cafcwest

Does anyone have a good point of information regarding the the choices in EMS and the pro's and con's of each.

Specifically, use of stock CAS, coils, etc.

New to standalone, just looking to be a bit more informed.

thanks

Evil Aviator

That's not possible because one person's pro may be another person's con. Another thing that makes this difficult is that the manufacturers change the stats on their EMS products several times a year, and it would be very difficult to keep up a database without direct input from the manufacturers or sales representatives.

TEC3: Electromotive Coil Packs, 60-2 Wheel only.
Wolf3D: Stock FD coils, FD ignitors on FC coils, or aftermarket coil packs. V4 uses stock CAS, 60-2 wheel optional, V3 uses modified CAS.
Microtech & Haltech: Uses all stock FC or FD components, aftermarket coil packs optional, 60-2 wheel optional on Haltech.

Jeff20B

iTrader: (13)

If you will forgive my meager knowledge, I'll try to add something useful to this discussion...

MegaSquirt: Stock FC leading ignitor and coil or aftermaket ignitors and coils (no trailing support yet), modified CAS (may soon support stock CAS), 36-1 wheel support (60-2 support coming soon or may already be working), much less money (DIY soldering), support forums and excellent documentation, free firmware and tuning software.

cafcwest

Jeff,
I've seen you over there on the MS board and the work you are doing for your 3 rotor. One of my roommates is a big MS guy and wants me to go that way, but doesn't show any desire to provide assistance.
One of my requirements is to get rid of the stock ECU - MS would need to provide ignition as well as fuel. I had considered (and do consider) an MS w/ EDIS setup, but I am not too sure if I have the know-how to setup an ignition table for such a setup. I have no problem losing the split spark, as has been talked about.

To the far left, distributor is not too appealing.

Your thoughts on MS - specifically ignition control.

Jeff20B

iTrader: (13)

I would stay away from EDIS. I think it's a personal thing with me, but the thought of a Ford part on a rotary just sickens me. It also lacks a spark cut rev limiter. It also lacks the ability to set dwell manually (I think) so you're stuck with whatever spark duration the Ford bean counters deemed acceptible for a piston engine. Rotaries like a long duration spark due to their long combustion chamber, so I'm not convinced EDIS is the best thing for the job. EDIS also lacks simultaneous firing (late leading; the piston engine term is wasted spark, which you're probably more familar with) because of the way the unit was meant to spark a 4 cylinder. I'm a real advocate of late leading because it's always improved the ignition capability of my carbed 13Bs. I'm sure it will also help EFI when the mixtures aren't 100% perfect. There is also no leading/trailing split with EDIS if it's set up like renns' 1st gen (one module to two coils per rotor housing, total four per 12A/13B; all four plugs get spark; two at the same time). I don't know if there is any other way to set up EDIS on a rotary than the way renns set his up. He's well-rounded and knows what he's doing, but I can't condone EDIS simply based on this single example—especially when it's so much easier to get ignition control out of the MS without having to buy anything or look through wrecking yards, plus no need to locate, fabricate or install a 36-1 wheel. Lastly if you go with a distributor or EDIS, your engine will sound like a 1st gen (ew yuck, heh). You know, putt putt putt instead of the smoother sound you can only get from a late leading igniton system such as what's found in a stock 2nd or 3rd gen (or DLIDFIS, like what I've got on my carbed engines with distributors). I happen to like the smoother sound and all the other benefits of late leading myself.

I decided if I couldn't get late leading out of the MS, I'd simply use my modded 12A dizzy I built for a carb conversion with future aspirations for a supercharger. The dizzy is only the reluctor and three pickups(VR sensors) and ignitors for direct fire and no cap or rotor, complete with late leading (plus all the inaccuracies and limited adjustability common in distributors). Of course all that's changed with the new wheel decoder software of the MS. Since MSnEDIS came out before the wheel deocer software, it means it's had more time to build up a user base. So far, I think renns is the only rotary EDIS user. By the way, renns' setup was experiencing some high RPM misfires and I don't know if they were ever solved.

