Re: Fuel Enrichment Device

[brads@mindspring.com (Brad Sheridan)]

>I believe that the Autotech device will modify the control current to the
>regulator at different RPMS, and not just under full throttle, at least that's
>what their write up on their web page implies.  They make a big deal out
>of their RPM sensing capabilities.

  I wonder why they make a big deal of it? The reverse engineering info I
saw made it appear that all it does it sense the RPM, and not turn on until
a certain RPM is hit AND the WOT switch is closed, no big deal there. RPM
switches take a few minutes and a dollar or two in parts to make. If you
wanted to make the enrichment vary with RPM, that'd be simple also. Use an
LM2917, one as a RPM switch to determine when to turn it on, the other to
determine how much current is sourced based on RPM.

>> It did it in a very simple way. I had some ideas on how to
>> improve the design, I've just got too many electronics projects going on at
>> work to start up another one at home. But basically, instead of going to a
>> fixed enrichment current like the Autotech module, just add an adjustable
>> current source in parallel with the DPR wiring.
>
>You don't really want to do this, because you have no way of checking the
>fuel/air ratio.  That's why the mA rating from the EC article is so important.

You can simply check the DPR current. If the OXS computer is sending 15 mA
to the DPR, you add another 5.5 mA to it so that the sum is 20.5 mA. This
way, as the cars sends different values, based on engine temp, and whatever
else it takes into consideration when figuring the DPR current, you're just
modifying it by a few mA to move the AFR from what the computer thinks is
best to what you think is best. Otherwise your 20.5 mA may be a little lean
when the engine is cold, and/or a little rich when its hot.

Brad


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