How would fuel be controlled by the ECU with an EDIS ignition system? It seems the ECU would still need a cam sensor to determine which stroke was intake. Or does this not matter?Could it fire each injector twice as often but half as much each time? I am assuming that with a batch fire system, which mine is, all injectors, or at least one bank fire at the same time, so timing is not determined, but the amount would need to be.

Sam

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The ECU sees the tach signal from the EDIS - and it uses manifold pressure, throttle position, temperature, ambient absolute pressure, O2 sensor correction to determine "how much" fuel to inject via your VE setting and fuel maps. As to when the fire the injectors, it simply fires every spark event - or at least that's the default behavior of the Megasquirt.

IF you're doing multiport, you would simply batch fire them all, or pair them up and batch 'em in 3 groups, using the pairings of the wasted spark, perhaps. Since there's no way, unless you devise some kind of distributor or cam driven signal, to know what cylinder is where, you can't do an accurate synchronized sequential fire.

Besides, you can't do sequential anyway, at higher rpm, because you can't get enough fuel, really. Pretty much everyone uses sequential at low speed and at some point changes over to batch fire, to get enough milliseconds of fuel time between each intake event.

At higher speed, air velocity and the short time between events prevents puddling and wetting anyway, so it's not really critical.

If you really want to do sequential, you'll have to keep within the limitations of the MS system, and instead of using EDIS, use the MS driven ignition (you keep the distributor), which uses a sensor system of some kind to know when #1 gets spark and syncs the system. Theoretically, I believe you could also do some precision machined slots in the cam gear, and a sensor in the cover, but that's getting WAY out there.

Either way, sequential fire IS possible, but you're going to have to study the megasquirt manuals and websites for the details. I am not using it and thus haven't paid that much attention. Sorry.

Substitute "every other crank revolution" for "every other stroke," and you'd be more or less correct. Unless you have very much oversized injectors, at full throttle your injector will be open for about a crankshaft revolution and a half at full throttle. Without a cam sensor, the ECU wouldn't know WHICH crank revolution to do this. It can work firing the fuel and spark every crank revolution too though - that would be a batch fire / wasted spark setup.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

Does this mean you can run a batchfire/wasted spark system with only a crank sensor, and no cam sensor?

Sam

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Yup, that's how the system was designed to work.

That's how my EDIS/MS2 combo is running. Wheel on crank pulley feeds the sensor, sensor feeds edis module, edis module feeds rpm signal to MS2, and to complete the loop MS2 tells module the desired timing.

Nice to see someone already doing what I"m working on.

I chose that after much consideration about the coil driver circuit feeding back or introducing noise into the system. It just seemed wise to separate the two and use components known hardened against the noise already. Also, I wanted to get the ignition out of the distributor, since you can't hardly find high quality caps / rotors and stuff anymore. Also, keeping it up out of the way of water / splashing seemed attractive, too. This truck is for offroad use, so it may be subject to

What was your factor?

Also, later on, if your engine is near stock and not turbo, could I get a copy of your fuel / timing / config setup, to get me started faster on mine?

Thanks

My main motivation was getting rid of the distributor. Second, I wouldn't have to mess with dwell the module takes care of that. The less fussing around with tuning I have to do the better. The EDIS module is fairly robust, not much to go wrong with it. The downside - EDIS has a bit more wiring but its fairly simple - mounting the wheel + sensor can get tricky too.

I think I posted my maps here years back. Try searching under my username and the word edis - let me know if you can't find them I'll dig it out somewhere. The tuning isn't really all that well but its plenty fine to drive - I've since put 10's of thousands of miles on it. The only major change since my original EDIS implementation was to switch to custom plug wires and the dodge coil pack instead of the ford one. Engine is "fairly" stock - nothing terribly radical. 1.77/1.44 valves - crappy port/polish job stock cam - 8.0 (or was it 8.5?) compression and dual dutra duals.

PIerre, What version of MS II are you running?
SAm

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Baseboard v3 - I don't remember the software version off hand but I'll look next time I'm in my car.

How hard was it to get the EDIS running and timed?

Sam

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Sorry for the late response. The hardest part was getting the wheel/sensor mounted. Once that was accomplished the rest was almost trivial. Wiring was annoying but doable. Set the options in megatune, input the timing map and voila. It was pretty neat seeing the engine run without a distributor for the first time.

IIRC going from distributor>msd6a>MSII to EDIS>MSII happened in one weekend with the car commuting the next monday. Again, this was after the mounting was figured out.

Thanks Pierre. As you may know, I have not gotten timing control yet out of MS II. There is still some goofy, basic problem that is eluding me (and others). But once I get that going my next option is to go EDIS. I appreciate your input on that.

Sam

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Ordinarily, I'm not one to advise deleting sensors... I've seen too many guys hacking stuff out and then wondering why it doesn't run well. But for any of you considering the Ford system, based on several hundred thousand miles on two different stock 5.0 systems, I can confirm that it is wonderfully smooth and virtually trouble free... except for the EGR valve position sensor which craps out more regularly than all other components put together.

In theory, I like the design of a computer controlling the EGR valve with one circuit, and monitoring the results with another. It's a fabulous way to see if the valve is clogged, as the computer realizes, "Hey, I asked for the valve to close a little, and I don't sense that anything happened." And voila, check engine light.

But when I test with a voltmeter, I see what's actually happening. The position sensor is connected to the wiper of a potentiometer, such that the output should vary smoothly between Vref (+5) and ground as the mechanical position sweeps from one edge to the other. However, when the pot gets dirty, the static shows up as momentary glitches of 0v during the sweep. The computer has apparently not been programmed to recognize those as noise. All attempts to clean are short-lived at best, and the dealer wants big bucks for a new potentiometer. *sigh* Sometimes I go buy one, anyway.

And we wonder why people tend to ignore check engine lights.

I've actually considering adding a small capacitor to the wiper circuit, to introduce an RC time constant of some small fraction of a second. While it might provide an effective switch debouncing, it would draw a current through the pot windings / wiper... which is exactly what causes that contact point to get noisy in the first place.

- Erik

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Lots of early Valiants and Barracudas have crossed my path.
Also a handful of other toys for variety now and then.

Erik,

Nice to see you around. I like your capacitor idea. How is CA treating you?

Lou

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Home of Slant6-powered fun machines since 1988