First off, I'd like to say that MAP enhancers scare me and that fact is the main drive for this project.
Why do they scare me?
MAP enhancers come mainly in two flavours, single pot and dual city/highway pot. They are usually made from standard potentiometers with nice, easy to use, turn knobs and, from what I've seen so far, people without enough knowledge like to fiddle with them as if there is a label on them saying "Turn me this way for more MPG". Without an EGT gauge, this is a dangerous activity (as is any A/F ratio adjustment). I particularly remember a video higherpoweredh2o posted mentioning a customer who damaged their engine *TWICE* by over zealous cranking of their MAP enhancer.
The problem, as I see it, is that MAP enhancement needs to be proportional to engine load. Higher engine load, such as acceleration from standstill, should use minimal enhancement in order to prevent hesitation or, even worse, pre-detonation. Higher enhancements at average to low load are possible (with an eye on the EGT gauge).
A dual city / highway MAP enhancer goes some way to addressing the above, but still requires driver intervention to flick the SPDT switch over and those two nice big shiny "MPG" knobs are still there to tempt you.
The circuit I'm working on (at the breadboard testing stage at the moment) is designed to work with the more common 5v MAP sensor and has three screwdriver operated "set them right then forget them" multi-turn potentiometers:
1) High Load Enhancement
2) Low Load Enhancement
3) Load Threshold
The circuit compares the incoming MAP sensor signal to determine if the engine load is above the set threshold or below it. If the load is above, the 'high load' enhancement is used. If the load is below, the 'low load' enhancement is used. In addition, if your EGT gauge supports a separate warning light alarm, there is provision to wire this signal to the circuit and cut out all enhancement in the case of a high EGT warning.
As I mentioned, I'm still testing this circuit on breadboard at the moment, but would welcome any input (positive or negative) anyone may have. If the project is successful, this circuit will be released as open source.
Russ.