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Rheostat - resistor ?

Mike Hainsworth

Oct 9, 2017
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Oct 9, 2017
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Simply put I wish to trick my car's ECU into thinking the turbo boost has not reached a certain level.
12 volts is supplied to a pressure switch with zero being fed to the ECU when there is no boost pressure.
As the pressure rises the switch feeds out a corresponding voltage up to 5 volts when maximum pressure is reached.
I have increased my turbo pressure (this is fine on a diesel as it will not cause a lean mixture) and it now causes the ECU to cut fuel as it recognises an over boost situation.
What can I do to limit the maximum voltage output to say about 4.5 volts?
I need the signal to be somewhere near correct just muted, i.e. as the pressure rises so does the voltage even though it is slightly lower than original.

Any help (and preferably simple) as this is for simple person and the fitting is in the engine bay of a 4X4.

Cheers

Mike
 

73's de Edd

Aug 21, 2015
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Sir Mike . . . . .

If in actuality, that pressure sensor is putting out a variable 0-5V, a voltage divider will put out 4.5 V for 5 V input or 4.05 for 4.5 input or 2.25 for 2.5 input . . .etc . . .

But you will NEVER see 5V output again as max . . . just that divided down to 4.5V at max, instead.

IF, in actuality, there is not any complex intermediate circuitry which is actually putting out a variable pulse width signal and is then dependent upon being converted within the ECU unit . . . . into being that 0-5 Vdc value.

Three different options are being given, as the lower values just may load and lower the sensor excessively or the highest values may result in too weak of an output. The middle values may be the best option.

Anatomy of a Voltage Divider . . . . .


Voltage Divider.png

73's de Edd
 
Last edited:

Audioguru

Sep 24, 2016
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Sep 24, 2016
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The ECU cuts fuel when the turbo boost is too high to prevent the engine from blowing up.
Why do you want to blow up your engine?
 
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