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Old 11-11-2007, 01:33 PM
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Location: Round Rock, TX
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Quote:
Originally Posted by Brett San Diego View Post
Jeff,

I'm having what I think are identical issues with Bank 1 on my 97 S600 sedan. I have an O2 sensor, which I think is the pre-cat sensor, that is flat-lined at low voltage. I'll have to hook up my scanner again and re-confirm which sensor it is. New O2 sensor did nothing to the bad signal on the OBD2 scanner. Swapping MAF's and O2 sensors between banks did nothing. I'm close to beginning the hunt for the root cause of this problem since I'm now having a high, surging idle issue that began with removing and cleaning the throttle bodies. grrrr. That was supposed to be a good thing to do, but it seems to have caused some problems...

Brett
Thanks Brett for chiming in. Yes, it sounds like we have similar O2 Sensor behaviors, though in my case, the engine performs great. My low O2 Sensor is Bank 2, Sensor 1; should be Driver's side, pre-cat.

Through a series of PM's with forum member myarmar, I am following a theory that maybe the O2 Sensor is operating correctly and attempting to compensate for a very lean condition – i.e.: a vacuum leak. Armed with a vacuum schematic and some wiring diagrams, I am plodding through connection-by-connection. I’ll be reporting progress in a day or so, as some of the vacuum lines have become quite brittle; breaking as I move them. As we know, the V12 compartment gets very hot through normal operation. As a preemptive measure, I am going to replace all the small diameter vacuum lines tomorrow (Monday); assuming I can get the appropriate sized tubing. I also want to swap the MAF’s to see if the problem moves to the other bank, but have to make vacuum repairs first.

Cheers,
Jeff
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