Two Cylinder (2cv)

General Megajolt Questions and Answers

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randcook
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Joined: Mon Aug 14, 2006 12:42 pm

Two Cylinder (2cv)

Post by randcook »

Hi,

Any ideas or reasons why Megajolt/EDIS woild NOT work on a 2cyl set???

Peter

4600cc
Posts: 0
Joined: Sun Jul 11, 2004 1:48 am

I don't see why it wouldn't.

Post by 4600cc »

I don't see why it wouldn't. You'd take an EDIS-4 and two separate coils, connect output for coil 1/3 to one coil and output for coil 2/4 to the other coil. That should give spark, now whether the timing of this spark will be suitable for your engine is something else..

Gilesy998
Posts: 144
Joined: Tue May 16, 2006 4:35 pm
Location: Liverpoool, UK

A 4-cylinder wasted spark

Post by Gilesy998 »

A 4-cylinder wasted spark system should be ideal to run your motor. The RPM readout on the PC will be twice what the car's actually running, but you'll still be able to manipluate the map. Go on, be a pioneer! Just remember to insulate the two unused coil connectiins.
Gilesy998
1980 Leyland Mini 1000. Stage one tuned.
10" wheels. 4-pot brakes. MJLJ V3 ignition controller.

4600cc
Posts: 0
Joined: Sun Jul 11, 2004 1:48 am

What's the top RPM of your 2

Post by 4600cc »

What's the top RPM of your 2 cylinder engine? If it's more than 5000 perhaps firmware have to be modified, not a big deal though.

MartinM
Posts: 433
Joined: Sat Aug 27, 2005 12:08 pm

Modifying the firmware IS a

Post by MartinM »

Modifying the firmware IS a big deal to mere mortals who..
... may not understand how the MJLJ firmware works in general
... may not be familiar with the assembler language used
... may not know which parts of the firmware (eg code only, data tables only, or both) need changing
... may not know exactly what needs changing and whether there are any side effects of making those changes
... may not have access to the appropriate Motorola development kit software ...
... ...and may not have knowledge of setting it up on a PC or using it
... may not have the ability to reprogram the new firmware into the processor
... may not have access to a test bed that isn't a real engine to test it with

If none of these apply, then go ahead and modify the firmware - and let us know how you get on ;-)

PS All these most definitely apply to me, maybe except the first

bhwm
Posts: 4
Joined: Fri May 12, 2006 1:34 pm
Location: Leicestershire, UK

Double the RPM?

Post by bhwm »

Are you sure the MJLJ would see double the actual engine RPM? I don't see why two missing cylinders would make any difference to the crank sensor, EDIS PIP signal or MJLJ. Maybe I am missing something, but I think it should work with no changes required.

brentp
Site Admin
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Joined: Wed Jan 24, 2007 6:36 am

The easiest way approach

Post by brentp »

The easiest way approach this:

1. Get the EDIS-4 module working on it's own on your 2-cylinder- run it at the default 10 degrees BTDC. See how well it runs.
2. If it runs well enough, then add the MJLJ control- you'll have to manually compensate for any RPM errors
3. If it's set and forget- then stop: you're done!
4. If you really want accurate RPM readings someone might be kind and make the appropriate changes.


just $0.02 from a mere mortal. :)
Brent Picasso
CEO and Founder, Autosport Labs
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randcook
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Joined: Mon Aug 14, 2006 12:42 pm

Citroen 2CV

Post by randcook »

Hi All,
For a start I am pleasantly suprised at the feedback.
Thanks all.

My tuppence worth.

1.The 2CV has a double ended coil wih NO distributer, so I assume it is a wasted spark it is standard form.
2.The big problem is the sensor wheel, as front pully has no (woodruff) keyway to locate trigger wheel to a fixed position.
3.Propose to fit trigger between crank and flywheel but space is very limited, may need to machine a mm from flywheel?
4.Static timing is set at 8deg BTDC,
5.Can the static timing be changed in the MJL parameters.
6.RPM I believe is derived from the trigger wheel so I assume:) is will be correct.
7.Max RPM is 6000rpm? (as no Rev Counter fitted)

Oliver Sedlacek
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Location: The Chalfonts
Contact:

Easy peasy

Post by Oliver Sedlacek »

The standard 2CV ignition is wasted spark anyway. The engine is half of a 4 cylinder engine, and only needs one coil. Use the EDIS-4 and just connect the 1/4 coil. There should be no changes at all for the firmware, and the RPM values should be correct.

4600cc
Posts: 0
Joined: Sun Jul 11, 2004 1:48 am

RE #1: Waste spark fires

Post by 4600cc »

RE #1: Waste spark fires two cylinders at a time, you only have two cylinders, thus it can not be a waste spark. What it could be is two coils in one package. Remember that you need two coils, you'd then connect them each to output for cyl 1/3 and 2/4.

RE #5: Static timing is old distributor days lingo, it refers to timing before it starts being altered via RPM and VACUUM. Once you get digital ignition in, there is no such thing as static timing. Timing will be taken from cells, MJL has 100 cells, 10x10 table, it looks at present RPM and VACUUM and decides which cell to use. If you run EDIS-4 only (without MJL) then your ignition will run at static 10 BTDC and timing will not be altered.


You need to try to make that thing rev past 10,000 rpm!!!!!

JamesC
Posts: 6
Joined: Thu Jun 17, 2004 7:42 am

Alex - of course it can be

Post by JamesC »

Alex - of course it can be wasted spark - it just means it fires on the exhaust stroke.
Triumph Spitfire Mk3 1969
Triumph 2000 Mk1 1969

4600cc
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Joined: Sun Jul 11, 2004 1:48 am

That's MSD. :D

Post by 4600cc »

That's MSD. :D

MartinM
Posts: 433
Joined: Sat Aug 27, 2005 12:08 pm

OK, I'll take the

Post by MartinM »

OK, I'll take the bait....

It's not MSD (as in Multiple Spark Discharge) at all - that's completely different. Use Google..... :D

JamesC
Posts: 6
Joined: Thu Jun 17, 2004 7:42 am

"Examples of engines using

Post by JamesC »

"Examples of engines using this design include the Buick V6 engine Series I and newer, Harley Davidson V-Twin, BMW Airheads, Citroën 2CV, Mazda B engine and Chrysler V10."

http://www.answers.com/topic/wasted-spark
Triumph Spitfire Mk3 1969
Triumph 2000 Mk1 1969

4600cc
Posts: 0
Joined: Sun Jul 11, 2004 1:48 am

Well, could be anything.

Post by 4600cc »

Well, could be anything. The important thing is that one cylinder will be triggered by cyl 1/3 output, and the other will be triggered by cyl 2/4 output. Thus two coils are needed. In fact, this could easily be a true coil over system if two COP units are used instead of coils and wires.

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