O2 sensor issues

[Scootsk]

Question: Will an O2 sensor cause a hard start issue? I did a smoke test, no leaks. Replaced Coolant temp sensor. Same issue. Hooked to a OBD I reader and it shows an O2 code. Clear it, go for a ride and after about ten minutes, runs great, then it throws the code again and the cars performance drops terribly, barely runs, complete loss of power. There have been occasions when the CEL will go out and performance returns slightly but not 100%.
When I watch the live data on the scanner, the O2 sensor started at about .45 volts at cold start. After warming up it would drop to about .25 volts. Unfortunately after about 30 seconds after start up the scanner loses communication so I can’t watch it while driving.

[sienayr]

Disconnect the O2 sensor and go for a drive. The DME will revert to canned mappings. If the situation improves then it would point to the O2 sensor causing problems. Hopefully you read what I posted in that other thread, jlevie was a revered e30 guru and he covered about everything that can cause issues in that thread.

[Scootsk]

Change the O2 sensor. What a pain! Thank goodness my neighbor owns a muffler shop. Took him a good half hour with a torch to get it out. Didn't make a damn bit of difference. It turned out to be the brand new fuel pump I installed in the car!!! UGH!