Cincinnati Civic VX
 

I bought a Civic VX in December and got around 48 mpg in my maiden voyage from St. Louis where I picked it up, back to my home town of Cincinnati driving it not very economically as I was making the 12 hour round trip in one day. My daily commute has averaged between 44 and 64 mpg. Quite the swing so I'm looking forward to getting more 64's than 44's.

I figure real time feedback is the best way to train my right foot.

Since this is pre-obdii I'm putting together an MPGuino (since the prebuilt has been backlogged for several months with no signs of life). If there are any electrical engineers here I'd like a little advice. I'm skilled with reading a schematic, soldering and programming but not so much with the intricacies of the electrical bits and circuit theory. I'd like to indicate when the engine is in lean burn and when it is not. The arduino / mpguino has unused analog input ports that can read 0 - 5 volts. Putting a voltmeter between D16 on the ecu and the negative lead to chassis ground runs 0 - 5 volts. 2.7 volts is stoic. Anything greater is lean. I'd like to run this into the arduino / mpguino. Can I just tap into D16 and connect directly to the analog input pin... or do I need a resistor or other bits in between? The arduino / mpguino can only handle max 40ma on the analog input pin.

Thanks in advance for any advice.