slydog
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#4 (permalink) Old 03-12-2009, 04:07 PM
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Ebay, tons of cats. You could gut your precat as long as your 2nd cat is functioning well. You will have to move the 02 sensor behind the 2nd cat or you will throw a CEL.
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#5 (permalink) Old 03-12-2009, 04:12 PM
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Your precat is part of the exhaust manifold so you will have to get one from a wrecking yard. I have heard of some that have cut the cat of and welded a ney cat onto the manifold but that sounds like a PITA.
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#6 (permalink) Old 03-13-2009, 08:12 AM
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Kiazilla,

Kinda what I was originally thinking on gutting the pre-cat at the manifold as long as the the main cat is good but then it would set codes as the sensor is upstream.

I decided thats way too much work for a car I want to keep stock, so I did find a couple new direct fit pre-cats that bolt right up to the manfold but just wanted to know what brand most guys used as I was looking at Catco and Magnalow pre-cats that are direct fit for our cars.

From my research the Magnaflow will typically flow a little better but I was concerned of setting MIL codes as it seems these Kia's are touchy with any mods or non-original parts being used.

I just coded the car out again after clearing the codes a month ago and it had P0422 (cat) and P0128 (temp low) so I cleared the codes and will drive another week while I wait on my new OBD2 scanner with "live data stream" so I can monitor the O2 sensors and the engine temp via the scanner.

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#7 (permalink) Old 07-18-2012, 05:49 PM
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I need to make sure we're talking about the same object. I need an item as illustrated here:

2003 kia spectra: converters..pipe..Repair shop is tell me..manifold - JustAnswer

What I see on ebay is not the item I need (a precat) but what appears to be 90 degree angle pipe that is bolted (removable) between the intake manifold (precat ?) and catalytic converter and has the sensor attached to it. It was damaged by a pot hole and is making a lot of noise.
What do you call this thing ?

Last edited by matmcgill; 07-18-2012 at 06:02 PM.
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#8 (permalink) Old 07-19-2012, 05:14 PM
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Typically, it's called a front pipe.

Laptop/USB OBD-II Scanner at Amazon: search "ScanTool 423001 ElmScan 5" at amazon.com
OBD-II Codes: http://www.obd-codes.com/trouble_codes/
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#9 (permalink) Old 07-19-2012, 05:17 PM
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Or may be listed as a "Header Pipe - Front" ..

Kia Front Pipe - Kia Front Pipes | Auto Parts Warehouse | Free Shipping

Laptop/USB OBD-II Scanner at Amazon: search "ScanTool 423001 ElmScan 5" at amazon.com
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#10 (permalink) Old 07-19-2012, 06:23 PM
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Thanks,
Front Flex Exhaust Pipe.
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