1 VR with 2 flying magnets 180 apart too complex? Really?

[yellow-fever]

Hello all.
I'm truely amazed at all the crazy wheel configurations that can be decoded, my hats off to the people brilliant enough to figure that stuff out, but I can't help wondering if the challenge of getting the next crazy wheel configuration code to work has over shadowed a need for the most simple potentially boring sounding code that could get a massive number of engines running off Megasquirt. It's a simple twin cyl 2 stroke with 2 flying magnets and 1 vr sensor. It is a wasted spark even fire twin firing every 180 of crank revolution or everytime it triggers the 2 magnets set 180 apart from each another. Tooth logger signal looks perfect but with basic trigger setting it reads 2x RPM due to the 2 magnet triggers per 360. I have tried every different toothed wheel setting I could think of or others recommended and the only way to get an rpm signal was with basic trigger or trigger return. Maybe an extra setting to populate when you select basic trigger that is for tooth count, or a way to cut the RPM calculation in half like you can for tach output would work perfect. A simple CDI has been able to do this decoding since the 70s at least and all the major snowmobile manufacturers have used this type of trigger since the 80s and most still do today. I have found no real practical or cost effective way to add a different wheel due to the way the clutch mounts on one end of the crank with a non keyed taper and the starter recoil rope assembly on the other end. I noticed "skidoo ptec" is a wheel choice in the latest code, but it's a totally different more complex wheel due to the electronic reverse that runs the engine backwards. How exactly do new wheel codes get created? Compared to the crazy wheels it can read, this one looks like a piece of cake? Maybe someone can explain to me why it's not? It may be scaring people away from trying out a Microsquirt on thier snowmobiles and or snowmobile engine powered what ever? Power to weight on 2 stroke snowmobile engines are incredible. All the new 800cc twins put out 150 to 160 horsepower with little light compact 2 strokes. Any and all input is greatly appreciate.
Thanks

-Dan

[muythaibxr]

Can you post the non-working msqs?

[racingmini_mtl]

I haven't looked at the code but there is definitely a bug when using a 2-cylinder 2 stroke even fire engine with a basic trigger. It does show twice the RPM and won't allow 2 squirts alternating.

Jean

[yellow-fever]

Ill get the one MSQ with basic trigger working at 2x speed and a couple more using toothed wheel that do not work hopefully tonight if I get a minute, unless there are other wheel settings preferred to try? I think that 2 squirts alternating is not possible with just 2 magnets 180 off each other because it does not know if its cyl 1 or 2 that is being fired with no second reference sensor for cyl id or at least a 3-1 wheel. If I can get it working simultaneous, it will be 2 squirts per cyl per rev and that would work fine. The wheel code needs to start calculating trigger angle after each of the 2 trigger events separate and also know that there are 2 trigger events spaced evenly at 180 for each rev so the RPM will read correct vs 2x RPM that would cause all kinds of timing error if spark was tried. If it knew how to decode 2 trigger events per 360 to get the rpm correct I could still get it to work simultaneous using 1 ign output running 1 wasted spark coil to feed 2 cylinders and have the 2 injectors simultaneous off 1 of the 2 injector drivers. There has got to be a way to add this code using a simple simultaneous setup that would run these engines just fine?
Thanks for all your time and ill try to post some MSQ later.

[racingmini_mtl]

2 squirts alternating should be possible because there are 2 ignition events per cycle. That's all that is needed so the fact that this generates an error message in one indication that there is a bug. The other indication is the doubling of the RPM which is likely related because that acts as if there were only one ignition event per cycle.

Jean

[jsmcortina]

[racingmini_mtl]

I know I'm not the OP but the default msq with just a few changes shows the issue. Simply changing to 2 cylinders, 2 injectors, 2 stroke and basic trigger causes the error message. Then changing to 1 squirt sim enables it to run but at twice the RPM. Attached is that last msq.

Jean

[jsmcortina]

I checked the code and compared MS3. The same code is commented out in MS3 with a note "does this make any sense". The MS2 code looks to be handling the 2-stroke, 2-cyl case as if it were "big bang" where both cylinders fire together. I'm not sure that makes sense.

James

[racingmini_mtl]

I don't think it makes sense for a 2 stroke engine. You can deal with that setup by setting it up as a single cylinder. You can't do anything for the 180 degree 2 stroke twin as it is now.

Jean

[racingmini_mtl]

You can't do anything for the 180 degree 2 stroke twin as it is now.

Actually, I should correct that. You could set it up as a 4 cylinder 4 stroke with basic trigger and 4 squirts alternating. That will be the same as a 2 cylinder 2 stroke with 2 squirts alternating and it will give the correct RPM.

