Fuel air mixture meter/tool recommendations

[tonyduc]

All

I looking to adjust the idle mixture and have seen posts that mention use of the LM-2 meter to measure CO in the tailpipe. The reading should be between 2.5 and 3%. However, the LM-2 and NGK tool manufacturers only mention having an O2 sensor. Is % CO derived from this measurement or is a CO sensor necessary ?

Thanks
Tony
1977 911S

[911obgyn]

I use an LM2 gauge and wide band O2 sensor to set base idle and CO on my 3.2. I remove factory O2 sender and have power clips wired to gauge. Have not installed it in the car because i use it for other cars. Needs to be B4 cat for proper reading.

[fanaudical]

Here's a link to a CO% to AFR conversion table that has been referenced previously on this site:

https://www.mgexp.com/article/co-to-air-fuel-ratio-afr-table.149#utm_source=alias&utm_medium=mgexperience.net

[tonyduc]

Thanks, the conversion is what I looking for.