using spark plug anti foulers will "trick" the ecu

[bad2127]

My headers and cat back exhaust just came in today and this weekend we're gutting the cat and muffler so I can get a similar loud and deep combo that my friends WRX has (we gutted his too). Funny thing is that I haven't even passed my emissions yet because of a misfire and CEL issue (which I'm also fixing this weekend)
Apparently, I've heard that using spark plug anti foulers will "trick" the ecu to not throw any codes or only rarely throw them after I gut the cat.
Has anyone tired this or has it working on their car now? I'm already going to do it so I just want to some feedback.
Thanks

 

[chico904]

Just a heads up, your car will never come close to sounding like your friends WRX. I would advise against doing it, being that you want a little backpressure, as well as you dont want that "buzziness" sound in the upper rpm's. What cel are you throwing?

 

[bad2127]

last time i checked it was that I'm running lean. But I've got a misfire and a vacuum leak (most likely linked).
And I'm not sure on the specifics on how the exhaust system is going to work, my friend who's helping me is the certified mechanic so he knows the deal better than I do. It'll be a shop quality job, not a backyard project so I have confidence. And I know it wont have the same sound as the boxer engine...I could only wish.
I wont know if im throwing any other codes till I get back to the garage saturday when we do the work.

 

[chico904]

No my point is that you have a N/T. You want some backpressure, and with gutting your muffler and cat, you will essentially have a straight through exhaust, and will lose a good bit of your low end power, along with it being very "buzzy" in the upper rpm's. I'm telling you this from personal experience with my old N/T.

 

[bad2127]

I see what you're saying, and the one I ordered is already a straight thru. so it would just lose even more low end power if I gutted it too.
So then with the 2.5 inlet and 4in tip, if I take the silencer out do you think I'll get a good enough sound?

 

[chico904]

Sound wise, it will definitely sound better without the silencer, with the silencer in, my car was literally whisper quiet. Same for my turbo car. However with that silencer in I noticed a pretty noticeable difference in low end torque, compared to it being out. Obviously you want to hear your exhaust, as we all do, so I would leave that silencer out, but I wouldnt gut the exhaust and cat anymore. When you get the exhaust, leave that silencer in, then take it out, and you will see the difference. By the way what exhaust did you get, or are you putting one together at a shop?

 

[dsm612]

Gutting your cat will make you lose HP but if this is what you are going to do test pipe will make you HP keep in mind your car need back presser.About 2or3 copes ago Import tuner tested this on a dyno i am sure if you go on to there page and look at past issues you can find it.

 

[daygloworange]

If you search this forum, you can find information about how to use the appropriate combination of resistors and capacitors to wire up your 2nd O2 harness to trick your ECU into getting a 'clean' signal. I can't remember what the values are, but I did it and it worked. You gotta house the whole thing in something that can handle some head though, because the resistor is going to dissipate about an amp of current.

 

[bad2127]

If you search this forum, you can find information about how to use the appropriate combination of resistors and capacitors to wire up your 2nd O2 harness to trick your ECU into getting a 'clean' signal. I can't remember what the values are, but I did it and it worked. You gotta house the whole thing in something that can handle some head though, because the resistor is going to dissipate about an amp of current.

thanks, i just got my parts and a 4 inch tip is bigger than i thought but I just picked up 2 spark plug non foulers to hook up to the ends of both O2 sensors (checked the thread 18mm) to act as spacers to "trick" the ecu into picking up a clean air flow. I just buy the parts and figure out what to do with them, my mechanic does the fabrication so i'll leave that up to him.

 

[bad2127]

Sound wise, it will definitely sound better without the silencer, with the silencer in, my car was literally whisper quiet. Same for my turbo car. However with that silencer in I noticed a pretty noticeable difference in low end torque, compared to it being out. Obviously you want to hear your exhaust, as we all do, so I would leave that silencer out, but I wouldnt gut the exhaust and cat anymore. When you get the exhaust, leave that silencer in, then take it out, and you will see the difference. By the way what exhaust did you get, or are you putting one together at a shop?

its just a cheap $120 ebay exhaust, I work with what I can you know. But its a straight thru with a 2.5 in inlet and 4 in tip. I also got headers to complete the whole deal. Thanks for the help, I probably won't gut it now, but im not doing the work till saturday so im going to see what else i can do.

 

[2qik4u]

no matter who does it punching out the cat and muffler is a back yard quality job! if you want a different sound you should go with a different muffler!!!! there is no shop quality when it comes to breaking parts to modify them!!!! just my opinion!

 

[cmw2616]

Unfortunately, a talon or eclipse will never come close to replicating the sound of q Subaru. They get there deeper sound from the boxer engines. The exhaust manifold is of unequal length and that's how the signature sound is created.

 

[krackit]

My headers and cat back exhaust just came in today and this weekend we're gutting the cat and muffler so I can get a similar loud and deep combo that my friends WRX has (we gutted his too). Funny thing is that I haven't even passed my emissions yet because of a misfire and CEL issue (which I'm also fixing this weekend)
Apparently, I've heard that using spark plug anti foulers will "trick" the ecu to not throw any codes or only rarely throw them after I gut the cat.
Has anyone tired this or has it working on their car now? I'm already going to do it so I just want to some feedback.
Thanks

just wondering...if you haven't passed emissions yet, removing the cat probably isn't going to help you?