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Matt's Megajolt guide


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#1 The Matt

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Posted 20 June 2007 - 08:53 PM

OK people, I've had quite a few questions about how to do this whole Megajolt thing, how hard it is, how much it costs etc. So I've written this little bit of information down to try and help a few people. In terms of how easy it is to do, so grap a cuppa and have a read through. If you still have any questions, PM me. If you have any additions to make to this little guide/review I'd be glad to read them.

Enjoy :thumbsup:

Megajolt information (as I see it):
The basic principle of Megajolt is that you can use some second hand components from other makes of car to allow your mini to move away from the existing distributor set up. The other advantage is that you have mappable ignition, which allows you to fine tune the advance/retard characteristics of your ignition system's timing. The system uses a VR pickup sensor, which detects engine revs off a rotating part (in the mini case, the bottom pulley is used, either fitted with a trigger wheel, or machined with some grooves, see FIG. 1 at the bottom of the page), an ignition module, that talks to the ECU, and also a Ford EDIS coil pack (effectively, two little coils joined together), which gives your engine sparks! The ingition system is what's called 'wasted spark'. This means that each plug sparks twice in the four stroke cycle. So you have, induction, compression, *SPARK* power, exhaust *SPARK*. This is a system that's been used on the likes of your average 1.1 Ford Fiesta for years.

Where does it get its signal from?
The VR pickup is a little magnetic sensor, which monitors the position of a set of grooves on (in most cases) the bottom pulley. The pattern used is a 36-1 pattern. This means that there is a tooth every 10 degrees, only there is one missing at 90 degrees before TDC (well, that's true of the EDIS 4 setup). The missing tooth is used to let the ECU know what position the engine is! ;D

What about using Megalot with a normal carb?
The carb basically works in the same way as it would do on a car with a regular distributor. The megajolt/ignition module just needs a vacuum take off for the advance/retard adustment. This helps determine the load on the engine. This is called a MAP setup, or Manifold Absolute Pressure. The engine is trying to suck in air all of the time, the 'throttle' does exactly as it says on the tin, it controls the amount of air the engine is allowed to suck in. If your engine is revving at 5k rpm, but you have your foot off the throttle, there is more of a vacuum in the manifold than if you are driving along a 5k RPM. If you boot the accelerator pedal, then you allow the engine to suck in all of the air it wants (well, kind of) then the vacuum in the inlet manifold is reduced. The ECU and ignition modules review this pressure information and control the ignition timing to suit the engine load and revs. You can also go for the TPS option, which is another way of controlling the same thing.


TPS v MAP
TPS is a throttle position sensor, it mounts on your carb and detects the throttle position (how far down you have got your foot). This then gets fed into the Megajolt ECU, which then works out whether the ignition needs to be advanced or retarded.
Now, I have gone for MAP, which means I need to use the vacuum take off in the carb/manifold. As I am using a non OE carb I had to make mine up from some pneumatic fittings, but most cars will already have a vacuum pipe fitted, so you can just use that!

I believe that TPS is used where manifold pressures may be a problem (lairy cams etc, where manifold readings would be all over the place). In my case, I am using a 286 camshaft and I was told that I'd get away with using a Megajolt with a built in MAP sensor (so all I had to do was plug a vacuum pipe in to it). This sounded good to me as it meant that I didn't have to mount a throttle position sensor onto the Weber. Plenty of people use TPS, but unfortunately I have never set one up, so this guide is kinda based around the MAP set up.

Pic 1
This is a piccy of the vacuum pipework that I am using. It's a bit OTT, but it means that my vacuum reading should hopefuly be an average of the two inlet tracts, rather than just using the one. I've done this because my carb does not have a vacuum take-off! :(
Image029-1.jpg

Sooo, firstly, you need to think about how to mount your kit. I bought the pickup kit from Specialist Components, which was £115. This comes with a mount for the pickup and a special trigger wheel and mount kit, plus a new bolt for the crank pulley. This kit uses a Magnetti Marelli SEN8D sensor. I got one of those (using that part number as a cross reference) from a local motor factors for around £20.

