cat is dead *meow*: test pipe or other options?

so i finally got off my ass and found out my cat actually is dead. literally falling apart. i wanted to buy some header back exhaust system, but dont want to spend alot of money (insert "get what you pay for here"). anyone got any sugesstions? also tried finding test pipes, but that search was in vain also.

its a 1999 Legacy GT wagon 2.5L

 

tl;dr: i need to replace catalytic converter; any exhaust suggestions?

I may or may not have taken a 1.5" extended paddle bit and "cleaned" my cats out with a drill.

DNA MOTORING O2-OXY-SS 90 Degree Angled O2 Check Engine Light Cel Fix Oxygen Spacer Exhaust Extension https://www.amazon.com/dp/B01I3SBJI2/ref=cm_sw_r_cp_apip_iadHlbxp2MzOx

 

DNA Motoring HDS-SI97-25RS Racing Exhaust Header https://www.amazon.com/dp/B01KAA3TQQ/ref=cm_sw_r_cp_apip_Q2hr7TqhONEMV

 

I did not do anything further back yet.

 

 

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Being in CA with all of its emissions regs, your best option is to find someone parting out a car with your exhaust type and switch it. Other than this a replacement cat may be your only other option.

 

O.

car's bout to be registered back in Alabama ;D so i dont have to be emission compliant come this time net week

plus im moving to texas soon

The first O2 sensor in the cat sets your A/F ratio. W/O a cat your fuel trim will be way off and it will not run efficiently.

If the 2nd cat is the issue, it can be gutted.

Not sure of your layout as some have both sensors in the first cat and some have the 2nd sensor in the 2nd cat

 

O.

I gutted both of my cats and I am suffering 23 MPG average mileage. When I had my cats to help set trims i got 25 MPG. But that is just my experience.

The first 02 sensor is before the guts of the cat. How does this cause fuel trims to be off?

 

 

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I've always been told to delete the second cat, not the first one. The second cat merely burns off any particulates not burned by the first one. IMO, it's useless because it serves no other purpose as there isn't any O2 sensors beyond the first one. You definitely need the first cat for fuel economy sake. If it's a daily driver, you'll drop your economy because the first O2 sets the A/F ratio and the second O2 verifies that the first O2 and the cat efficiency is correct.

 

The first 02 sensor is before the guts of the cat. How does this cause fuel trims to be off?

 

The first O2 sensor smells the exhaust to make sure it's not too rich or too lean and adjusts your A/F ratio. That is its sole purpose. By fooling your O2 into thinking the A/F is correct, the ECU cannot account for environmental changes (i.e air temperature, engine load, etc.). This will cause many issues. When your engine needs more air and fuel under heavier loads, the ECU cannot tell the injectors to give it more fuel causing a lean burn situation and can cause internal engine damage. When your engine needs less air and fuel, such as during coasting, it's dumping the same amount of fuel into the engine and causing a rich burn situation and lowers your fuel economy. The second O2 is the checks and balances of the system. It monitors catalytic efficiency to ensure that all of the harmful particulates are being burned efficiently, ensures unburned fuel is not reaching the second cat, and provides the first O2 with a better benchmark on what the proper A/F ratio should be. I have heard reports of using the cheater device on the second O2 with good results, but that is very much dependent on the vehicle.

right now im getting 16 MPG so anything better is fine with me lol but general consensious is replace first and gut second? i dont know how its layed out under my car. i dont have a jack here on post, but ill buy one this weekend and check.

 

but essentially if the first sensor is in front of my first cat, then i should keep the first cat?

i just wish they werent so expensive

right now im getting 16 MPG so anything better is fine with me lol but general consensious is replace first and gut second? i dont know how its layed out under my car. i dont have a jack here on post, but ill buy one this weekend and check.

 

but essentially if the first sensor is in front of my first cat, then i should keep the first cat?

 

Yes, always keep the first cat. It keeps your O2 sensors happy. The first cat isn't expensive if you don't need CA emissions anymore. The part number is WALKER 16089 and is available through RockAuto for around $150

should i go on and change my o2 sensor and spark plugs first? im doing plugs regardless of course

Can't hurt, especially if you're throwing the P0420 code

I'll do that first then. when its P0420 by itself, ts the front sensor that needs replacing right? sorry, im justused to ripping all of this stuff out lol

I got the DNA on my car they sounds great with my borla muffler.

im thinking about getting that while im at it

I'll do that first then. when its P0420 by itself, ts the front sensor that needs replacing right? sorry, im justused to ripping all of this stuff out lol

 

The P0420 usually is the downpipe O2. That is the one that measures the catalyst efficiency and adjusts the fuel trim by reading the amount of O2 that runs by the sensor.

i almost said downstream too lol thanks!

My front cat just blew apart yesterday and it was a magnaflow. I ordered an eastern one from rock auto today after hearing good things about them. I hope it helps with the exhaust smell as well. I just need this car to hold together for a few more years.

hope it works out! i need mine to last a bit longer. it just didt start earlier, but i hit the starter a few times and it started. i guess i gotta add that to the list..

Thanks. What converter did you go with?

Here is what mine looked like today when I removed it.

 

 

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as of right now? none xD im changing the O2 sensor first hoping itll jsut be that. if not then probably walker

There's your problem. There is a nest of tiny tiny bees in your tail pipe.

 

Ouch.

im sure it'll work fine like that! lol