EFIE Range Adjustment Instructions

Important Note: The range adjustment feature has been discontinued for single EFIE models. It has proven to cause more confusion in users, than it has been of use, and it's just not needed in a modern EFIE.

Voltages above .45 on an EFIE cannot be used. If the computer never sees a voltage below .45 volts, then it will "know" that the sensor is damaged and will ignore it. So, increasing the EFIE's range is not a valid use. Decreasing the range is also not needed as modern EFIEs are accurate across their entire range of voltages. Therefore the function has been discontinued.

There are EFIEs in existing stock that will still have the range adjust pot installed, and this document will still apply to these.

Also, it has been found that Dual EFIEs require calibration, and have therefore retained the pot that can be used for range adjustments.

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Increasing the voltage range of the EFIE is not the only reason for changing the EFIE's range. If you find that you are getting your best mileage increases at .200 volts, for instance, you may want to decrease the EFIE's range to go to a maximum of .250 volts. The advantage is that the EFIE's front panel adjustment screw is more sensitive the closer you get to the EFIE's maximum voltage.

By this I mean that you can turn the adjustment screw a full turn to increase the output by 20 millivolts when close to the maximum voltage, whereas it might take only a quarter of a turn at the bottom end of the EFIE's voltage range. This allows you to set your voltage offset very precisely, more easily. However, I run my EFIE at about .225 or so, and I have never changed it's range. This usage is not needed, and I don't particularly recommend it. But for you habitual tinkerers, this can be done.

Ok, so if you've gotten through the warning section and are still ready to go, here's how it's done:

1) Adjust your EFIE to it's maximum setting. The quickest way to do this is to back off the adjustment screw until your meter reads below 50 millivolts or so. Then turn it clockwise 20 turns. When getting close to the EFIE's lowest setting the voltage drops quickly, without the time delay you experience at higher voltages. At the top end you have to wait for many minutes to see if it is at it's maximum voltage, or, if you rush it, you may turn the screw too many times and lose track of where you are.

2) Open the EFIE's case and then see the photos below for your model of EFIE, Single or Dual. Find the range adjustment potentiometer on your EFIE's circuit board. Note that the pots marked "Voltage Adjust" will not be on a Deluxe model EFIE. This is because the Deluxe version is adjusted by an external pot mounted on the box. Note that the Single EFIE in the photo has no range adjustment pot. But if a pot is in that location, that's the range adjustment.

3) Turn the range adjustment potentiometer very slightly counter-clockwise to increase the EFIE's voltage range. Note that very small adjustments to this pot make a large change to the EFIE's range. Also note that you will have to wait for some minutes to find out what the full result of your adjustment is due to the large capacitor in the circuit.

4) When your meter reads the voltage that you wish to have as the top end of your EFIE's range, then adjustment is done. Replace the back on the case.

5) Re-install the EFIE into your vehicle and be sure to adjust it, as it's currently set to it's new maximum value.