Pic 2
The kit from Specialist Components, a very helpful firm.
A057.jpg

Pic 3
Mounted in the engine bay:
Image031.jpg

Pic 4
Mounted on the semi-built engine:
A083.jpg

Pic 5
Then, you need to buy a MJLJR kit from AlexF2003 (good guy, easy to deal with and also works with minis a lot, which is a great bonus). From him, the kit is about £140 ish, ready built and set up.
A052.jpg

Pic 6
Then, you need a second hand EDIS kit from a ford (I paid £30 off ebay, but you can probably get them a lot cheaper if you are willing to go to a scrapyard and get dirty).
EDIS.jpg

Pic 7
I mounted mine to the inner wing, above the solenoid, like zis (wiring unfinished at this stage: :P
Image032.jpg

Pic 8
I mounted the coil on an upturned mini coil clamp bracket, which I bolted to one of the crankcase breather bolts. Like zis:
Image028.jpg

Pic 9
Lastly, you'll need a dizzy blanking plug from MRA Minis, I paid £6 off ebay for it I think.
Image030-1.jpg

Sooo, once you've got all that. The mount kit is really straight forward. Take the bolt out of the bottom pulley, leave the bottom pulley in place, attach the trigger wheel to the 'top-hat' that sits inside the pulley, replace the old pulley bolt with the special new one. You then attach the pickup mount to the timing case bolts. Take your dizzy out, put the blanking plug in its place (as shown in Pic 9).


Sort out a route for your wiring loom. Sort out where to mount your coil, then pop to halfords and spend £30 on a set of leads that are the right length (lumention hotwires ones) and the kit shown below, which converts normal type leads into the type needed for the Ford coil pack.:

Pic 10
A066.jpg

Pic 11
A071.jpg

Pic 12
The leads need to have this type of end to mate with the ford coil pack:
A070.jpg

Pic 13
Where I mounted my MJ. I put it here so that I can easily plug the laptop in and leave it sitting on the passenger seat, whilst I fettle the ignition maps:
Image021.jpg

Soo, once you've done all of that. You've got the kit fitted. Now you need to mount your Jolt ECU somewhere inside the car. I mounted mine as shown in the above picture (please forgive the shabbiness of the car, it's from where I took the soundproofing off etc and hadn't been tidied up in that photo). You also need to extend your vacuum take off so it's long enough to reach the ignition module (the bit that comes with the EDIS kit). I've got mine mounted on the inner wing, above the starter solenoid, so the original carb-dizzy vacuum hose will reach to there. Now, you've got everything mounted and you need to make your wiring looms. That is OK if you knwo anything about electrics, just a simple bit of soldering, there is loads of info, with diagrams on the picasso.org site (the maker of Megajolt).

Diagram 1
Okies, so here's a rouhg wiring diagram for the EDIS 4 section of the installation. The piccy shows the harness/multiplug side of the connection:
EDIS4HARNESSPLUG.jpg

Diagram 2
Now, here's a view of the MJ connector pin out. This is as if you were looking at the end of the Megajolt:
PINOUT.jpg

Now, you should be somewhere near being able to power her up and let her rip.
The MJLJR has a built in output for a rev limiter, shift light and also for a rev counter. You can download the PC software off the picasso.org site for free, so you can have a look at how the ignition maps work.

Sooo, total cost, around £300ish, level of skill needed, fair-moderate, time, meh, easy in a weekend if you concentrate. Results, dunno yet! Should be good! :D No more starting problems in the damp, mappable ignition, less lumpiness on lairy cams....................

Think that's about it!

 

EDIT (15/11/14): A quick note about spark resistance, I'm informed that you need to either use resistor type plugs, or resistor type plug leads, but can't use both.  So as most modern leads are NOT resistance type ones, it's recommended that you use a resistor type spark plug.  Something like a BPR6ES from NGK would suffice.

FIG 1 shown below:

Attached Files



#2 The Matt

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Posted 22 June 2007 - 08:31 AM

Well, I just finished this thread off (I think) so I moved it out of its temporary store to up here.

Hope it's of some use to people :P

#3 Jimmyarm

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Posted 22 June 2007 - 12:38 PM

Thanks Matt :P

#4 The Matt

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Posted 22 June 2007 - 01:55 PM

Thanks Matt :P


NP, I've got some more stuff to add yet. I want to do some model specific wiring diagrams, but I aint got around to that yet as I haven't had time to check out all of the wiring diagrams in the back of the HBOL yet! :lol: to be honest, from wiring point of view, it's pretty easy.

