[AT] O/T Tow truck OBD II question

[charlie hill]

I just bought an OBD II code reader that interfaces with my notebook 
computer.  It's pretty impressive and gives all sorts of charts and graphs 
of engine sensor operation.
I'm happy with it..... almost.  The problem is that I don't know how to 
interpret all of the data.  For example the graph generated by one of my O2 
sensors seems very erratic by comparison to the one down stream behind the 
converter but I don't know how it should look.

Does anyone know of a book that explains the parameters of the different 
engine sensors and maybe has pictures of the ocillascope (sp) graphs?  I 
finally got tired of paying inept mechanics to throw parts at a problem. 
I'm intending to teach myself how to diagnose this stuff to the extent that 
it can be done.

Charlie