NIStune TYPE 1 V.3.5 - Manual (Page 28)

Nistune Type 1 Hardware Installation Page 28 of 33
9. Upgrading ECU MAF hardware
Early model engine control units such as Z31, R31, most HR31 (1985-1988) and VL Turbo use a
2 -7 volt hotwire airflow meter. These air flow meters then have their voltage converted to 0 - 5
volts for the internal microprocessor using what is known as 'opamp' circuitry.
The later model ECUs and airflow meters all work on 0 - 5 volt circuitry.
When installing a later model mass airflow meter from a later model vehicle to one of these earlier
model vehicles, it is necessary to modify the ECU hardware to handle the difference in air flow
meter voltage.
This is done by either altering or removing the circuitry path via the opamp, and then limiting the
maximum voltage using a zener diode. These instructions details the steps to take when
modifying the ECU
Further instructions regarding MAF pin outs are available in the Software Users Manual.
1984-1986 CR31/Z31/VLT
1. Locate the op amp surface mount board in your ECU as pictured below
2. Remove pin 14 on RHS of mini board from the board. Do this by applying heat to the top of the
connector and then pushing away from the mini board with a flat blade screw driver.
Note: It is not necessary to completely remove the pin from the ECU, as long as the pin is pushed
back and no longer touching the opamp board.
Note: Previous zener diode modification when using this method is no longer required.
3. Rewire the AFM as per pinouts in the AFM wiring document on the Nistune website