I am in the process of replacing my O2 sensor. In perp. of doing that I soaked it in dw40. While in there, I have noticed another plug just down stream of the sensor that in my case just has a cap nut. Does anybody know what was supposed to be there? Also while unpluging O2 sensor wire (rear of engine, top plug), I noticed another plug that has nothing plugged in to it. It is mounted on the engine lift hook, rear of the engine next to valve cover assembly. I am also wandering what that plug is for and if the two are related?


The car runs fine, passes emissions (barely HC 118 act, 118 max), Idle wonders by couple hunder RPM in several minutes, and seat of the pants tells me it is a little underpowered compared to stock...

Any info will be appreciated.

Thanks.

 

Just a "sample port". Most of the tubes that lead from the engine to the port on the exhaust have broken so people cap them.

Not sure about the other, I think it may be a diagnostic tool hook up port for the DME, but again not sure. (I have one too)

 

The plugged tap in the exhaust is for upstream sampling of the exhaust. The unplugged connector is for Bosch diagnostic equipment. Neither is a reason for concern.