MEFI Fuel Injection
MEFI Systems Marine Electronic Fuel Injection
Volvo Penta has used 5 Electronic Control Modules (ECM’s). MEFI 1, MEFI 3, MEFI 4, MEFI 4b and for 1 ½ years, a Ford engine with Ford controls. MEFI 4b is the production module for all 2004’s and 2005’s. MEFI 2 was not used by Volvo Penta. The ECM is the control center of the electronic fuel injected engine. The ECM is nothing more than a computer. A computer consists of a Central Processing Unit (CPU), known as a micro-processor, memory and storage. The micro-processor is the thinking part of the ECM. It is capable of following a predetermined set of commands (programs) and can manipulate data. There are 3 types of memory, Random Access Memory (RAM), Read Only Memory (ROM) and Electronic Erasable Programmable Read Only Memory (EEPROM). RAM is the micro-processors “scratch pad”. The processor uses this to store ever changing sensor values as it makes calculations. Diagnostic Trouble Codes (DTC) are stored here until power is removed (battery disconnected or ECM unplugged). All data is erased from RAM whenever power is removed. ROM is permanent memory, it cannot be erased, this is where the main operating program is stored. ROM does not need power to retain its memory. EEPROM is where the engine calibration is stored, DTCs are stored here from RAM when the power is removed. EEPROM does not need power to retain its memory.
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