Performance exhaust and O2 sensors

Install O2 sensor bungs where you need them and screw your O2 sensors back in.

 

+1

 

Best to place them as close as possible to the engine where they can sample the mixed exhaust gases from all 6 cylinders in the bank. Some aftermarket systems are built in a way that only allow a location sampling 3 cylinders in each bank, and that can quasi-work. Do you have a photo of the system?

 

Here's a manufacturer's recommendations for their system. The recommendation about mounting the sensor upstream of the air pump will be difficult to comply with for our cars, however, but fortunately, the pump operates only for a minute or so after startup.

Conventional wisdom is to mount each UEGO just after the merge collectors on each side of the engine as Steve recommended.
Image Unavailable, Please Login

 

I guess your "test pipes" were not provided with bungs. You can put them approximately where they would be if the cats were installed. One of the considerations is how much into the exhaust stream they intrude. They have to be far enough in to get a decent sample but not enough to impede the flow. Sometimes people make up for this with wider test pipes.

 

If you have no catalytic structure at all in the exhaust stream (i.e., no precats and no cats), any overtemperature indication must be a false indication -- either wacky warning light ECU(s) or bad thermocouple connections. Are you saying that your aftermarket system does have fittings for mounting the thermocouples in the exhaust stream, but no fittings for the O2 sensors (which is a little odd), or do you have the precats present and the thermocouples in the precat fittings? If the thermocouple ends are not mounted in the exhaust stream, that would also prove that you are just getting a false indication