Your stock TB (throttle body) has a fast idle air valve which the MS supports. The original MSnS (MegaSquirt and Spark) firmware changed the function of the Fast Idle output to control spark with a distributor (the reluctor with VR sensor/conditioner or Hall sensor would send in one signal, the MS would interpret it, and send out another signal with advance, dwell etc). It's a proven system that's working on many MegaSquirt installs.

We don't want that. What we want is to keep the fast idle functionality and use a different source for ignition triggering, and take advantage of the somewhat more accurate CAS (there is no cam garbage in a rotary, but the gear lash between E-shaft and dizzy drive gear can add up to a little bit of play in the end... I'm not worried about it). The MS can do this with the LED circuits and the MSnS-Extra firmware. The only mods required are to add a simple 1k pull-up resistor to LED D17 (the far left LED on the front of the MS case). The pull-up resistor connects from the +5V side of the adjacent 330 ohm resistor (R23, which is the currect limiting resistor for D17) to the cathode lead of the LED, and then a wire connects from the cathode to one of the X output jumpers (I used X11) which routes it to the main connector at the back of the MS case. The stock FC leading ignitor reacts to a +5V trigger signal, and the pull-up resitor accompishes this. When the LED is off, the coil is charging.

It's nice that there's nothing to buy except for maybe a pack of 1k 1/4 watt or 1/2 watt resistors from Radio Shack or where ever. I used 1/2 watts because I had some laying around, but they're kinda overkill for this application. Anyway, you'll get the famed late leading ignition, your car will still sound like an FC, there is nothing else to buy, and no need for a dizzy or EDIS (and its required 36-1 crank wheel). There is no trailing ignition, as you know, but since it's only good for like 1.5HP (according to a MegaSquirted 12A with a stock dizzy on a dyno), I'm not worried about its loss. What's more, my carbed engines improved quite a bit with late leading, but didn't show a difference when trailing was turned off and on while driving (heh, with the butt dyno). Besides, I simpy can not justifiy the amount of work it would require on my application to make trailing work while retaining late leading. If it's one or the other, I'll always choose late leading over trailing.

Oh, I forgot to mention what exactly is modified in the CAS. All you have to do is pop out the shaft and remove two teeth exactly 180° apart on the 24 tooth wheel. This creates a 12-1 wheel because the shaft spins half eccentric speed. Then you need to either build a VR signal conditioner circuit, or possibly remove even more teeth and go to Auto Zone and buy a PR100 GM HEI ignitor for like $16.99 or so. The ignitor can't handle too many teeth whizzing past it at high RPM, hence to need to reduce the number of teeth on the reluctor wheel. A Mazda 4 cylinder owner had succes when he made a 4-1 wheel out of his 24 toothed wheel in his dizzy (I guess his stock setup was similar to MSnS). Since a two rotor engine has an ignition event every 180°, just like a 4 cylinder, a 4-1 wheel ought to work. Want to be the first to try it on a rotary? Of course you'll need to research a lot more before you start removing any metal, but perhaps this can get you started.

renns

Jeff, some of this Megasquirt-related info needs correction/clarification.

In my application (mostly stock 6-port FC engine), the EDIS ignition setup has shown absolutely zero problems from day one, starting and idling well, and pulling strong right up to 7.5k redline. The problems alluded to were fueling issues related to mapdot accel enrichment experiments I was running at same time as adding ignition control. Intake resonance at certain engine speeds caused decel fuel cut to be triggered. Never change more than one thing at once! Fortunately a datalog revealed the problem and allowed for a easy fix. So, the EDIS does work, but it's not the ideal solution due to lack of programmable timing split. Zero split or fixed split are possible.

The toothed wheel code developed by Phil and James (two eager MS coding guys) will allow decoding of a hacked CAS to fire an FC leading coilpack. The embedded code that supports this is experimental at this time, but will likely result a stable release. Some hardware modification for VR sensor input and coil driver output is needed. This is another solution that gets the car running, but is not ideal as it does not provide any trailing ignition.

A proper Megasquirt-rotary ignition solution providing full native support for the stock CAS and FC coil packs has yet to be developed. There has been some work in that regard, but nothing at the running stage that I'm aware of. The MS-II will likely be the platform for this. Until this is complete, the two above options are available, but both are not ideal.

