Mitsubishi ECU

[Joel A. Robinson]

Hi,

This is my first post to this listserver, I haven't even gotten a taste 
of exactly what is discussed here, so here goes...

I have a 1984 Dodge (mitsubishi) Colt Turbo GTS.  This vehicle has 
throttle body fuel injection, controlled by an ECU of course.  I have 
increased the boost via a check valve on the wastegate actuator tube and 
have made a few other less rewarding ($/hp) modifications as well.

The stock ECU limits maximum boost to 9.5 psi by cutting fuel after that 
point.  I have learned of a trick to fool the MAP sensor's taddle tale 
signal by momentarily disconnecting this wire when in boost by means of a 
GM no-oil-pressure = no-start switch.  I haven't implemented this trick 
but I would like to in the future.

I have some questions that you folks may be able to answer about 
increasing the richness of fuel mixture in case it begins to lean out in 
the higher boost ranges.

	1.  How can I easily monitor the A/F ratio as I drive? I have an
	LED bar graph guage that taps into the O2 sensor wire but I would 
	like to know if this guage works for all engines regardless or if 
	it was designed to work with only certain O2 sensors that operate
	in a specific voltage range.

	2.  If I find that I am indeed running lean in high boost (very 
	dangerous condition I understand) what are some easy ways to 
	trick the ECU into giving me more fuel, assuming that my injectors
	aren't already wide open?  In the repair manual written by Haynes,
	it gives the voltage ranges that come out of various sensors like
	the coolant temperature, altitude, and some others that I can't
	remember.  Can I put a variable resistor inline with these signals
	to trick the computer into thinking its still cold?  How well do
	these type of mods work?

	3.  For my own curiosity, I would like to know how easy it is to
	interface a notebook computer with some of the wires on your ECU
	to monitor the various data inputs and perhaps do some graphs of
	these signals to view how they respond to one another.

	4.  Finally, I would like to know how companies like SuperChips
	and StarChips, etc. modify ECU's.  Do they buy used ECU's and
	actually reprogram them or do they start from scratch or what?
	I haven't looked inside my box, but I don't think there are any
	removable EPROM's like some GM cars have.  Would reprogramming
	my fuel curve involve learning the assembly code for whatever
	chip is inside my ECU and making tweaks or what?

Thanks in advance for all your input!

Joel Robinson
robinj at src.usbm.gov