#5 Ethel

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Posted 22 June 2007 - 02:22 PM

I'd appreciate some info on which Fords are likely donors -just had a nose round my local scrappers 'n found a few likely looking Fiestas

Also spotted some later Fords have the coilpack on the end of the head - better length plug leads and easier to remove would they be useable?

Same question about what seem to be a later version of EDIS with a MAP sensor built in (assume it's for injection ?)..... and Peugeot coil packs (look even better)

I will look into this on the Megajolt sites - but though if anyone knows the answers already. :P

I've also seen 3 other ways of doing the trigger wheel:

Machined crank damper - but the guy who was advertising a service seem to have disappeared.

Lasercut wheels that screw to your pulley - best to lathe the pulley to fit

D-I-Y cut out of sheet steel.

#6 Ethel

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Posted 22 June 2007 - 02:25 PM

Would also be really useful if everyone who gets it set up and running posts their ignition map and engine details so we can build a reference to help us all.

#7 The Matt

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Posted 22 June 2007 - 02:31 PM

I know my mum's got a 1.1 OHV Fiesta (N plate) and that has the EDIS 4 setup. Also, some of them had a rev counter pin out on the multiplug (pin 11 IIRC). Look in the dash of the donor vehicle to find one with a rev counter. :P

I was going to get the pulley CNC machined, but the setup cost for a one-off killed it. The only problem I see with that is that you are machining a balanced component, but loads of people do it and have no problem. For a one-off, I was looking at IRO 50 I think, for 20+ I was looking at like 5 a piece. I was going to buy some to sell on, but didnt have the money to invest. The main problem I see with a machined pulley, is that you then have to mount your VR pickup in an exact location. Using the adjustable one like I have, you can adjust your trigger wheel to suit your VR pickup location.

There is a website called trigger-wheels.com or similar, they sell laser cut trigger wheels for all sorts of applications.

As for the info on the coils, I've never looked at different types, I assume there are different ratings. In terms of how they work, well, it's two coils, they should all serve a similar purpose? I'd also appreciate more information on this.

#8 The Matt

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Posted 22 June 2007 - 02:36 PM

Would also be really useful if everyone who gets it set up and running posts their ignition map and engine details so we can build a reference to help us all.


That's one of the main things I was hoping this thread would achieve. A library of maps with a list of detailed engine specs. People could then pick from the list to get the map closest to their engine spec and then use that as a base map prior to a full setup.

#9 dn89mini

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Posted 22 June 2007 - 03:15 PM

My ignition map is attached. Its from an Emerald K3 and uses TPS, but the shape and values should be fine for conversion to MJ and MAP

Where did you get that T piece for your vacuum hose?

Engine Spec

1275cc
MG Metro Cam
Calver Sports Spec head
10.75 Compression ratio
Emerald K3 ECU using TPS (MAP being added soon for Alpha-N+MAP)
Specialist Components trigger wheel and SEN8D pickup
Ford Dual coil pack (Focus not EDIS)
Jenvey SF45 Dual Injector Throttle Body with 2 x 310cc Bosch injectors


Thanks

Attached Files


Edited by dn89mini, 22 June 2007 - 03:42 PM.


#10 The Matt

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Posted 22 June 2007 - 03:18 PM

Where did you get that T piece for your vacuum hose?


I got it form work (pinched from one of the many pneumatic supplies we have here). Probably available from the likes of RS etc. It's for 6mm ID push fit pneumatic hoses. :P

#11 dn89mini

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Posted 22 June 2007 - 03:25 PM

Pinch me one ;-)

Just a note on my map, the 0 values at 7500 are not 0 degrees advance, I have a rev limit at 6800 so zero's out anything above. Dont copy that if you plan to rev higher and extend the shape of the curve with values around 28-32 dependant on your spec.

#12 The Matt

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Posted 22 June 2007 - 03:31 PM

Pinch me one ;-)


:P

Ummm, could you edit your post with the map in it to include an engine spec please? :lol:

#13 dn89mini

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Posted 22 June 2007 - 03:44 PM

Done

Also RS part number 812-229 should be ok if anyone needs one

#14 The Matt

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Posted 22 June 2007 - 03:51 PM

Cheers matey! :P

#15 The Matt

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Posted 22 June 2007 - 03:53 PM

Oooh, and if a mini doc wants to either move this or close it, feel free to :P

I have no mod powers in here :lol:




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