7.3 diesel cranking over more than my v-10 is that normal
Yes, it IS normal for a powerstroke diesel to require more revolutions of the motor to fire than for any gasoline engine. Combustion in gasoline engines is stimulated by spark plugs and many gasoline engines will start with little turning of the motor past the position where the ignition timing creates the spark and combustion occurs. Combustion forces the engine to continue rotating and combustion in that and other cylinders becomes a perpetual event. A Powerstroke Diesel engine requires more revolutions and speed of revolutions to create the heat necessary to cause the diesel/air mixture to combust. ALSO, the diesel is injected into the combustion chamber, at high pressure, by the injectors. The injectors are electronically controlled and the Fuel Control Module (computer) (also known as the Injector Control Module or ICM) tells each injector exactly when to open and inject diesel into the combustion chamber, as well as for how many milliseconds it stays open (how much fuel will be delivered). Summary, a powerstroke diesel will only begin the perpetual combustion process when the motor is turning fast enough and the pistons are compressing the volume of the cylinder into the tight space of the combustion chamber rapidly enough to create enough heat for the fuel to ignite and begin creating power to turn the motor without the aid of the starter. IN ADDITION, a Powerstroke will NOT start at all with weak batteries. Not only does the motor need to revolve rapidly in order to start, the injectors require a MINIMUM voltage of MORE THAN 12 volts in order to activate (open). The exact amount of voltage required can be different, depending on the Fuel Control Module (FCM) or "Injector Control Module" (ICM) type that is installed. (Note; terminology for the FCM / ICM tend to depend on who you are talking to, what resource you are reading, etc. They are the same thing.) If batteries are weak, the starter uses enough amps to drag the voltage down and, even though the starter turns the motor fast enough that any gasoline motor would fire right up, the ICM will never send the signal to the injectors for them to activate so, the cylinders never get any fuel and the motor never fires. I hope that helps. Yes, a 7.3L diesel will normally need to turn with the starter for longer than your gasoline fueled V10.
Jun 19, 2014 |
2000 Ford F350 Super Duty Super Cab