On my 97 3.4L tacoma, i've got one O2 sensor on my down pipe and one that is supposed to be after the cat. But i have no cat. Would this make my truck idle higher and do i need to get a cat now?

 

Im not sure if it would idle high or not. The missing cat would cause the O2 sensors to essentially provide the same voltage readings to ECU. This in turn could possibly make ECU think the cat isn't hot and doing its job, so ECU idles engine higher? I don't think this is the case, but it is possible maybe. Generally, the ECU will monitor engine sensors and base idle off these signals. And if there is a problem between O2 sensors, it will trip check engine light.

My thoughts anyway...

 

okay thanks. I pulled a PO141 And a PO125 out of it today. going to keep hunting