Cel comes on after non fouler adapter

[manifestoid]

I have a 01 mazda protege es AT and i have an obx header on and an AEM SRI.
I did the non fouler trick after putting on my header and it worked for awhile. Then it came back on. I was getting 28 mpg but now i'm only getting 24-25. I checked my CEL and i don't remember the exact number but it said fuel system too rich. How can I permanently fix this?

[niky]

If it's running too rich, your O2 sensor is reading too much oxygen. There may be a leak in your O2 fitting, causing it to read too much oxygen and running rich. Check that everything is tight.

Or it could be reading too little O2 and panicking about it, thinking it's drowning itself. If your exhaust doesn't smell like it could spontaneously combust, then it might be this.

[slavrenz]

I have a 01 mazda protege es AT and i have an obx header on and an AEM SRI.
I did the non fouler trick after putting on my header and it worked for awhile. Then it came back on. I was getting 28 mpg but now i'm only getting 24-25. I checked my CEL and i don't remember the exact number but it said fuel system too rich. How can I permanently fix this?

You should find out exactly what the code is and post it here. Are you sure you did the nonfouler trick on your rear O2 sensor? To my knowledge, fuel trim data only comes from the front O2 sensor, so there's a possibility that maybe you damaged it while working on the rear sensor as well.

Or it could just be a coincidence. We need the code to really help you, though.

[ucMP3]

Pics & codes needed.