Hubert
06-18-2008, 17:30
OK my understanding goes something like this. Really simplified.
The IP is clocked to the crank/cam such that it builds a possible injection event with fuel very similar to a valves timing with cam lobes. The stepper motor advances timing of the cam mechanism (rotor -housing of the pump) according to operating temperature of the motor. This is done because cylinder temperature has a significant affect on penetration rate the flame front penentration of the combustion event into the cylinder.
And the fuel solenoid opens and closes to meter the fuel out to the injectors electronically controlled via the optic sensor and the measured time of the IP to precisely control fuel metering to hold smooth, economical, and clean power. Such that the fuel solenoid metering does have a significant affect on actual timing of the event according to the IP optic sensor timing measure and PCM control. So that if above possible fuel injection event is not called for by operator/PCM then fuel bypasses internal to the pump and is not injected. And or if the PCM measures stable speed of the IP then it adjusts fuel metering accordingly. None of this happens with a mechanical pump.
If this makes sense then this is why I believe fishbite is a conflict of electronic fine tuning of fuel metering vs mechanical capability of the system. Bad electronic signal or mechanical deterioration of the performance of the mechanical aspect of the electric fuel solenoid. Or a combination.
I have read a worn timing chain will degrade drivability performance. Is this because a worn chain would have more backlash and in affect make IP time as measure vary more. In turn the PCM /FSD would actually have to work faster to try and hold steady precise fuel metering????
The IP is clocked to the crank/cam such that it builds a possible injection event with fuel very similar to a valves timing with cam lobes. The stepper motor advances timing of the cam mechanism (rotor -housing of the pump) according to operating temperature of the motor. This is done because cylinder temperature has a significant affect on penetration rate the flame front penentration of the combustion event into the cylinder.
And the fuel solenoid opens and closes to meter the fuel out to the injectors electronically controlled via the optic sensor and the measured time of the IP to precisely control fuel metering to hold smooth, economical, and clean power. Such that the fuel solenoid metering does have a significant affect on actual timing of the event according to the IP optic sensor timing measure and PCM control. So that if above possible fuel injection event is not called for by operator/PCM then fuel bypasses internal to the pump and is not injected. And or if the PCM measures stable speed of the IP then it adjusts fuel metering accordingly. None of this happens with a mechanical pump.
If this makes sense then this is why I believe fishbite is a conflict of electronic fine tuning of fuel metering vs mechanical capability of the system. Bad electronic signal or mechanical deterioration of the performance of the mechanical aspect of the electric fuel solenoid. Or a combination.
I have read a worn timing chain will degrade drivability performance. Is this because a worn chain would have more backlash and in affect make IP time as measure vary more. In turn the PCM /FSD would actually have to work faster to try and hold steady precise fuel metering????