CMF_queazocotal
» CMF Member
Does anyone happen to have these, before I start pulling them off and measuring?
Flow rate curves vs pulse width for stock CG10DE injectors.
- Thread starter CMF_queazocotal
- Start date
CMF_fred
» CMF Memberit was my understanding that the standard injectors are 135cc/min flowrate.
CMF_fred
» CMF Memberalso pulse width controlled by the ecu.....
CMF_queazocotal
» CMF MemberThanks!
I don't suppose you know the dead time before they start to produce any fuel.
I assume it's a bit more than 1.5ms?
I don't suppose you know the dead time before they start to produce any fuel.
I assume it's a bit more than 1.5ms?
CMF_fred
» CMF Member
CMF_queazocotal
» CMF MemberI'm trying to compute, from injector pulse widths, the exact amount of fuel used moment by moment.
To compare (for example) fuel economy at slightly different tyre pressures, make nice graphs of fuel consumption per gear at various engine load conditions, road conditions, ...
Anyway - the base figure should let me make some realistic guesses, combined with measured fuel economy over a large fraction of a tank.
To compare (for example) fuel economy at slightly different tyre pressures, make nice graphs of fuel consumption per gear at various engine load conditions, road conditions, ...
Anyway - the base figure should let me make some realistic guesses, combined with measured fuel economy over a large fraction of a tank.
CMF_fred
» CMF Memberthe flow rate is measured when it is at its maximum..ie 135cc/min the ecu duty cycles the injector depending how much full is used..ie at idle it might be 7% at full throttle it mught be 85%... you can buy digital multimeters that measure duty cycle.. i think i saw usb data loggers somewhere too.
CMF_queazocotal
» CMF MemberI know - I've hooked an injector up to the mic input of a laptop, so I have a decent measurement of pulse width.
The problem arises in converting it to a fuel flow.
The injector initially is closed, for the first 1-2ms or so.
Then it gradually opens to full, over the next millisecond or two, and then starts delivering fuel at the nominal rate.
Soon after the electricity is cut off, it again gradually closes. (well, if gradually can be used in the context of things happening in milliseconds).
Ideally, to work out the fuel flow from the pulsewidth, you'd have this graph.
But, just the flowrate lets reasonable guesses to be made.
The problem arises in converting it to a fuel flow.
The injector initially is closed, for the first 1-2ms or so.
Then it gradually opens to full, over the next millisecond or two, and then starts delivering fuel at the nominal rate.
Soon after the electricity is cut off, it again gradually closes. (well, if gradually can be used in the context of things happening in milliseconds).
Ideally, to work out the fuel flow from the pulsewidth, you'd have this graph.
But, just the flowrate lets reasonable guesses to be made.
CMF_fred
» CMF Memberso, need to find out pulse width for each percentage duty cycle and compare it with throttle position? surely, there must be a formulae on the web somewhere?
that would have to be a rainy sunday afternoon in the back shed job, for sure!
that would have to be a rainy sunday afternoon in the back shed job, for sure!
CMF_Yom
» CMF MemberWhen I had the consult computer hooked up I logged TPS, RPM and Injector duty cycle.
Basically i put together a very dodgey way of getting the best fuel economy possible.
Seems to work as I can squeeze stupid mileage out of my fuel without driving around like a snail.
Don't have of the information though. Left it all on the computer which I returned. Poop.
Basically i put together a very dodgey way of getting the best fuel economy possible.
Seems to work as I can squeeze stupid mileage out of my fuel without driving around like a snail.
Don't have of the information though. Left it all on the computer which I returned. Poop.
CMF_Yom
» CMF MemberOh basically all i did was sit there with the numbers and figure out where the optimal RPM/TPS position was (function of the gearing) to give the lowest possible injector duty cycle reading.
Sees that injector duty cycle between 3000rpm and 4000rpm isnt much different - it is more related to the gear you're in and where the throttle is.
My idea now is to always have the right gear at all times, and to use as minimal throttle input as possible. Light compression braking also improves fuel consumption dramatically when on hilly roads.
Sees that injector duty cycle between 3000rpm and 4000rpm isnt much different - it is more related to the gear you're in and where the throttle is.
My idea now is to always have the right gear at all times, and to use as minimal throttle input as possible. Light compression braking also improves fuel consumption dramatically when on hilly roads.
CMF_evade
» CMF MemberYeah ECU cuts fuel when decelerating..way to go on hills
CMF_queazocotal
» CMF MemberI've got a log of several journeys, with GPS, and flow rates (well, injector frequency and periods)
Problem is, the GPS has a lag of several seconds, and I don't have gear, or throttle position info, so the data is moderately hard to reduce, I could write something to guess the gear based on RPM/GPS speed, but this is annoying.
I'm going to be putting on wheel tachos, which should make this almost trivial. his got delayed by annoying other problems.
The main aim of the wheel tachos is to warn of tyre deflation, but it'll of course be ideal for other things, including accurate speed measurement.
Problem is, the GPS has a lag of several seconds, and I don't have gear, or throttle position info, so the data is moderately hard to reduce, I could write something to guess the gear based on RPM/GPS speed, but this is annoying.
I'm going to be putting on wheel tachos, which should make this almost trivial. his got delayed by annoying other problems.
The main aim of the wheel tachos is to warn of tyre deflation, but it'll of course be ideal for other things, including accurate speed measurement.
