I've been getting a code 1 since installing a replacement Si motor swap, although I reused the old O2. The CEL comes on after about 5 minutes of driving and stays on.

The car stumbles pretty bad until it fully warms up.

Is this the fault of the O2 or just a coincidence, just looking for a heads up till I can swap it out.

 

That's pretty obvious. First, make sure your O2 sensor wiring is intact. If it is, get a new O2 sensor and make that code go away.

 

Just want to make sure thats whats causing the stumbling.... it seems more like a fuel/ignition issue.

 

Do you have a header that relocates the O2 sensor further down on your exhaust? Like right before your cat or something?? Cause if so it could be that its cooling off and thast what your problem is. I have a DC header and the O2 sensor is so far down that it cools off from driving and then I get a CEL and code so that might be your problem as well.

 

your car might be running too rich with the o2 sensor messed up. that might be whats causing it to stumble...

my o2 is also messed up. it will flash the code after about 5 minutes and my car runs pretty rich. the wires are fine. should i try and clean it with carb cleaner or brake cleaner or something?

 

bump, i still need some help...

 

I think I'm running ulta rich as well.. only getting 200 miles a tank whereas I used to get 300+