my friend has a d16y7 motor in which the cat is built directly into the exhaust manifold in case u didnt know.. one O2 sensor is located at the top of the manifold right in the middle where the four runners meet and the other is located at the bottom of the cat.. he is throwing on a different oem d-series header where the cat isnt built right into it thus having no cat on his car.. my question is what do i do with the 2 O2 sensors now that there will only be one bung in the exhaust manifold..which one do i use and what should i do about the other??.. am i going to run into CEL problems??

 

Tap the bottom of the header and put the 2ndary o2 sensor there. Muffler or auto shops won't do this for you because you have no cat and they get fined $10,000 if they get caught doing it. You can also buy a regular cat that goes under the car and have the muffler shop cut your existing exhaust pipe so it fits under there like they normally do.

 

the whole point in him doing this is so he wont have a cat and he can have a straight pipe so he doesnt want to add a cat on the exhaust piping.. and instead of tapping another hole in the header couldnt he just solder the 3 wires from each O2 together and run just 1 O2 sensor??

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jay.dee.em1 &raquo;</TD></TR><TR><TD CLASS="quote">and instead of tapping another hole in the header couldnt he just solder the 3 wires from each O2 together and run just 1 O2 sensor??</TD></TR></TABLE>

no he cant do that. primary o2 sensor changes air/fuel ratios

the secondary o2 sensor tells the ECU that the cat is in proper working order. no cat = CEL. solution is to get a o2 sensor simulator. see o2 sim install thread below for link to buy