HELP! Unplugged wire - causing problems when plugged in...

[jcsjcs]

Hello - I recently purchased an '84 Carrera Targa and had a full PPI completed. All came back well and I have been driving the car for the past 2 or 3 weeks - about 100 miles total. I am starting to really love it!

Today I embarked on some projects (fixed a Hi-Beam problem, dealt with a leaking tire, etc.)

I was looking around the engine compartment and noticed an un-plugged wire on the left side of the engine directly below the fuel filter. I looked in my Bentley manual (quickly) and did not see anything immediate. I saw where the wire belongs and so plugged it in.... In the driveway I noticed some strange idling (some drops and then surges.) I took a drive and the car started to surge and lull. I pulled over and un-plugged the wire and the car went back to "normal."

What is going on? Any advice is appreciated - and I hope there is not a big problem that was masked by the seller by pulling out this wire.

Pics attached - please let me know if more info is required.

[jcsjcs]

Not sure where the pics went.... so here is a link.

http://public.fotki.com/jcsjcs/1984-porsche-911-ca/imgp3013.html

http://public.fotki.com/jcsjcs/1984-porsche-911-ca/imgp3006.html

[Rot 911]

Hard to tell looking at those pictures, but I suspect it is the connection for your O2 sensor. It probably quit working correctly so someone unplugged it instead of replacing it. When unplugged your DME goes into a closed loop mode and runs a very rich fuel mixture.

One end of the wire should go to a bracket on the driver's side of the engine. The bracket has three separate plugs. The other end goes down through the engine tin and then to the O2 sensor that is screwed into the exhaust again on the driver's side.