i heard o2 sims being bad could mess with the timing? i have one bad and my car is a dog. im gonna be picking up tuner cat and dyno tuning it so they will be deleted. is there any truth to this

 

Have never seen any data that would support that claim.

 

Is there an SES light on? I believe the only purpose of the sim. is to provide a dummy signal to the PCM letting it know there is a functioning catalyst there. It sounds like you might have another problem.

 

yes the light is on, with the autotap i get a code for no activity on the right o2 sim. i heard when the light comes on it goes into a limp mod that could cause you to lose power? anyways im gonna dyno tune with tunercat and watch the autotap to see what happens

 

Like this one, not all DTCs cause a change in performance.

 

"Limp Mode" is seriously misunderstood. That level is reached only with near total failure of the PCM control system inputs. Few people ever experience it. In most cases, the PCM wll either default to an alternate system of near-equal capabilities (loss of MAF forces the PCM into speed-density mode) with little or no impact on performance, or use a programmed table of values (e.g. - failure of knock sensor circuit causes the PCM to use a table of knock retard which is derived from things like TPS and MAP values.) with some appreciable impact on performance.

I have never seen any indication that a failed post-cat O2 sensor would create performance problems.... but I'm only familiar with the LT1 system, not the more advanced LS1 PCM.