I recently installed a tbe exhaust (helix dp, invidia cat-delete, and hks hi-power exhaust) . The check engine light went on after a few hundred miles. I reset the ecu after installing the setup. Should I be worried? what does the ecu for the '03 evo do now that I don't have a cat. Does it make a difference in performance? i've heard that there are some 02 emulators out there. is this necessary?

 

if the cel light doesnt bother u, u can keep on driving as is. but if it does..look into anti fouler..thats the cheapest remedy to cure the problem, cost less than the 02 simulator

 

you need to get an o2 simulator. You can get an electronic o2 sim, or a mechanical. The mechanical one will cost you around 10.00 and the electronic will be aroun 50.00

Go to your locak napa parts store and buy two anti plug foulers. Drill the forst one out so that you can fit the o2 sensor all the way through it. This requires a 9/16 drill bit. Once you have done that, screw both plug fowlers toghether and stick them into the rear o2 sensor bung and then screw in the factory o2 sensor into the plug fouler you just drilled out. This puts the rear o2 sensor back away from the exhaust, thus tricking your ecu into reading less exhaust gases. Check the How to section if this confuses you.

Here is the how to, but there are no pics at the moment. This is a very easy mod though https://www.evolutionm.net/forums/sh...ad.php?t=98573

 

how does the "check engine light" affect performance? my friend who's a smog tech says that the ecu would be running in safe mode if the check engine light is on....

 

it doesn't affect performance at all

 

it might make it run a little richer, since the ecu is thinkin your 02 sensor is shot....i've got a mechanical 02 simulator that i never used...if interested, send me a pm and we can work something out?

 

As long as the front o2 sensor is good you are fine. The back o2 sensor just measures flow from the ctalytic converter

 

Just get an o2 simulator, it works perfect.

 

sorry for bumping such an old post but i am going to add the anti-fouler to my tbe and have a hks hi-power. if you are running the hks hi-power with anti-fouler fix did you use 1 or 2 and what part number,42002 (longer ones),42009 (shorter ones)? reason i ask is with the hi-power exhaust just 1 of the 42002 is causing the sensor to hit the underbody. thanks

 

when i installed the mechanical o2 fix, it hit againsted the underbody. it was pretty long about 3-4 inches. To remedy this I simply took a hammer and knocked in enough underbody to clear the emulator with the o2 sensor installed. Everything worked fine after this.

 

gunnerman, that is what i ended up having to do aswell