Fuel injector operation
Fuel injector operation
(OP)
How many different methods are there of controlling the fuel injectors?
I am tinkering with building a fuel injection system for a small 2 cyl. engine. I was thinking of using pulse width modulation (pwm) to control the injectors.
Is the the norm, or am I way off in right field here?
I am tinkering with building a fuel injection system for a small 2 cyl. engine. I was thinking of using pulse width modulation (pwm) to control the injectors.
Is the the norm, or am I way off in right field here?





RE: Fuel injector operation
Cheers
Greg Locock
RE: Fuel injector operation
Seems to me that both could be true, as the difference between throttle body vs. multiport, or as neon vs. viper (low end vs. performance cars)
RE: Fuel injector operation
Cheers
Greg Locock
RE: Fuel injector operation
RE: Fuel injector operation
There are many feedback loops in an EEC, except when it is running open loop, when it essentially picks up the table values and uses them
Cheers
Greg Locock
RE: Fuel injector operation
Tim
RE: Fuel injector operation
The main difference (i guess) is that i'm trying to make the system dynamic and do all the calculations on the fly instead of referencing a map. Is this a ridiculous prospect? or should I just accept that I need to use a map.
RE: Fuel injector operation
I think it is a good idea. Anyway, here is what you need:-
1) Mass Air Flow sensor or Temperature+Manifold Absolute Pressure sensor (you have to choose either one)
2) Throttle body (cable or drive by wire) with potentiometer inside
3) Crank sensor with lots of teeth while at the same time having few missing teeth
4) Fuel injectors
5) Distributor or distributorless ignition coil
6) Lambda sensor
With these sensors and actuators combination you can have a pretty good closed loop engine control system. Of course, you can add in knock sensor, outside air pressure, coolant sensor, etc. to get your system more interesting.
Next you should get a programmable ECU and a Modac. If the engine is only for dyno and you really love programming, you can program your pc and buy the module to get all the sensors and actuators connected.
I personally love dynamic system because it gives more freedom in various operating conditions for example desert, rain, alpine, snow, etc. With the map based system, it needs to refer to the mapping and you will have to do a lot of parameter adjustment to adjust it to the operating conditions.
AO
RE: Fuel injector operation
I follow you with all the required sensors. I am curious about the crank sensor. 'lots of teeth, but missing teeth'? Would I not want 2 rings? one with lots of teeth, and another one with only a 1 or two teeth to reference TDC for cyl. 1, or even 1 ring modified to do both jobs.
I already have the processor that i'm going to use, and am slowly drawing control circuits each of the sensors.
RE: Fuel injector operation
Sorry for that, what I meant was the trigger wheel should have a lot of teeth to enable it to detect even the slightest movement. This is very important especially for more accurate operation. It will also enable the start up time to be reduced.
As for the missing teeth, new generation trigger wheel has more than 1 missing teeth to enable the ECU to detect whether the piston is at its top dead center or bottom dead center. This is very important during engine cranking.
If you do not have any missing teeth, you may need camshaft sensor reading to enable the ECU to superimpose the two signal and look for the BDC or TDC.
Anyway, all the best, dont forget to post more question along the way.