As for that 'late-leading' theory, I still call it wasted spark. I am baffled as to how you can disregard the trailing spark (10-15 degrees late) as of no benefit, and yet consider firing the wasted spark (180 degrees late!!) as providing many magical benefits. The only dyno testing (not the butt version) of this theory that I'm aware of showed it as having no measurable effect. In any case, if you want wasted spark, you'll need option 2 or three as they both fire FC leading coils.

Jeff20B

iTrader: (13)

Ah, so it was fuel related. That clears that up.

Hey, my new CPU arrived so I can get back to testing (old one was damaged by something I did and NOT related to shoddy design or bad code, or anything like that). I'm nearly at the point where I can construct the wiring harness and fire up my engine. I'll put the wheel decoder to the test.

I suppose my, and others' testing, will help bring the wheel decoder into the foreground. I thought about going with EDIS at one point, but since it couldn't provide late leading, and since I already had a modded dizzy to fall back on, I just waited for the wheel decoder to mature a little more. The wating paid off. I think if I dropped everything else and worked exclusively on the MS project, I could probably have my engine running in a week.

renns, now that the MS-II cat is out of the bag, why not let us know your thoughts and desires for what you'd like to see become available? Seriously, because I don't see a point in MS-II for my application since I don't have an IAC motor or need tighter control of the injectors, as far as I know.

Other than the tiny hole trailing sparks through vs the unshrouded large leading hole, the reason why I disregard trailing ignition is because its influence over the engine's power output is neglidgeable (the NSU Wankel engine doesn't even use a trailing plug, although the position of the single plug in the rotor housing is somewhat higher than a Mazda leading hole). I'm weighing the pros and cons of running trailing with the current MS hardware and finding it rather difficult to justify at this time. While it's true I've never tested stock ignition and late leading side by side on a chassis dyno, the butt dyno noticed a significant difference, and when I did switch trailing on and off while driving, I didn't notice any difference. By the way, the switched trailing was after late leading was installed—I've never switched trailing on and of with stock leading through the cap, but I doubt it would make a noticeable difference as well.

To put it simply, just because a rotor housing has two spark plugs, it doesn't mean they both need the same spark power. Trailing can get away with a bit less voltage due to its shrouded spark area. It's not like a piston engine where each plug requires the same power.

Just a couple corrections about the dyno runs a fellow MSer did, as far as I can remember, the dyno test on the 12A consisted of stock through the cap with stock split, then 0° split, then leading only. The power differences were around 1.5HP, which is within the margin of error for the dyno. There was no testing of a late leading ignition system at that time.

The one guy who did side by side runs of some sort of DLIDFIS setup and stock, and didn't see a difference, is a local guy. I'll get to check out his setup the next time I see his car (it's currently getting a tranny swap). It's an '80 with a modded Nikki carb and I don't know what he used for ignitors and coils. Either way, his engine's total power output is higher than stock, and he should have noticed a difference; especially with a modded Nikki (carbs benefit more from ignition improvements as their air fuel mixtures typically are rarely perfect).

My friend's REPU has a supercharger and bad side and apex seals (it's got lots of blowby, and will get a rebuilt S5 T2 engine soon). His noticeable power output didn't improve either, but he does have an O2 sensor hooked to a guage. The guage used to move around wildly on the rich side of stoich. After late leading, it's totally steady (he thought I had unplugged it, hehe).

Everybody else who's hooked up some form of a late leading ignition system has always noticed something of an improvemet. They're usually quite happy they took the time to hook it up. It's improved every one of my early rotaries with carbs.

Magic, lol. It does change the exhaust note of the engine, so it's obviously burning some fuel, which otherwise would have gone wasted out the tail pipe, to produce this sound (the smoother FC sound, which I described above). If it's a choice between trailing with whatever split or a direct fired late leading ignition system, trailing will get the boot every time. I'll get to a dyno some day, but until then, I'll keep on touting the benefits of all late leading ignition systems.

Wasted spark is a piston engine term. Simultaneously firing is the correct rotary term for FC and FD leading ignition systems. Late leading is a term I coined due to a need for describing the ignition of single and multirotor engines over 2 which fire 0° and 180° sparks.