[Diy_efi] Re: new EFI controller

Alexei Pavlov alexis.pavlov at st.com
Thu Mar 13 09:33:28 GMT 2003


cell at x-dsl.hu wrote:
> 
> Hi Alexei,
> 
> >> Anyway, I cannot find a reason to connect T3 collector
> >> to GND instead of 12 V.
> >
> > The reason could be that you drive a current through the power
> > supply which is not ideal and has internal impendance. So
> > you'll have voltage drop on supply, which will induce additional
> > noise in an already noisy system.
> 
> NO! NO! NO!
> (noone looks at the actual circuit ?)

I did it.

> 
> The other end of the injector is connected to 12 V,
> _NOT_ GND.

Of course, because we always use pull-down actuators as N dopped
Silicium has less resistance than the P one.


> So it's exactly the other way around!
> You're driving through the supply if you connect it to ground.

Of course, energy must come from somewhere !
But did you scope the power line on a running car ? You can SEE all
ignition AND injection events on the line. In the wav file of MAF
output I've sent you there are voltage spikes on the MAF output signal.
MAF is a complexe circuit with op-amps and Temp/voltage
auto-compensations.
Don't say it's ignition high voltage:  I have a static 4 coils ignition,
the MAF is FAR from the ignition amplifier and wires (which are under a
alu cache).

Note that I did not say that this would improve injector
opening/closing time.

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