ECU pressure sensor voltagezs

[SIMON HOLTBY]

Ameer,

When I had my 84 UR I experimented with running higher boost. They way I
went was to use the common resistor zener mod to the ECU so that the fuel
pump did not cut at high boost.
The stock pressure sensor in the ECU if I remember correctly is a 2 Bar
unit which like most sensors gives a 0 to 5 V signal. Remember though that
atmospheric pressure (ie without the engine running) is 1 bar which gives
a 2.5 V output so 1 bar of boost above atmospheric  gives 5 volts. The
voltages were quite linear to pressure but not 100% exact  due to
variations in atmospheric pressure and limitations of the sensor. 
I used a seperate 2.5 bar sensor controling an additional injector and
adding ignition retard so I could run up to 1.5 bar boost. To control
injector dwell and ignition retard I needed to know the relationship
between voltage and pressure so I used my CO2 bottle from my welder to
provide the pressure with a pressure gague connected. As I opened the
regulator I could plot a graph of volts to pressure. The same could be
done with the internal pressure sensor if you wanted to.
The stock boost gague used the sensor in the ECU. The signal may be
modified to say a 0 to 12v signal by a simple amplifier circuit, I dont
know.
Just remember Bosch ECUs are expensive to replace if things go wrong.

Simon Holtby


--- Ameer Antar <ameer at snet.net> wrote: > is there anyone out there who
knows what actual voltage the pressure
> sensor 
> puts out at 1.0 bar? I'm trying to figure out how voltage and pressure
> is 
> related...ie. voltage at 0.1 bar or 1.8 bar, etc. My understanding is
> that 
> it's basically 0-5v, but my experience w/ electronics is sensor will 
> sometimes actually have a range of 0.1V-4.85V or something. Anyone BTDT?
> 
> Also does the stock boost gauge use the same 0-5V signal from the ECU?
> or 
> is there a different pressure-voltage relationship? Thanks.
> 
> -ameer


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