I am looking for suggestions on the least expensive way to monitor my A/F ratio on the street. This is not something I am looking to run all the time - basically I want to monitor my car under a number of circumstances to make sure the ratios are good. Then I plan on pulling the system out.

I could go with something like this: Innovate Motorsports Wideband LC-1 LC1 O2 Kit 3769: eBay Motors (item 230493821231 end time Jul-29-10 21:48:51 PDT)

The issue being how to I then log the A/F against RPM?