MS3X Build - Capacitors

Ask questions about DIY board assembly issues, fault finding and testing. (Covers all Megasquirt versions and board.)

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DaveEFI
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Re: MS3X Build - Capacitors

Post by DaveEFI »

Q16 is somewhat of a throwback. To when it was common to use just one coil and a distributor. It is basically a high current single coil driver.

With your existing EDIS, the EDIS module contains the four high current coil drivers needed for your EDIS wasted spark coils.

MS3X has (up to) 8 low current ignition outputs. To drive your wasted spark coils without the EDIS module, you'll need to add 4 high current drivers. Or change to 'smart' coils (with built in high current drivers), which could be either wasted spark or sequential with the addition of a cam position sensor.

You could use Q16 as is and add the extra high current drivers. But it would make more sense to me to have them all in the same place.
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garrycol
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Re: MS3X Build - Capacitors

Post by garrycol »

Thanks Dave - So I don't need Q16?

And from what you have said, if I do not end up using the EDIS 8 I will need to buy some drivers for the coils. I guess I need to research this as well as I am not keen in buying more coils.

Is there any advantage in going sequential spark over wasted spark? The engine has a cam position sensor on it.

cheers

Garry
billr
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Re: MS3X Build - Capacitors

Post by billr »

I suggest installing the Q16 stuff, just to keep the build "standard" and easily usable in the future for new purposes; either by you or somebody else. It's just a few easy solder connections and having that driver in there won't interfere with other ignition configs, like using the MS3X spark outputs. I don't believe there is any advantage to COP over wasted-spark, except eliminating high-voltage plug wires. That's speaking only about NA engines, maybe a highly-boosted engine would need extreme spark capabilities.
garrycol
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Re: MS3X Build - Capacitors

Post by garrycol »

Thanks for that additional information - its a shame that type of information is not listed in the actual build instructions - on a sentence or two - rather than referencing another section which in turn references another section.

Any way we move forward.

Cheers

Garry
DaveEFI
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Re: MS3X Build - Capacitors

Post by DaveEFI »

garrycol wrote:Thanks Dave - So I don't need Q16?

And from what you have said, if I do not end up using the EDIS 8 I will need to buy some drivers for the coils. I guess I need to research this as well as I am not keen in buying more coils.

Is there any advantage in going sequential spark over wasted spark? The engine has a cam position sensor on it.

cheers

Garry
I'm still using EDIS8 on my RV8. No pressing reason to change it here.
If I were getting rid of the EDIS module, and getting MS to provide the high curent for the coils, I'd likely fit those drivers in a second box and fit that where my EDIS module currently is. Easier to make a good job of that than trying to squeeze four drivers inside the MS case. In which case I'd use the supplied Q16 as one of the four drivers inside that box. But it would be easier to buy a QuadraSpark unit, if you don't like constructing your own.

Not sure if sequential ignition would be any better on a relatively simple low tune engine.
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billr
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Re: MS3X Build - Capacitors

Post by billr »

One advantage for COP is that spark advance can be "trimmed" cylinder-by-cylinder. Again, with no means for extensive (steady-state runs) dyno time, I sure can't benefit from trimming spark.
garrycol
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Re: MS3X Build - Capacitors

Post by garrycol »

I dont think that for a bread and butter low performance vehicle there is not much point in trying to squeeze every last HP out of the engine sorting out individual cylinder spark.

Thanks for the comments.
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Re: MS3X Build - Capacitors

Post by garrycol »

Ok after some time away from the project I have basically completed the project of building the MS3X ECU - tested Ok but some follow on questions.

The engine is a Thor Rover V8 4.6 - so in theory will be sequential injection but batch should be OK. Using EDIS 8 for ignition - this will provide a failsafe for me if the MS3X fails as it is also a gas (LPG) vehicle - so can run OK on default EDIS 8 and gas with no megasquirt. Using the standard RV8 PWM, cam sensor, knock sensors and after market O2 sensor.

1. On completion of the build still got D1, D2, D8 and R12 spare - not on the 3.0 mainboard. R 57 is not on the board and not in my left over parts. Going back over the assembly instructions I am not sure whether these parts should be in or not.

2. On the MS3X card it has a jumper for the Tacho - JP3. Now my Edis 8 works the tacho fine but I guess I need an option in the future to run the tacho from the MS3 - I assume I leave the jumper in place for this

3. JP7 deals with Cam input and not sure whether to leave the jumper on or not. As far as I am aware the cam sensor in my engine is a simple on/off switch - so not sure whether to leave the jumper on as it is at the moment.

