Well, it seems all good things come to an end, but some times those good things turn to even better things. Remember when Harley went to the electronic ignition, we would change them back to points because it was an easier fix to...

file and gap your points on the side of the road rather than rewire the bikes ignition. Some people just don’t like change, you remember the old Shovel vs. Evo thing , and again with the Twin Cam vs. Evo. So where am I going with all of this, CARBORATORS or should I say E.F.I., now I’m not saying the carb is going the way of the dinosaurs but  most, if not all manufacturer’s are feeling the squeeze for lower emissions, more fuel efficient, and dare I say more reliable motorcycles. The V-Rod is a look to the future with a liquid cooled, overhead cam with a shim and bucket design. Will this power plant  make its way into a FLT frame with a larger displacement, anything is possible , the point is change happens and rather than fight it. We‘ll break down the E.F.I. System and try to get an understanding of  the major components and their function in the system.

 Electronic Sequential Port Fuel Injection (ESPFI) is an engine management system that was first used on 2001 and later Softail and 2002 and later Touring models now the Dynas are also E.F.I. With o2 sensors. The following is a list of the components currently used on HD ESPFI systems.

ECM-Electronic Control Module-this is the brain of the system that collects input signals from multiple sensors, makes decisions and sends output signals to deliver fuel and spark to the engine.

CKP- Crank Position Sensor-this sensor provides input signals to the ECM that indicate engine rpm. The ECM also uses these inputs to determine what stroke the engine is in so it can deliver the fuel and spark at the desired time.

MAP-Manifold Absolute Pressure - this sensor provides input signals to the ECM and reacts to intake manifold pressure and ambient barometric pressure. Intake manifold pressure reflects changes in engine speed and load. Ambient barometric pressure reflects changes in atmospheric pressure caused by weather conditions or changes in altitude. The ECM uses the input from this sensor to help calculate how much air is entering the engine.

IAT-Intake Air Temperature- this sensor provides input signals to the ECM as it reacts to the temperature of air entering the engine.

ET-Engine Temperature- this sensor provides input signals to the ECM as it reacts to the engine temperature of the front cylinder head.

TP-Throttle Position- this sensor provides input signals to the ECM as it reacts to throttle shaft rotation.

VSS-Vehicle Speed- this sensor provides input signals to the ECM to indicate if the bike is moving or standing still.

BAS-Bank Angle Sensor- this sensor is located in the turn signal module and it sends a signal to the ECM if the bike leans over more than 45 degrees from vertical. If the ECM gets this signal for more than one second it assumes the bike fell over and it shuts down both the fuel management and ignition circuits.

Ion Sensing System- this system uses ion-sensing technology to detect detonation or engine misfire in either the front or rear cylinder by monitoring the electrical energy at the spark plug following every timed spark. If an abnormal level of energy is detected across 2 or 3 spark firings the ECM responds by retarding spark timing in the problem cylinder as needed to eliminate it.

Fuel Injectors- the fuel injectors are electronic valves that open and close to deliver high-pressure spray of fuel directly at the intake valve. They are controlled by output signals from the ECM to deliver fuel at a precise moment. If more fuel is needed, the ECM will signal the injector to remain open for a longer period of time. The period of time is known as the injector “pulse width” and is measured in milliseconds.

Electronic Fuel Pump- a 12 volt high-pressure fuel pump, (located in the fuel tank) supplies fuel under pressure to the fuel injectors.

Fuel pressure Regulator- a mechanical device that controls fuel pressure to 55-62 PSI by returning excess fuel from the fuel pump back to the fuel tank.

IAC-Idle Air Control- an electronic valve that’s threaded (each rotation is a “step”) and controlled by output signals from the ECM to open and close as needed to allow enough air into the engine for starting and idle operation. The greater the number of IAC steps, the greater the amount of air that enters the engine through the IAC passages . 

There is obviously a lot going on inside the ECM, but as long as all sensors are working properly your EFI system will compensate for all types of climate and temperatures. The old saying applies, “if its not broke, don’t mess with it”. When it does brake, have a cell phone handy because there are no side of the road fixes.