type of eprom

[Peter Wales]

>Thanks for the full explanation. I do have a question, which others
>may be interested in.
>
>The EECIV , of which I have one of, Has a learning mode to compensate
>for changes in parts over time and to fine tune the cruise mode A/F.
>Does your adapter change any of the modes, or just the base settings.
>I've read conflicting reports about this since about 88, when the 
>adapters first started popping up.

Good question!

First let me explain the learning mode.

If the optimum fuel number for a certain conditions in the particular car is
80H and the program contains the number 78H then the computer corrects the
fuelling number by reading the oxygen sensor and increasing the fuel until
the engine is at stoichiometric. Then the fuelling number has risen to 80H
and the computer records a difference of 08H in its Keep Alive Memory. 

The next time it gets the same conditions it adds the correction to the main
number and gets the correct fuelling number quickly. This allows the engine
to tune itself more quickly. 

If we fit a chip, then the fuelling on part throttle will be unchanged,
simply because the oxygen sensor overrides all the changes we make and all
we can do is to slow down the engines time to perfect tune, which the memory
will soon fix anyway.

On full throttle the correction is not used and the system goes open loop.

So, fitting a chip will not affect the memory and it may take a little time
for the computer to optimise itself by learning about the car, but it should
have happened in 20 miles or so. 

When we develop a chip, we have to clear the memory to ensure we don't
program the car with a built in correction factor and we do power runs so
fast the system has no time to learn. Hopefully the the memory correction
will never be used on that car, but will allow other cars to optimise
themselves. As the cars age, they tune themselves to adapt for increased
wear and carbon build up.

I hope that answers the question

Peter Wales                    pjwales at magicnet.net
President Superchips Inc
Chairman Superchips Ltd        "Timing is everything"
Superchips home page with all the answers http://www.superchips.com