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 Post subject: Megajolt Ignition How To
PostPosted: Thu Aug 20, 2009 10:45 pm 
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Location: Wodonga - Vic/NSW border
This is nothing new for Ausmini, back in 2005 Cody (aka GT1310) set up a Megajolt on his car, and KLAS in Germany did the same. Pristic, Benjamin and Boostedmini have it on their turbos, and there are probably a few others too. Ben (aka 92) has some experience with it - making trigger wheels and sensor brackets as a kit...

here's Cody's original thread, where he gave quite a lot of detail on how it all works

http://www.ausmini.com/forums/viewtopic ... is&start=0

and a bit more detail here, including a picture of Ben's trigger wheel

http://www.ausmini.com/forums/viewtopic ... lt&start=0

The bit I had the most trouble with was actually identifying the bits and pieces - it's referred to as a "Megajolt", but the actual name is "Megajolt Lite Jr." and it comes from Autosport Labs - they have 3 websites, www.autosportlabs.com is their online store where you buy the stuff, www.autosportlabs.org is the forum where you can chat, and download other people's ignition maps, and www.autosportlabs.net is the technical details, software etc. The Megajolt can either be bought assembled, or as a kit. You may be able to solder a bit, but unless you know what "SMD" components are, and how to solder them, I suggest you buy it pre-assembled.

For a normally aspirated engine, MAP sensing is the best, all you do is hook up a vacuum line to the manifold - DO NOT hook it up to the vacuum advance line on the carburettor that the vacuum advance distributor connects to - different thing - no good for megajolts

so buy these bits:
the assembled megajolt w/ map sensor
programming cable - best to just get one from here (you also need a USB-Serial adapter - don't buy a Belkin one, they're rubbish
case mounting flanges - I wish I'd bought some!

The Megajolt is 'driven' by the Ford EDIS system ('Electronic Distributorless Ignition System') which handles the firing the coil, and getting the signal from the crankshaft trigger wheel. The Megajolt talks to the EDIS, and does the thinking for it - basically the EDIS tells the megajolt what RPM the engine is doing, and the Megajolt looks at the RPM, along with an engine vacuum reading, and tells the EDIS when to fire the sparks.

here's what you need from a Ford - I believe the only Fords we have had in Australia that have the required parts are is the first model Mondeo, around 1993, and it needs to be an automatic, as the manual had the EDIS stuff built into the engine computer.

I paid $110 for the required parts, my dad paid $50, and I had a quote from a wreckers in Melbourne for $150 - so there's your rough price range. Pay as little as possible, don't pay more than $150

I've taken Cody's picture, and cut out what we don't need - from left to right you've got the VR (variable reluctance) sensor, which looks at the trigger wheel on the crankshaft, then you've got the EDIS module, then you've got the coil pack. EDIT: See below, don't bother with the ford coilpack, it's ugly, and needs stupid sparkplug lead connectors

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You've gotta make sure that you get the connectors that go into each bit - they're all specific to the part they plug into. Also, the VR sensor doesn't need to be off the Mondeo, Falcons and some others have the same thing.

The coil pack has massive connector clips on the coil ends of the leads, which are a real pain, the leads are too long, and the plug ends don't suit our plugs. You can get custom leads made up, but that's expensive, I tried removing the clips from the leads with some success, but then pristic said he'd just jammed the normal leads on the coil pack - I tried it, worked well - no worries - they haven't come off, or look like they're coming close to it. There are pictures of them later on.

The hardest part is making/buying a trigger wheel, as I said above, Ben aka 92 makes them and sells them. He graciously gave me the design for his wheel, which I made a CAD model of and gave to my laser cutter, who spat me out a couple.

I was all set to machine it myself, but the boss at work said the machinist needed something to do so gave it to him along with my drawing - came back to me with about 5mm of runout, wobbled all over the place :roll: I gave it to a mate who is a toolmaker who fixed it for me, he needed to clean up the harmonic balancer a little as the casting is rough where the face of the trigger wheel mounts. He gave it back to me and said "it's got about half a thou of runout, but it's as good as I can get it" - that'll do :lol:

The trigger wheel has 36 teeth (one missing), so there's a signal sent to the EDIS every 10 degrees. The missing tooth is there to tell the EDIS where top dead centre of #1 intake stroke occurs. The missing tooth passes the sensor 90 degrees (9 teeth) before TDC. In the photos below, #1 is at TDC, the tooth with the yellow paint on it is the TDC tooth. I had the trigger wheel cut with all 36 teeth intact, so that I could remove the one I didn't want after I'd determined the position of the sensor.

here's my trigger wheel as it came from the laser cutter

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I can have more trigger wheels cut out for about $30, but that's just a flat cutout shape, it needs still machining, so if you don't have access to a lathe or someone good with one, then maybe talk to Ben.

here's the pulley mounted to the harmonic balancer. The two screws are screwed into the existing threads in the harmonic balancer, nice and easy.

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here's the pulley and where it sits with the radiator

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here's how I did the sensor bracket, others have mounted it off the timing cover, but I thought I'd do it off the radiator mount, it doesn't make any difference, but I figured this way would keep it out of the way a bit better. Notice that the mounting holes are slotted so there is some adjustment in where the sensor is positioned.

