A day well spent! but.. O2 sensor issues

[ejp2fast]

Well today I got the festy running.. this morning first thing connected the rods to the crankshaft (used plastigage), put oil pan on, timing sprocket, my head was already done and ready to go, intake and exhaust manifold,timing belt, and air intake stuff. Added fluids and had it fired off at 5:30p, and she ran like a charm!!! a lot better than 3 cylinders when it quit 4 months ago.

Ran it as specified in my trusty haynes about accel to 50 nph and decel to 30 mph etc....

One thing is after running a while my check engine light came on and i ran the codes when i got home and they are 15 and 17. O2 sensor info for both... this didn't come on before it quit...??? any way to check to see if the O2 sensor working properly before I go and buy one?

Finally just put a day aside to work on this lil beast and now its a going!
Then I had my cheapo sunpro II tach from autozone and got it installed as well! Still need to adjust my idle speed though. When i am up to temp and the hood is open my engine does a very mild surge...? increased rpm like 50 ish..at about 2 seconds frequency. any suggestions?

[b8kedbeans]

The o2 sensor may not actually be bad, sometimes moisture and fumes from solvents and other contaminants will make the sensor malfunction. After running it for a 30 minutes or so the check engine light may go off and stay off. Please disregard this if you have already run your car for a bit at normal operating temperature

[ejp2fast]

started it and ran for a while this morning.... no check engine light yet...

[jglutz]

The +/-50 rpm change at idle could be the O2 sensor....I would reset and give it another hour or so of running...waiting for contamination to burn of could be the problem.

[Axlander9289]

Backprobe your O2 sensor connector (located on the radiator support) with a straight pin and check voltage from there to ground with the sensor plugged in and the car running. Proper voltage once its warmed up should be around half a volt if its not running too rich or lean, and the voltage should be constantly switching within a couple tenths of a volt in either direction

[ejp2fast]

my check engine light hasn't come on for 3 days... good sign. guess a little contamination on initial start up was the issue.

Backprobe your O2 sensor connector (located on the radiator support) with a straight pin and check voltage from there to ground with the sensor plugged in and the car running. Proper voltage once its warmed up should be around half a volt if its not running too rich or lean, and the voltage should be constantly switching within a couple tenths of a volt in either direction

Thanks Axlander9289.