[massmike]

Looking for some help to solve a problem I have been chasing for a few months now. Car is a 1982 911SC with a 3.0L and the original CIS system. My issue is when the car is running in closed loop there is a light surging at cruising speeds. The surging can't be seen on the tach but I find it incredibly annoying to drive it like this. If the O2 sensor is disconnect the surging completely goes away, so I believe this problem is limited to the Lambda system. I do have an LM-2 wideband connected and with the O2 Sensor disconnected I see 14.3 - 14.5 while cruising, O2 sensor connected I see it jumping between 14.3 and 15.3 at the same RPM and speed range.

I have replaced the O2 sensor and the FV relay, both made no difference. I have also adjusted the mixture several times with no noticeable change in the surging. I am thinking possibly an issue with the Lambda ECU??

Any help would be greatly appreciated.