Can someone explain the saturated injector to me?

High Impedance (saturated) vs. Low Impedance (Peak and Hold)

Saturated injectors have a typical input resistance (using an ohmmeter) of 13 to 18 ohms. The injector driver is simply a switch that turns on and off battery voltage, and is .7 to 1.1 amp throughout the pulse.

This arrangement takes about 2 to 3-milli sec. to turn on and off and leads to somewhat less accurate timing of the injection. Because of the strength of the magnetic field, the injector is more sensitive to fuel pressure.

Peak and Hold injectors are typically 2.5 to 4 ohms input resistance, and have to use a special electrical driver that provides full battery voltage (14 V) for 1 to 2 sec. then for the remainder of the pulse, the driver reduces the voltage to .6 to 1.5 volts to hold the injector open. This greatly reduces the power needed to run the injector as well as makes the turn off timing more accurate.

NOTE: Peak and hold injectors will burn out if run for any substantial time on a saturated system.

above quoted from: http://www.pro-flow.com/t-car.html#facts
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Saturated uses a constant voltage to hold the injector open, the Peak/hold injectors use a larger voltage spike to open it and then a lower voltage to hold it open. Typically higher performance cars use the peak/hold style.


You can tell the difference between them by looking at the electrical connector. The peak/hold injectors (low impedance) injectors have a tang centered on the bottom of the connector, the high impedance ones have it offset. Low on the left in the pic, high on the right. There are high flowing saturated injectors available, the older RX-7 turbo has them.
-quoted from Mike W, here http://eclipse.instantip.com/mikew_turbo.htm