How To… Work with Signals over 5 Volts

The Unichip can read and display analog input signals from 0 to 5 Volts. These values will be displayed on the Unichip Software screen as indicated in the picture below. So basically the Unichip has a built-in Voltmeter which can display 5 Voltage inputs at the same time. The key is to know which pin on the Unichip is tied to which value on the software screen.

Important Tip The inputs will max out at 5 volts, so even if the input is 7 volt it will only show 5 volts on the Unichip software screen

Click on the images below to enlarge

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The Unichip was purposely built this way as all modern vehicles work with 0-5 Volts. Some older engines with VAF sensors use signals between 0 and 7 Volts and to control the fueling the Unichip has to be able to modify signals bigger than 5 Volts in which case you must use the TPS in and TPS out.

Warning! In older vehicles you must measure the VAF (Volume Air Flow) meter voltage output. If the voltage output at max air flow is above 5 volts then you must use the TPS channel to control or manipulate the fuel.

The TPS is the only channel that can handle voltage inputs from 0 to 10 Volts. In other words, it will output whatever the input is up to 10 volts. You can then use the TPS map like normal to add or remove fuel in the TPS map: The value you use will be added or subtracted from the output.

The biggest problem will be the load look-up since these systems normally don’t have a TPS signal. The easiest way is to use a MAP sensor like the Turbo Module for load look-up.

Alternatively you can build a simple voltage divider circuit as in the picture below which will lower the voltage output. You  can then feed the divided voltage into the 0-5V (1) Pin 6 or Fuel-in on Pin 7 on the Unichip.

Click on the images below to enlarge

 

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