Any one seen these DIY gauges?

[ECONORAM]

Originally Posted by diesel_john

I have a digital A/F meter that shows me the magic 14.7 number. I got it because I wanted to "see" what an EFIE (02 sensor signal modifier) would do. But, when the EFIE is off, the A/F ratio is pretty much bouncing above and below 14.7, so it's not doing much, just like you said.

CarloSW2
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How does this EFIE work? What does the circuit look like? I once played around with the O2 voltage by just adding 0.2 of a volt to the signal with a 3v battery and a simple $5 voltage divider circuit and it gave me a mile per gallon or more. Did not check the placebo effect. Newer ECU's are harder to fool.
diesel

I have considered rigging up a little circuit to do this very thing. I was a little concerned about the A/F ratio when I did this, however. As I understand things, going a little more lean should not be a problem... This method would beat spending $75 for a EFIE gizmo.