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Perfect Power Piggybacks and Stand-ALone ECUs

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Perfect Power Products

The Perfect Solution to a Powerful Engine Management System


XMS Peak and Hold

Model: XMS_PH

The XMS_PH is an injector driver for high current injectors with an impedance of less than 4 ohms. Peak and Hold (PH) drivers are required to drive these injectors in order to reduce the power consumption, which would otherwise heat the injectors, and evaporate the fuel. Actually the fuel starts boiling in the injectors, and gas is injected instead of a liquid, and the engine leans out. This can have disastrous effects.

Features of the Peak and Hold Unit:

  • 4 independent drivers
  • Negative input drive signals with incorporated pull-ups
  • Negative output drive
  • Up to 12A output peak drive
  • Settable peak time
  • Settable hold current
  • Settable Recovery time
  • Three build-in set-ups for slow, medium and fast injectors
  • RS232 communications port (PC software provided)
  • High impedance OFF switch reduces off delay
  • Optional external fuse
  • 2 LED indications
  • Short circuit protected, RED LED shows early output termination
  • Small size
  • To be installed in ambient airflow


The injector is switched on with a very high (up to 12A) peak current. This assures that the injector ‘opens’, which is evident by the ‘plinth’ hitting the full open position (limit). This is normally achieved within 0.7 to 1.2MS. Then the injector current is switched off for a variable recovery time. This allows part of the peak energy to dissipate. Then the injector is operated with a variable PWM current, which reduces the effective current to about 0.8 to 1.5A. This is the holding current, which must be great enough to hold the injector open. Once the input pulse terminates, all the ‘switches’ open, the injector energy dissipates in a high voltage spike, and the injector closes very fast. Thus the injector is opened as fast as possible, and closed as fast as possible, with the minimum of electrical energy, and a minimum of heating. Low impedance injectors (with high flow rates) are meant to be operated with a peak and hold driver.


  • High power engines
  • Low impedance injectors
  • Fast injector operation
  • Gas injection
  • Converts normal injector drive to Peak & Hold
  • Impedance conversion

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