Pro and con of leaving O2 sensor disconnected
 

Hi guys - I brought my '74 to a well respected shop to get their help on a surging issue that they tracked back to the O2. They simply disconnected it - and she runs better now. Any issues with leaving it disconnected? I know opinions vary here...

Thanks in advance for the coaching.

With a Motronic 3.2 I wouldn't disconnect the O2 you're just masking some problem.

I agree. Fix the real problem and hook up the O2. It will keep you engine running properly.

The sensor is cheap, replace it....it's important to the DME's proper operation.

disconnecting it will only cause it to run rich, so if that solved your problem you could be running too lean--run a search on lean running problems

so much for all these " well respected " shops . surging is actually due to being rich or of courrse the compensation is not working correctly.
O2 sensors are maintanance items anyway so start fresh and replace it, then start troubleshooting.

Completely agree,...these cars were designed and intended to run closed-loop and suffer accordingly when the oxysensor is disconnected.

Your shop needs to perform some diagnostic tests to find out what the root problem is.

one tidbit to add -- as the O2 sensor ages, the response slows down -- possible that fluctuations are due to the computer trying to compensate for slow response

the sensors last a LONG time - but are simple to replace and not too spendy; also be sure the coax cable is in good shape (I'm not familiar with the new-fangled 911s but the above is based on your typical German car of this vintage)

I can't see a pro in leaving the O2 sensor disconnected. The motronic will not get the correct signals it needs to have your engine run at best power and efficiency. The sensor is a 60K mile service item and can be changed within half an hour.

It may run better in open loop mode but i'll bet money that your fuel mileage drops like a rock.

The only way you can have a 3.2 work properly w/out an O2 sensor is to have a DME chip mapped like the European cars. Euro 3.2 engines have no provision for O2 sensor.

there is no pro to run it not connected.....well.....cost of fixing what is wrong.