What would make an EFIE not work?

[sjrobinson]

Although Ive posted this before theres an update...
As many saw in my other posts I was having issues with my car. I think they were vacuum issues cuz I did a manifold swap and the car is doing much better. But when I hooked up the EFIE before with the problems it wouldnt work. Before I go through the trouble of putting it back in. What would cause the EFIE not to work if it was installed properly?
Im thinking it would only be o2 sensor issues but they seem fine but they're the only thing the EFIE would interact with. Can I have a bad upstream sensor and not have a CEL?

[Nadasive]

Maybe this will work?

http://www.hhokitsdirect.com/mileage...-generator.php

I'm a noob so don't take my word for it. Do some research about em tho, I don't know if you know about these chips or not but they seem like it'll help you.

[Thunderball]

You could have "worn" O2 sensors that are reacting slowly. If you have 80k or more miles, they're probably worn at least. In working with my HHO system, I installed mine at 140k....I just put new O2 sensors in so that I knew for sure I was getting good reading from my sensors. Without the HHO, I actually gained 1mpg with new sensors, meaning mine were worn. I never got a CEL either.