Bypassing Catalytic Converters, and Sensor?

S

SpilledSalt

Member
:
03 Mazda Protege
Hey Mazda247,
Im a new owner of a 2003 Mazda Protege. My check engine light came on after putting on 300 miles on the car. -_-
I am already certain its throwing me a o2 sensor fault. Here in the state of Minnesota I have no emissions so I would like to let this baby "breath." I have searched ebay and others for a nice cheap headers back system, but couldn't find much.
does anyone know a alternative route? Pounding out the honey comb perhaps? Ticks with the o2 sensors?
where is the "pre-cat" located, Right after the headers? Witch sensor is more vital, the first or second?
sorry is this seems likes a ramble. Basically I want performance, help the engine run smoother, and get rid of that damn Check engine light that's starring me in the face!!!

Any reference links for parts is appreciated

car info:
03 Mazda Protege
130,000 miles
5-speed
 
I had a similar issue with my 'ES. I replaced the exhaust manifold and primary cat with an OBX header from ebay and took the midpipe out and used a long pry bar with a hammer and much patience to gut out the secondary cat. by doing that you will get a CEL. so I bought 2 spark plug non foulers and used them. my CEL only comes on once every 6 months or so. the primary o2 sensor will not be affected since it's reading your o2 coming out of the cylinders before the cat. so the non fouler only needs to be installed on the secondary cat. then definitely junk that old stock muffler and go with CS or something similar.
 
Thanks for your reply,
Just got back from oreilly's and yup its the p0421 code.
I looked on eBay for some headers the obx ones are about 200. Are there any review or opions on the 80-100 dollar ones? I picked up some of the foulers. Should I install them on the 1st o2 sensor for now. I looked at the second one. Looks the the prior owner alrdy put some foulers on the second o2.
Again thanks for you reply
 
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Nonfouler on secondary would fix p0421 its what I did last weekend.I dont think doing it to the first would anything because its before the cat.maybe the nonfoulers are lose or you have a exhaust leak
 
^^^ non foulers on the primary o2 would do you no good since the purpose of using the non foulers Is to keep the SECONDARY o2 sensor out of the direct flow of rich exhaust gasses. you're in a since modifying the signal that the o2 reads and sends to the ecu. with the o2 out of the direct flow of rich gasses will make the sensor believe the cars cat is working fine and does not trip a CEL.

as for the OBX headers, I thought it was the bees knees when I opened the package. looked awesome until I installed it and the flange where the header mates to the midpipe was at too much of an upwards angle and caused an exhaust leak. sounded like s***. I cut the flanges off both pipes and welded a flex pipe in place of them to maintain flex since it deleted the spring bolts.
 
I'll try and add a second fouler to bottom o2 tonight. There's only one on there now. By ticking the sensor and making the richness run where it thinks it should, in the long run would that cause build up in the cat? All in all cats need to go.
 
If you are going to do the non fouler trick go to the how-to section and look at the thread.you drill one out and have to use collapsible washers
 
I'm hesitant on installing the headers.... those bolts on that down pipe are a mess. Duren03msp I see your from bunsville. I live in Brooklyn park!
 
ya I am. and those bolts are usually a mess. I would recommend getting replacements bolts, nuts, and springs. they usually come in a kit.
 
or if you don't want to purchace a header and deal with fitment issues I have a almost brand new primary cat off my '02. I could sell to ya.
 
SpilledSalt said:
Thanks for your reply,
Just got back from oreilly's and yup its the p0421 code.
I looked on eBay for some headers the obx ones are about 200. Are there any review or opions on the 80-100 dollar ones? I picked up some of the foulers. Should I install them on the 1st o2 sensor for now. I looked at the second one. Looks the the prior owner alrdy put some foulers on the second o2.
Again thanks for you reply
Click to expand...

You might as well save the hassle and buy a walker cat. the 80-100 dollar cats you see are "universal" and usually only good for the secondary cat. your pre-cat is what usually fails on these cars, and you'll want to pay the 200-300 dollar range to fix it.

If there is a spark plug defouler already on the downstream 02, remove it. it's adjusting the 02 sensor readings, and probably causing it to have a "lean" code.

Having a header on a car is perfectly normal, but it is illegal to gut your catalytic converter. since you still have to do your emissions testing, i'd just put it all back to factory and call it a day. it sucks you have to spend 200 to 300 dollars like that after you just got the car, but remember... the new cat will have a lifetime warranty on it. Just make sure to keep all of your ignition parts in good working condition... i.e. your plugs, two coil packs, and two wires. producing a misfire in your car increases the chance of fouling your cat.

EDIT: I just re-read your post, you're talking about 80-100 dollar headers.

Basically, an 80-100 dollar header is the same scenario "you get what you pay for". Fleabay can have some neat stuff, but some of the chinese manufacturers produce these parts and dont last very long.


I paid 44 bucks for a knockoff flowmaster muffler for my jeep once, it rusted out within 2 years.
 
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03protolx said:
You might as well save the hassle and buy a walker cat. the 80-100 dollar cats you see are "universal" and usually only good for the secondary cat. your pre-cat is what usually fails on these cars, and you'll want to pay the 200-300 dollar range to fix it.

If there is a spark plug defouler already on the downstream 02, remove it. it's adjusting the 02 sensor readings, and probably causing it to have a "lean" code.

Having a header on a car is perfectly normal, but it is illegal to gut your catalytic converter. since you still have to do your emissions testing, i'd just put it all back to factory and call it a day. it sucks you have to spend 200 to 300 dollars like that after you just got the car, but remember... the new cat will have a lifetime warranty on it. Just make sure to keep all of your ignition parts in good working condition... i.e. your plugs, two coil packs, and two wires. producing a misfire in your car increases the chance of fouling your cat.

EDIT: I just re-read your post, you're talking about 80-100 dollar headers.

Basically, an 80-100 dollar header is the same scenario "you get what you pay for". Fleabay can have some neat stuff, but some of the chinese manufacturers produce these parts and dont last very long.


I paid 44 bucks for a knockoff flowmaster muffler for my jeep once, it rusted out within 2 years.
Click to expand...

FYI, MN has no emissions testing.
 
ah, gotcha. Still federal law to have a working pre-cat, but as you do...go ahead and swap it for a header.
 
I have a 2001 protg it has been running fine up until a month ago when the radio stopped working for no reason. Now it's cutting off when I am at stop lights. Any ideas why? Been to a mechanic and he was no help.
 
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