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Aug 24th, 2023
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Joined: Feb 2014
Posts: 368 Likes: 1
Learner Plates Off!
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Learner Plates Off!
Joined: Feb 2014
Posts: 368 Likes: 1 |
Forgetting for a moment that we are speaking of Morgan three wheelers...... A normal EFI system has a pump that will deliver more volume of fuel then the motor could ever use. Included in the EFI system is a pressure regulator whose job it is to turn the pump on and off to maintain whatever line pressure is deemed appropriate by the manufacturer. Demand on the system (more fuel, less fuel) is then handled by the ECU varying the amount of time the injector is open. The ECU figures out the time by the fuel map in its memory and sensor input.
The fuel pressure has to stay stable throughout the rpm range for the system to work properly. All the components are more or less "tuned" to work together as a system.
The ECU has a certain amount of latitude built into it which is why the M3W posts fault codes saying the injector maps are out of limits when the pump goes bad and line pressure drops.
Modern EFI is truly a marvel when compared to mechanical fuel injection and carburetors.
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Joined: Mar 2013
Posts: 1,015 Likes: 1
Has a lot to Say!
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Has a lot to Say!
Joined: Mar 2013
Posts: 1,015 Likes: 1 |
Forgetting for a moment that we are speaking of Morgan three wheelers...... A normal EFI system has a pump that will deliver more volume of fuel then the motor could ever use. Included in the EFI system is a pressure regulator whose job it is to turn the pump on and off to maintain whatever line pressure is deemed appropriate by the manufacturer. Demand on the system (more fuel, less fuel) is then handled by the ECU varying the amount of time the injector is open. The ECU figures out the time by the fuel map in its memory and sensor input.
The fuel pressure has to stay stable throughout the rpm range for the system to work properly. All the components are more or less "tuned" to work together as a system.
The ECU has a certain amount of latitude built into it which is why the M3W posts fault codes saying the injector maps are out of limits when the pump goes bad and line pressure drops.
Modern EFI is truly a marvel when compared to mechanical fuel injection and carburetors. Nicely put Sir. Most EFI runs the injectors to a max of about 80-85% duty-cycle I think, meaning that there's a little headroom left to increase fuel flow if the ECU calls for it (depending on the demand signals coming to it from the various sensors around the place). That's also why turning up the fuel pressure is a popular trick when tuning a car, as more fuel squirts in when the injectors open for their pre-programmed intervals. Somewhat easier than setting up a pair of 40DCOE's with a box of jets, a screwdriver and that length of hose....!
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Joined: Jan 2015
Posts: 238 Likes: 3
L - Learner Plates On
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L - Learner Plates On
Joined: Jan 2015
Posts: 238 Likes: 3 |
The higher pressure might mean more fuel squirts in for a given injector open pulse but the lambda sensor will sense the richer mixture and will edit the overlay map to reduce the pulse time, it's a closed loop. There is a base map and an overlay map, which gets edited and combined on the fly. As the ecu is locked it's not possible to either merge the maps or change the Air-to-fuel (AFR) ratio. The good news is they are wide band lambda sensors so if you junk the ecu you can have some fun
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