I had issues with passing smog a few weeks ago due to high HC at idle. I was able to pass (barely).

I just replaced my MAF and am going to try to replace my wide-band O2 sensors per someone's recommendation.

I've had a few CELs thrown that cleared up after unplugging the battery. The CEL came back after roughly 500 miles of driving.

I finally got Kevin@UMW's data-logger but didn't see any stored codes. I thought you needed to unplug the batter for 10 minutes to clear stored codes?

I've got a Speedtech exhaust that I've only had on for less than a year so I doubt the cats are bad.

I'm a newbie to logging. Are there specific values I could log/read at idle that would let me know whether replacing the MAF and O2 sensors have resolved my high HC at idle issue?

I've read that Lambda Bank 1 is for pre-cat O2 sensors but what values should I be expecting at idle for properly working sensors?

Thanks

 

If you cleared the codes you'll have to wait until they come back. Next time codes are thrown, you can read them to see what they are specifically. Sounds like 02 sensors or a leak in exhaust somewhere causing a difference in the what the sensors expect to see and what is going across them. The high HC could be from motor running rich trying to adjust for lean conditions that are present somewhere. Check for cracks in your exhaust especially around the area of the cats and 02 sensor.