4. In section 13.7.1.1 says that before connecting up the MS3X board the VR pots should be set to their initial settings - so is is this the VR pots (R11, R32) on the 3.0 mainboard or the VR pots on the MS3X board? I have went back over the instructions and cannot find anything about setting up the VR pots on the 3.0 mainboard but there is for the Cam for R11 and R32. Given my on/off can sensor not sure if I use the optical sensor or magnetic sensor setting - do the VR pots on the main board need to be set up first.

5. Lastly - I damaged the 3.0 mainboard where Q20 is soldered. As a result I am nor sure the top connector for Q20 is actually electrically connected to the board.
See red arrow spot.
ImageCircuit Board by Garry Collins, on Flickr

The other connectors seem OK - looking at the motherboard from the top as in the pic, there seems to be a connection going to the top connection of Q4. So can I bridge the top connection of Q20 to Q4?

Your thoughts on any of the above would be appreciated.

Thanks

Garry
DaveEFI
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Re: MS3X Build - Capacitors

Post by DaveEFI »

Q4 and Q20 are both part of the low current FIDL circuit. Do you actually need this? It's not much used these days. But the top leg of Q20 (emitter) - as shown in your pic - goes to ground, not to Q4.

D1 & D2 & R12 are part of the opto input. If you are using this input, follow the notes on how it needs to be configured. If you are not using it, no need to build it.

D8 is part of that FIDL circuit. Again, if you're not going to use that, no need to build it.
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garrycol
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Re: MS3X Build - Capacitors

Post by garrycol »

Thanks - what does FIDL mean?

"But the top leg of Q20 (emitter) - as shown in your pic - goes to ground, not to Q4." Just looking at the circuit board - the top of Q20 runs to the top of Q4.
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Re: MS3X Build - Capacitors

Post by kjones6039 »

garrycol wrote:Thanks - what does FIDL mean?
Fast Idle.......

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DaveEFI
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Re: MS3X Build - Capacitors

Post by DaveEFI »

garrycol wrote:Thanks - what does FIDL mean?

"But the top leg of Q20 (emitter) - as shown in your pic - goes to ground, not to Q4." Just looking at the circuit board - the top of Q20 runs to the top of Q4.
I have a bare new V3 PCB here. No connection between the 'top' of Q20 and 'top' of Q4 (top being by your pic) Refer to the schematic.

If your board is partially built, a continuity meter may show a reading via a different route.
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garrycol
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Re: MS3X Build - Capacitors

Post by garrycol »

Thanks to both for you input. Not sure whether I need fast idle or not - I am just following the build instructions - adding components as it indicates. I will make a note and if subsequently needed I will add the components later.

Any thoughts on my point 4 re the VR pots?

Cheers

Garry
billr
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Re: MS3X Build - Capacitors

Post by billr »

All four pots do need to be adjusted, and the instructions for the mainboard ones are certainly in the manual; but the procedure is very similar to the ones on the MS3X.

Adjusting of the mainboard pots (for CKP sensor) and the MS3X pots (for CMP sensor) is completely independent.

For VR sensors the "adjustment" is generally quite simple: turn both pots fully CCW and leave them alone.
DaveEFI
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Re: MS3X Build - Capacitors

Post by DaveEFI »

garrycol wrote:Thanks to both for you input. Not sure whether I need fast idle or not - I am just following the build instructions - adding components as it indicates. I will make a note and if subsequently needed I will add the components later.

Any thoughts on my point 4 re the VR pots?

Cheers

Garry
When building, there are usually choices to be made. On such involves the Fidl circuit - as many need a different higher curent design. So no point in building the standard one if you later have to modify it to the high curent type.

The VR pots allow a big range of sensors to be used. You might have to alter them from testing with a Stim to the actual sensor on the engine.
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garrycol
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Re: MS3X Build - Capacitors

Post by garrycol »

billr wrote:All four pots do need to be adjusted, and the instructions for the mainboard ones are certainly in the manual;
I cannot find them in the build instructions - must be somewhere in one of the other instructions - it would be nice if things were in the one spot.

I will turn the mainboard and MS3X board CCW and go from there.

Thanks

Garry
DaveEFI
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Re: MS3X Build - Capacitors

Post by DaveEFI »

Adjusting pots wouldn't be in the build part of the manual. As this would have to be done with a ready built one too. You need to refer to the ignition section that covers your actual ignition. Same with Fidle. That also depends on the type of fast idle device you intend using.

Because MS can be used with a big variety of things like ignitions systems and so on, it would be impossible to give build instructions just for you. So the individual should spend some time going though the entire manual with reference to how they are going to configure it, and remember where to look for the specifics.
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