Jean

[yellow-fever]

racingmini_mtl, that is the exact same thing I tried first off after going from the bench to the engine, 2 cyl, 2 injectors, 2 stroke, 2 squirts and got a configuration error with basic, and when I changed it to 1 squirt, no configuration error but it's at 2x speed. jsmcortina, the "big bang" with two cyl firing together is how the factory does it even with the 180 firing order, I think that is considered 2 cyl wasted spark? It would work just fine with 2 sparks and 2 injections per 360 and with a wheel with just 2 magnets spaced 180 apart and 1 vr, it would have to squirt simultaneous and spark simultaneous because it doesn't have a way to tell it it's cyl 1 magnet or cyl 2 magnet. Do you still need my MSQ given its so easy to duplicate? If so I'll head over to the garage and get one. If it just had a way to set the number of trigger events per 360 to 2x vs 1x it would work. Thanks for the replies!

[yellow-fever]

I'm going to try that after supper tonight and post back, I didn't see your last reply before my last post, I still don't understand how that will correct the rpm with 2 magnets per 360, but I'll try anything at this point
Thanks again!

[yellow-fever]

RPM reads correct set to 4 cyl, 4 stroke, 4 squirt alternating. I did not understand the way megasquirt calculates, and the code not working correct for 2 stroke 2 cyl 2 squirts did not make my understanding any better. I was extremely confused to say the least. I now realize that basic trigger mode is looking for at least 1 tooth or trigger event per cyl. I was trying to separate the megasquirt calculations of rpm count and cylinder count when they are one calculation in basic trigger mode as shown by the correct rpm now showing on a 2 stroke 2 cyl with 2 triggers set as a 4 stroke 4 cyl. Now that I have a correct reading, the only problem is it reads correct all the way to 5400 rpm and then goes crazy until it drops back down below 5400. I have put 2 tees into the stock VR sensor wires into VR1 on the microsquirt so I'm not sure if that has something to do with it, but the engine revs past 5400 correct, but rpm goes crazy above that. Would the VR polarity cause that kind of issue or just trigger angle errors with good rpm? Its getting late so Ill play around some more tomorrow evening. Thanks

[ol boy]

There are software noise filters on the vr input if you have them turned on.

On the 2 cylinder 2 stoke issue.. All the twin 2 stroke I play with fire both holes at the same time and only swing a single magnet. The ignition system is a twin output so it fires both holes at the same time from a single ign output. I set them all up as single cylinder engines.

There is the DA100I which is an inline version of the DA100 twin and it swings a single magnet but uses 2 pickups to drive a pair of single ignition coils. Each hole fires 180 degrees from each other. I have yet to put efi of this engine but it does have the same timing issue as the OP. The DA200 4 cylinder is in the same situation.

[yellow-fever]

I think my MS2 has adjustable filters, but never needed to touch them, but this is a microsquirt with a different vr circuit than MS2 I think? I know the latest code has a single magnet with dual vr trigger called twin trigger mode. Sounds exactly like what your DA100l has and looks like it would work great for you as long as the code for twin trigger works?

[ol boy]

The only issue with all the RC Airplane engines is everyone hand starts the engines by flippong the prop. You get one flip which starts against the compression stroke. The current fix is using trigger return and a bipolar hall effect. N magnet at 60 BTDC and a S at TDC. I need a twin trigger return set up.... or some other hardware fix. Idk...

[yellow-fever]

Ah ha, you don't get enough of a revolution to initiate a spark. Hmmmm. I was worried about that with my recoil so I turned skip pulses down to 1 and luckily it's a low compression turbo build so you can get a good pull on it. With any luck it will be ok? I'm going to pull a tooth log with the plug caps off to see how many pulses I can get.

[yellow-fever]

Thinking about alternating vs simultaneous with the setup I am testing. 2 stroke twin as a 4 stroke 4 cyl is a little confusing. If im looking at it correct, alternating would only work correct as long as it started counting the cyl 1 magnet first, it would be in synch with injector 1 firing for cyl 1. If it were to catch the magnet for cyl 2 first it would start that as cyl 1 and the injector synch would be 180 off? I have modified the bottom box in a few screen shots to try to explain better by replacing the cylinder count as well as deleting a few boxes to try to represent what Im trying to explain. If I understand this correct, with no way to tell cyl 1 form cyl 2 it would be a 50/50 shot of it started and synched on cyl 1 or cyl 2. Im thinking the only way for this setup to work correct with no way to tell cyl 1 from 2, would be simultaneous. Im thinking simultaneous will give me two injection events per 360 per injector channel and that would work ok. If I had at the very min a 4/1 wheel it could do alternating fine because it would know cyl 1 form 2. Am I out in left field here? Again! LOL
Thanks

-Dan

[ol boy]

Thats why on FB i was saying just add the 3rd magnet and do a 4-1. The injection cycles would alway be aligned with the right cylinder. I think you could get away with firing both inj at the same time.

[yellow-fever]

I hear you on the adding a third magnet, but like said before with the size of the magnet, a way to attach it and finding a way to ballance it, will all be an issue. 4 stroke, 4 cyl 4 squirts simultaneous is the way im going to try to get it to work unless something changes before then. I really appreciate all the repiles and hope Im not being too much of a pain in the neck?
Thanks again!

-Dan