83 Wagon Fails Emissions

[zboot]

CO too high usually means the motor isn't warm enough to switch to closed circuit, which also means the O2 isn't online. The high altitude thing may shut off the O2 sensor info as well. Not sure. A voltmeter will tell you if the O2 is working or not. I used to use a sweep meter and it would flip back and forth pretty fast. (like an on/off switch)
   I cross wire the dist to make it backfire and that cleans out the idle tubes. Dirty motor oil raises the CO as well. I temporarily plugged the PCV on mine and rerouted it to the ground for the test.

Yeah, the O2 sensor issue was that the entire sensor was rusted out. Essentially all I had was a small amount of sensor housing left. There's too little metal left to grip onto so my option now is to use a bolt extractor and/or left hand drill bit to get it out. I've got time to try and remove what's left (I've got a low profile angle head drill on the way) and put in a working sensor. I also need to do an oil change so that should help. Given the improvement between my first and second test with the CO numbers, I'm pretty confident that I can get it to pass - either by actually fixing the problem or with a combination of the workarounds you and others have suggested.

[mo.eagles]

 zboot , just ran across a TSB in the shop manual  that says when you add the high altitude jumper (with auto trans) to change ignition timing to 16* BTDC . Just thought you would like to know.