I have a 1986 944 with a 2.5 engine.Right next to the oxygen sensor there is a fitting that looks like there should be another sensor but it's caped off. Should there be something there ? Also right behind the engine on top there is a round connector with 3 pins that isn't hook up to anything.

 

Pics?

 

The other hole in the exhaust used to have a tube attached to it that runs to the top of the engine bay. I hear it was for emmisions testing back in the day.....I think most of them are capped off now days. Mine is.

The plug your talking about sounds like its the O2 plug. Is your oxygen sensor plugged in?

 

Do you have cruise control? If not the three-pin wire might be the one that originally went to the CC motor.

 

Where exactly is this connector? The late O2 sensor is a 3-lead connector.

Yeah the capped off port was once for emissions testing but everyone removes it since it became obsolete. Mine are all capped too.

 

You are seeing the cruise control connector if it is up near the front right shock tower, the other little thing you are seeing that is behind the o2 is the old emission testing port, they could sample gasses from before the cat. It is capped in almost all cars, and I know of many people (myself included) who have capped it off and had no ill consequences.