hi all, i just posted in the main mitsu exhaust forum, then realized that the activity there is only like once every week, so i'm re posting here -
I installed a cat-back exhaust and high flow cat on my 99 eclipse GS (NA auto). right after that, the check engine light came on. i can't pull codes, so does anyone have any ideas for a fix? is this common after installing a cat-back and cat?

 

The rear o2 sensor is picking up less gases instead of the normal backpressure of gases that it would normally pick up....normal with catback install on most applications. TheEngineer has a write up on moving the o2 farther away from the gas stream in the DIY section. It's either that or your rear o2 is bad, lol.
You can reset the computer by disconnecting the battery and then pressing the brake pedal for several seconds and then reconnecting the battery and see if it pops back up.
You can also get the codes read at Autozone for free. I bet it's about the rear o2 or the EGR system, which the cat is a part of and which the primary reason for the rear o2 is to monitor the cat.

I just saw your other post and you've already reset the ECU, so the next step is to take it to autozone just for poops and giggles and to pull up the code and have them reset it. If that doesn't work, go to the DIY section and look for T.E.'s write up.

 

thanks for the info, i'll hit up autozone tomorrow to pull the codes.

 

yep same thing happened to me!! After I got rid of my cat (got 3" piping all the way back, down pipe to exhaust) and mine started coming on.. and smelling a lil funny at first. I took it to my friends' shop and he checked it out and said sammmmme thing. o2 sensor. so he turned off the light and i've had no problems with it lol.

 

ok, the funny smell your talking about, it smells kinda like raw gasoline and exhaust mixed but not as harsh right??? cuz thats the smell mine makes.

 

NVM!

hehe.

 

yep the very same.. it was mostly exhaust smelling so if you're smellin a lot of gas maybe have it looked at but yeah sounds like the same deal. See THIS is why i love this forum!! IT turns out other people have these issues too!!

 

^Yep yep. Just reset the ECU so it can self learn, and you'll be sailing.

 

ok i reset the computer again, this time i left it unhooked the whole time i was changing the oil (about 20 min). when i fired up the light actually stayed off!! i've got a 200 mile trip tomorrow so i'll post the results, whether the light came back on or not. thanks everyone for all the feedback so far!

 

Hey guys my 98 gs has the catback installed and it says i have to move the o2 sensor back. I was wondering how far it has to be moved back. I can't get my car inspected until i get the o2 sensor moved back. Please help!