more musings on EFI controllers

[peter paul fenske]

At 09:58 PM 8/7/96 -0500, you wrote:
>Robert Van Zant wrote:
>      Sounds good, but I'm still looking for the hole to plug my one		|
>> must-have item into.  Limp Home Mode.  For my particular application,		|
>> LHM is crucial to the point that I've been dreaming up digital-over-		|
>> bob										|
>										|
>yeah, digital is the only way to
>go_____________________________________________|
>that is if you know what you are doing.  ANYTHING that can be
>controlled, can do with digital.  Analog is too touchy and needs TLC,
>give me digital, on, off and ADC.
>
Hi Guys
Take a lesson from GM. They use a reduntant fuel controller chip which
takes over when the digital part of the cct. fails.
This is a LSI analog chip. Calibrations are via resistor packs.
Same could be done for DIY via headers with resistors.
A simple cct would be a divide by four for ignition used to fire a
pulse width mod like the TL494. Op amps would set the Pw with a input
of TPS for load and CTC for temp correction.
Outputs are shared with digital via diode or gates.
Distributer is put into direct mode or default.
This gives fixed timing. 
Quite a simple cct since for LHM you are not interested in closed loop
operation.
Well tats my 2 cents
Have fun guys:peter