3" exhaust build
 

hi...Ive recently purchaced all the ---- i need to build my own 3" exhaust. i have a dsm and i and i dont want to spring up the extra dough for the after cat o2. is there a way i can sort of speak trick the ecu that the after cat o2 is there even though i only have the upper one? im only going to run one resionater. no restrictions.

Re:3" exhaust build
 

you can get an o2 simulator

Re:3" exhaust build
 

you can get a O2 sensor for way less

Re:3" exhaust build
 

yah just put one there.. it wont be a restriction if thats what u are worried about.

Re:3" exhaust build
 

yeah, all you have to do is weld a bung into the pipe for it

Re:3" exhaust build
 

if you have two o2 sensors, one before and one after the cat. and you remove the cat, will you throw a code?

Re:3" exhaust build
 

On my 97 ex I installed a test pipe and took out the cat, and even though I had the o2 sensor in the test pipe I had A CEL, so yes you need both and a Cat to not get a CEL. I solved it Using an OBD1 P28 and conv harness.

Re:3" exhaust build
 

The after cat O2 is in place to make sure the CAT is working. You can make your own 02 simulator with a transisor amplifier circuit (?). I'm 99% sure that's what its called. Basically the circuit would take the reading from the first 02 sensor and then split it to 2, 1 for the orignal harness, and then the 2nd is run through the amplifier which would be used to drop the voltage and then send it as if it were the 2nd 02. This simulates the catalytic burning off the excess fuel and thus showing a leaner burn. It could be like a $10 solution. I'll make one and let ya'll know if it works...

Re:3" exhaust build
 

yeah that sounds like what i need to do. im gonna weld this ---- up like early next week! ill whip up one of those simulators, let me know how yours turned out. thanks for the info.