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here's the sensor and bracket installed

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and in the engine bay all messy
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The clearance between the sensor and the trigger wheel isn't too critical - anywhere between 0.75 and 1.5mm, the most important part is that the leading edge of the TDC tooth is in line with the sensor at true TDC. There is adjustment in the software to allow for any error, but get it as close as you can.
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Once the trigger wheel and sensor are mounted, think about mounting the coil pack. I bent up this bracket with some nutserts and welded a bit of angle to it, then mounted it on the alternator bracket, rather nifty I thought... does need a little more bracing underneath it

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(note the 1 3/8" welsh plug in the distributor drive hole :D)

The EDIS unit, and the Megajolt are easy to install, just bung them up under the dashboard on the passenger side. I made a little loom to go between them with a connector that joins them both to the rest of the car and out to the coil pack. The installation guide for the megajolt specifies the wires to use, the key thing the megajolt people say is to use screened cable for the VR sensor wiring - I used this wire from Jaycar. I ran my VR sensor wire through the loom hole behind the wiper motor and down behind the dash pad. No need to drill any holes. In fact, I didn't drill a single hole for the whole installation - not one

There is a minor difference in the Mondeo EDIS module to the one specified in the Megajolt manual - there is no earthing wire for the VR sensor sheild in the connector, so it's OK to leave it off.

Here are the bits where I've put them under the dash, they're tucked away on the passenger side, as close as practical to the VR sensor while still being out of the elements

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the hose going into the megajolt is the vacuum, I have twin SU's, and already have a vacuum port for each carb in the spacers between the manifold and the carbs, so I put a bit of hose on each one of those, and joined them about 8" away from the manifold with a T piece. I figured, and my guru agreed, that it'd smooth out the intake pulses if I did that instead of take it from the manifold - theory is good, but no idea if it really makes a difference. Do it any way you like, but just don't do it from the carb's dizzy vacuum port as that port shuts at idle, which will mess up the ignition map.

SO once you've got all the hardware installed, and you've wired it up as per the Megajolt installation instructions, it's time to start the car.

Get the megajolt software from the autosport website and load it up on your computer, configure the COM port and connect it to the megajolt with your USB - serial adapter, and the cable you bought with the megajolt. When you turn on the ignition, start the software and it ought to connect to the megajolt, and will show the default screen, the advance, the load (vacuum) and rpm

If you've got everything connected up, the engine should just start first go, the 'base map' that is in the Megajolt's memory when it's first used is pretty good, and certainly won't do any damage. Infact, I spent a couple of weeks driving around on the base map before I realised that the changes I was making weren't being committed!

As for ignition maps, the autosportlabs.org forum has several for minis, at least 2 of them have been uploaded by KLAS, who is a user on here. I tried the one he did for his MPi engine, and one that (I think) he made from the published advance curve of an Aldon Yellow distributor. My car goes better on the Aldon one than the MPi one, but the difference is minimal. The priority is to get the car on a dyno to optimise the ignition advance for all RPM bands under all load conditions

Here's what the UI looks like, the table in the main part of the screen is the ignition advance map. While the engine is running, the ignition advance changes depending on the current load and RPM, the cell highlighted (only when it's running) is the current setting. The big green number at the bottom ("Ignition Advance") is the actual advance - the advance is interpolated between the values in the table, IE where the RPM goes up in 500rpm steps, if you're at 4250rpm, but the load is still 60KPa, then the advance will be somewhere around 48 degrees etc.

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Up and down is the load, the more you put your foot down, the higher the load (low load is at the top of the table, high load is at the bottom). Across is the RPM, pretty obvious... as the engine goes faster, the RPM goes up. For instance, cruising along on a flat bit of road at 4000rpm, my load is about 60KPa, so the engine is running at about 47 degrees advance, when you put your foot down, the load increases to over 100KPa, the advance drops to 33 and away you go :)

total cost for me was:
Mondeo parts $110
Megajolt kit ~$140
Trigger wheel $30
VR sensor cable, various connectors ~$20


Last edited by simon k on Mon Aug 24, 2009 2:53 pm, edited 10 times in total.

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 Post subject:
PostPosted: Mon Aug 24, 2009 2:55 pm 
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Andrew, aka ahf001 has added this very helpful tip on using a Hyundai Excel X3 coil pack. The Excel coil may be better as it's easier to mount, and uses standard spark plug leads

afh001 wrote:
for the Excel coil, the +12v wire is on one side of the connector, middle is cyl 1&4 coil, other side is cyl 3&2, I drew a little diagram to explain it all, as the wiring changes colour either side of the connector for the coil, so thought it may get a little confusing...

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Here's a pic of the 2 coils side by side, the Excel one isn't much smaller, but a better suited shape for what I want to do, and it's a lot easier/cheaper to find new or used. The metal bracket can be removed (I'm using it as is at the moment)
Image

Andrew


continuing on, here's a picture of an Excel coil installed, this particular one came off a single cam engine, the one pictured above is off a twin cam. They are identical, and will both suit.

Image


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PostPosted: Tue Nov 15, 2016 10:05 am 
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Yay For Hay!
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Joined: Wed Sep 08, 2004 9:27 pm
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Location: Wodonga - Vic/NSW border
handy!

nicholasatkins wrote:
its pretty easy using the installation guide just follow the numbers. had a quick look at mine on the edis plug

no.1 - green/white is the pip signal to mega jolt (shielded cable)
no.2 - red / yellow is the saw signal to mega jolt (shielded cable)
no.5 - green to - on crank sensor (shielded cable)
no.6 - blue to + on crank sensor (shielded cable)
no.7 - cable shields + ground
no.8 - +12v on edis
no.9 - Green/black to ground
no.10 - green/yellow to no.1 brown/geen on coil pack
no.12 - brown/red to no.3 brown/blue on coil pack

no.2 on coil pack purple/black needs a +12v
the mega jolt also needs a +12v and ground

make sure you use shielded cable for the signal wires to the crank sensor and the mega jolt and earth the sheath and all +12v are switched via ignition.

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