Subaru Impreza GC8 & RS Forum & Community banner
1 - 20 of 23 Posts

·
Registered
2005 Baja Turbo
Joined
·
1,448 Posts
Discussion Starter · #1 ·
I've got a 1998 LGT with the 2.5 DOHC motor.

My primary cat has failed. Or the second O2 sensor, either way, both are getting replaced.

So, should I replace the secondary cat as well?

Pros: Using high flow cats, I'll get better performance
Going to put both cats before the O2 sensor so I have less chances of getting a P0420
Not risking the possibility that the second cat is plugged

Cons: More expensive
???

Opinions? Remember, I gotta make sure this car passes emissions, so no going catless. :( Plus, no local shops are willing to do that anyway.
 

·
WTF WAS THAT?!?
'05 Legacy GT, '09 Forester X
Joined
·
4,433 Posts
do them both.
get two universal high flows and have a good muffler shop make you a cat pipe.
keep the sensors in the stock location for ease of installation.
 

·
JBCUSTOMS
2001 Impreza 2.5RS STM
Joined
·
2,486 Posts
remove both cats to get better exhaust flow... add a mil eliminator to prevent CELs.
 

·
Registered
2002 Impreza RS EJ251
Joined
·
269 Posts
I installed one HFC on my 02RS and installed a couple of spacers on the rear 02 sensor> I have not had a CEL for a year
 

·
Registered
07 WRX, 06 STI, 00 RS, 05 LGT
Joined
·
69 Posts
I can't if I want to pass emissions.
Yea you can, most dont visually inspect if you have a cat. They are lazy and just walk around your car with the mirror. As long as you have no cel or code stored in the ecu your good. I've had a full tbe since I owned my sti and never had any issues with emissions.

On a side note can anyone help me with my issue? I currently have the p0420 code on my 00' rs. I replaced both sensors as well as a defouler and the light came back on within 40 miles of driving. I do hear a tiny rattle at times when I begin to accelerate so im guessing its the cat.

So basically my question is what are the best/cheapest options? Just get a brand new oem cat and have it replaced, install something to trick the ecu if possible, find an aftermarket(what are good ones?) cat and have a shop cut out my old one and weld in the new one? Thanks for any input.
 

·
Registered
98 impreza outback
Joined
·
70 Posts
I bought a tsudo test pipe 2.25in with high flow cat and it comes with a adapter you put on the rear o2 sensor and it never comes on i paid 200 but you can pick them up for cheaper now
 

·
Registered
07 WRX, 06 STI, 00 RS, 05 LGT
Joined
·
69 Posts
I bought a tsudo test pipe 2.25in with high flow cat and it comes with a adapter you put on the rear o2 sensor and it never comes on i paid 200 but you can pick them up for cheaper now
Thanks I will certainly look into that. I have to be honest im not to familiar with na cars. If I get a test pipe will it just bolt on or do I need to have something cut and welded? I see the test pipe had flanges on both end so I assume it can just bolt up.

EDIT: just answered my own question but did notice one thing on the websites where you can purchase the test pipe. They all have this somewhere," Note: This test pipe removes stock OEM catalytic converter, which might trigger a CEL (check engine light)." Do they just put this for legal reasons?
 

·
Registered
07 WRX, 06 STI, 00 RS, 05 LGT
Joined
·
69 Posts
Dude..... FAIL ON A POST FROM 2008!
It actually wasn't a fail. Im from the nasioc world were people hate(incl. myself) when someone starts a new thread on a topic that has been talked about several times. I was searching through old threads looking for some answers to my problem and didn't find exactly what I was looking for so I figured why not just post in an old thread instead of making a new one.
 

·
Registered
98 impreza outback
Joined
·
70 Posts
It was a straight bolt on i actually had to cut and extend my cat back 3in only because its ebay and they dont fit exact lol other than that it was easy and they also make ones without high flow cats which are cheaper but are a bit louder sound too.
 

·
Registered
2000 2.5RS/C BRP
Joined
·
2,321 Posts
Yeah, I run that on my RS/C. It's a direct bolt up, includes the 90* MIL fix and it has a plug for the third O2 bung (I used it for an LC-1). One caveat is that it's a 3" pipe, so the gaskets have a very small sealing area and like to leak if they aren't lined up perfectly.

Also on mine I had to grind the middle transmission hanger down, it was knocking on my subframe.
 

·
Registered
98 impreza outback
Joined
·
70 Posts
Yeah same here i cut mine but it still hits a little might have to grind down where its hitting
 

·
Registered
07 WRX, 06 STI, 00 RS, 05 LGT
Joined
·
69 Posts
Thanks for the info guys. I'll probably go that route. Thanks for the link dakine, unfortunately i've checked with them and a few other vendors and they are all on back order 4-10 weeks. I found one company on ebay claiming to have in stock but they only sell it with the package deal incl uel headers as well which I don't currently want. My emission are due in 3 weeks so im gonna have to ask for an extension I guess.
 

·
Registered
98 impreza outback
Joined
·
70 Posts
Well also to if you look in the selling forums or whatever its called ive gazed through there and found some guys selling them so you can try that too
 

·
Registered
07 WRX, 06 STI, 00 RS, 05 LGT
Joined
·
69 Posts
Well also to if you look in the selling forums or whatever its called ive gazed through there and found some guys selling them so you can try that too
Thanks but I actually just found out my problem may be easier than I was expecting. I had the p0420 code before I put my car in to get all gaskets replaced as well as some other stuff. So while it was in there I had the front 02 sensor replaced and the guy reccomended a defouler on the rear sensor so I did that as well.

When the light came back on after 30 miles of driving I assumed it was the p0420 but I checked it this weekend and it says p0136. Rear sensor malfunction or something like that. So im assuming I may just need a new rear sensor. Although I was wondering if it was just a glitch of some type or the guy installing the defouler caused the issue.

Anyhow as of now I cleared the code and drove about 80 miles. No light has come back yet so fingers crossed. Going to take the car in for emissions this week and hope the light stays off and passes. Not sure when its been through enough cycles though to clear the code from the ecu.
 

·
Registered
2000 2.5RS/C BRP
Joined
·
2,321 Posts
With the defouler (actually meant for spark plugs, go figure) on the stock ECU, I would occasionally get a code for "response to slow" or to that effect.
 

·
Registered
07 WRX, 06 STI, 00 RS, 05 LGT
Joined
·
69 Posts
With the defouler (actually meant for spark plugs, go figure) on the stock ECU, I would occasionally get a code for "response to slow" or to that effect.
Interesting. Thanks for that reply. Like I said I didn't pull that code until 30-40 miles after I had it installed so I thought it was strange. If the code comes back im going to take the defouler off and see what happens.

Then if it comes back again ill just replace the rear sensor. Also I did read they are for spark plugs and something has to be drilled for it to fit correctly on your 02 sensor. So I was also thinking maybe it wasn't done correctly.
 
1 - 20 of 23 Posts
Top