The DIYAutoTune.com Peak and Hold Injector Driver Board drives up to eight peak and hold injectors. It can work with all MegaSquirt products, other standalone engine management, and OEM ECUs. The board takes an input siganl from an ECU intended to run saturated injectors, and uses its internal circuitry to regulate the current flowing through the injectors. When an injector opens, the current flowing through it will increase until it reaches the peak limit of 4 amps. At this point, the Peak and Hold Injector Driver Board will go into hold mode, limiting the current to 1 amp until the signal controlling the injector is turned off. If the battery voltage is too low to allow 4A to be reached, the full battery voltage will be applied for a period of about 3.9ms after which the driver will go to the hold phase and provide 1A.
Using the Peak and Hold Injector Driver Board provides faster and more consistent injector opening times than driving low impedance injectors through resistors. It also provides better cold start performance than resistors since the injectors get full battery voltage to open them; when using injector resistors, the injectors may not even open if the battery voltage drops too far.
Peak and Hold Injector Driver Boards are available in solder it yourself kit form, or ready to run.