I just put in a simple circuit to bypass my rear O2 sensor. The circuit makes the ECU only see the last image captured into the ECU , of the O2 seeing clean air. You don't need to mess with the front one because it only runs the engine. I did this to the rear O2 to keep the ECU from trying to reset itself. Most of the Scions on here running the Cam-Con know our ECUs try to relearn stuff all the time. The rear O2 only has one main job and thats clean air. If it gets a really wierd reading then it will throw eveything into limp mode and throw a check engine light. Now if I change a setting on the Cam-Con telling it to richen it up the ECU will not try to fight it.

 

thats cool im really enjoying learning off of you guys experiments makes my life a little easier

 

Sweet

 

that makes sense to me. but when the ecu tried to relearn, what did it do to interfere with the camcon?

 

actually the rear O2 sensor tests the efficiency of the catalytic converter by measuring the air after the cat and comparing this to the front O2 sensor

it does not come on until the car is in closed loop

 

yea...the camcon should normally override the settings of the ECU and alter the A/F ratio, but thats when you start throwing the CEL's...I plugged in my OBD sensor today and magically had 3 new codes pop up all having to do w/ my MAF sensor not being able to adjust for the amount of air being blasted into the throttle body.

 

Sorry but this is somewhat incorrect. The ecu does look for clean air but does not use the first sensor and second sensor to compare readings. The ecu has set parameters it has low and high voltage parameters. If the you try to trick the car b/c you don't have a cat or use antifoulers/o2sim then you might set the cel due to the o2 sensor voltage being too low. If your cat is bad or you don't have one then you will have really high voltage and the cel will be set for Catalyst below threshold code.

 

so how do I go about doing this override, I am not running a cat. and I have CEL, TRAC OFF, and VSC lights that stay on. Car runs fine, I think it is running a little rich though, sometimes I can smell gas at the exhaust tips.

 

try a o2 sim. What kind of car?

 

04 xB