Some thoughts and questions on EFI

The_Mechanic efrank at
Fri May 6 02:43:50 GMT 1994

This is great.   Perhaps we should all set up some sort of "standards" or 
at least a list of reference measurements like Dirk listed below?  

This way, all work would be complimentary and mutually beneficial.  

A couple of quick questions (from an electronics-ignorant ME type guy):

- the 68HC11 microcontroller chip is an 8 bit unit, right? Is there a 
similiar chip available in a 16 bit architecture?  Would it even be 

- it would be great to develop a system with some accompanying software 
so that a laptop PC could interface "Real time" with the engine computer.  
Adjustments could be made "on the fly" with the engine running.  This 
would be wonderful on the dyno.  Also, an interface that would port 
information over to the Superflow SF-901 software would also be real 
cool.  Are these out of reach?

I think its already time for some sort off FAQ/STANDARDS/REFERENCES type


On Thu, 5 May 1994, DIRK BROER wrote:

> Before we decide on what computer to use etc shouldn't we decide what the 
> operating enviroment or rather the requirements are?
> Ouput would be a PWM signal to the injectors.  You could vary the start 
> time and the end time of each injector to get sequential port injection.
> For input I suspect we'd need:
> O2 sensor - what better way to set the car for part throttle cruise.
> Throttle Position sensor 
> temperature sensor
> RPM sensor - maybe an engine position sensor - so you know exactly which 
> cylinder needs fuel / spark next (distributer mounted of course).
> and then either a MAP or MAF sensor.
> maybe Humidity sensor? - or altimeter?
> Is that all?
> If that is all perhaps we could also get an idea on what kinda of data 
> rates are needed.
> 02 sensors react relatively slow - maybe 10 readings a sec?
> TPS - sensors - at least 10 readings a second if not more
> Temp sensors - 1 reading a second
> RPM sensor - at 10,000rpm (why not?) - that 600,000 degrees per second.  4 
> bumps on the crank shaft (ie - crank triggered ignition) would mean less 
> than 1000 per second...
> MAP or MAF sensor - 1 per second - maybe  more... 10?
> The system would have to work at:
> Startup
> Idle
> part throotle cruise
> anything else?
> Next post  what would the algorithm be like?
> Dirk

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