on the motronic system as fitted to cavvy sri 130s and the like does it fire the injectors 2 times for every revolution of the engine and just vary the pulse width or does it vary the frequency of the pulses independantly of revs? ie 10 pulses every revolution.
if it fires them 2 times a revolution (like once for every spark from the coil) i have an idea of how to make a kind of piggyback ecu type device to convert the injection to sequential operation. dont take the piss out of my idea yet, just tell me if the number of injector pulses is directly proportional to the engine speed.
i`ll make the box , and if it works i`ll post a how2.
youd probably need a boost valve to run it but.
According to my manual it has semi sequential injection. So pairs of injectors are fired, and it's the pulse width that is controlled. I guess each pair are fired once per crank revolution. Actually I've never really though it through.
well thinking about it logically, if say injector 1 and 2 are firing when only cylinder 1 is accepting the charge. Wont this make fuel piss down into number 2 when the inlet valve isnt open. Doesnt dound like a good system to me.
okay yeah that makes sense considering the firign order is 126.96.36.199, so does it pulse both injectors when 1 is on induction, and then both when 3 is on induction. I suppose that would kinda "prime" cylinder 3 just before its induction stroke, if i could call it that.
yeah, all the jetronic systems fired all 4, motronic m1.5 (2 rows of pins on ecu) fired all four, i`m not sure about 4.1. what is the system on the latest c20ne engines(n reg astra 2.0 convertible) with the air mass meter? i`m having bother with a car with that system. anyway back to the main point, yep the early ones fired all four at the same time, so three burst of fuel would be fired onto a closed valve! not too bright! what i propose to do is fit a kind of signal distributor based on a counter/ divider setup, controlling four transistors driving the four injectors in turn off the original signal, retaining original pulse width(or maybe including additional circuitry to widen it a little) with a reset pulse triggered by an optoelectronic switch in the distributor, so it would reset when no.1 is at tdc and count 4 from there, sending the pulse to a diffrent injector every time til it resets again. obviously you would have to increase fuel pressure and maybe fit higher flow(cream?) injectors to make up for the fact only 1 injector is firing at a time instead of four but i still think it would be more efficient, probably more powerful, no fuel condensing on a closed valve. it would be an easy circuit to make, i could post schematics, or make it at my work and sell it for about £20 to folk on the board (a wee bit more as a "conversion" to the local divvies but...)
As far as I can remember (I’ll have to check my books at home) all (bosch) L and Motronic injection systems are semi-sequential. So two cylinders at a time are given fuel. This is done cause it makes sense. At 3000 rpm the engine makes 50 rotations per second. 1 rotation takes 1/50=0,02 of a second. Two hundreds of a second for 4 strokes. 1 (induction)stroke takes 0,02/4=0,005 of a second. If you only want to inject when the inlet-valve is open, your left with aprox. 80% of the 0,005 (this is at 3000rpm, for 6000rpm the time is divided by 2)
So far too little time to inject all this fuel in one time. They get a problem with the size of the droplets and the fuel pressure has to be (much) higher. When they also inject 360 degrees (crankshaft) later, when inlet-valve is closed the time for injecting fuel is doubled. It gives the fuel some extra time to mix with the air in the manifold. Now they only need one amplifier to direct two injectors, instead of one for every injector.
I don’t think there will be fuel condensing on a valve or the manifold, fuel that gets on the valve or the manifold (if it gets there) will vaporise though the heat of these parts.
The K-jetronic system was a constant injection system, and that didn’t lead to problems, so why would Motronic give problems with fuel condensing?
I don’t think that making it fully sequential will give you more power or economy, if you can make something that will make the opening time of the injectors bigger, won’t the system correct its self?
It’ll think, hey my lambda-sensor says rich mixture so I’ll shorten the injection time.
the motronic on my cavalier mk2 SRi 1.8, 2.0 & 130 all fired their injectors in a bank of 4. i`m going for it, gonna try it out, nothing to lose. how much current does an injector draw? i need to get transistors large enough to drive them. got the counter made already. will use a sensor from an hp laserjet printer in the dizzy, with a flag at no1 tdc. (obtaining the parts is no problem cos i repair computers/ electronic equiptment all day at my day job)
Checked the book at home and...Oops I was wrong.... Sorry.
The normal motronic “fires” all injectors at the same time every 360-crankshaft degrees. (my book was printed in 1992)
There are also motronic versions that use sequential injection. This gives the engine better throttle response and power/economy. So it is possible to inject all the fuel in the very short time of the induction stroke.
The ecu will try to compensate the rich mixture when there is not a “full throttle” signal.
At full throttle it goes from “closed loop” to an “open loop”, and ignores the lambda sensor.
So, yes you’ll probably get (a bit) more power with your homemade device.
gonna use a cmos decade counter ic with the outputs for 1 t0 4 going to the bases of 4 transistors with tle clk pin getting its signal from the original injector feed. the reset pin will be triggered from a sensor i`m gonna fit in the dizzy at no1 tdc.
the injectors will be controlled by each of the four transistors, which will be conected across the original injector feed. this way the existing frequency and pulsewidth will be retained. to get the extra fuel i will loosen afm spring , whack up fuel pressure and fit cream injectors. mind you if it only fires the injectors once every 360 degrees i`m screwed... will maybe need to try it on an old 18e or something.