DIY MAPPED PROGRAMMABLE IGNITION

For current software, forum and other stuff visit Brent's (the inventor) USA site. MJLJ

Check out the September 04 edition of Retro Cars Magazine for an article on this system!

For info on wiring the connectors and more click here.

About the System

I have always wanted to improve the ignition system of my 1968 spitfire, but found the price of aftermarket products a little prohibitive, so, after a trawl of the internet I came across a DIY ignition system called the Mega Jolt Lite Junior. MJLJ which a programmable control unit for the Ford EDIS (electronic Distributor-less ignition system).

  • The EDIS system was used on most ford 4, 6, and 8 cylinder cars from about 1989 until 1995, which means it can be used with the spitfire, GT6 and v8 motors!

 

  • The MJLJ has a MAP (manifold Absolute Pressure Sensor) which means that the ignition can tell when the engine is under load etc.

 

  • The system is multi spark to improve starting, idling and low rpm emissions.

 

  • The standard coil pack provides a much bigger spark enabling plug gaps to be opened up and improve power a little.

  • Ignition tuning can be carried out in real time ‘on the road’ provided you have a laptop pc with a serial port. There is a live monitor that tells you exactly what RPM, advance and manifold pressure the engine is at. There are 10 ignition points and 10 MAP points that can be programmed at any one of 10 RPM points. There are also 4 programmable dependant RPM switches, tachometer out and shift light out (another RPM dependant switch).

The control unit is scratch built using a circuit board and processor from Brent Picasso, the designer of MJLJ (he has a web site with an order form page). Brent’s site also has a Digikey list of electronic components so all the parts can be easily obtained. The site also has an online forum where Brent and others will answer any build questions you may have. I won’t go into the building of this, but if you are ok with a soldering iron you should not have any problems.

Control Unit with the lid off and in the passenger glove box

Small crank pulley with 36-1 wheel welded on

All other parts, a pickup sensor, 36-1 toothed wheel (it has 35 teeth and a gap where the 36th tooth would go), EDIS module with plug and a coil pack can be sourced from me :-)

 

 I welded the toothed wheel so that the centre of the missing tooth corresponded to TDC of my Triumph pulley (I used a small bottom pulley, but it could be welded to a large bottom pulley in the same fashion).

 

The pickup sensor has to be mounted so that its tip is about 1mm from the toothed wheel and 90° before TDC. The EDIS Module is designed so that if the control module fails the EDIS will default to 10° BDTC to enable the vehicle to ‘limp’ home.

With this in mind the position of the pickup sensor is aligned so that with the engine running and only the EDIS module connected the timing is a solid 10° BDTC at any RPM. I mounted my pickup on an adjustable plate so I could accurately obtain this initial setting. I then removed the pickup and mounting plate so I could weld the plate in its final position (I don’t want vibrations loosening things up and messing up my timing!)

 

Pickup sensor

EDIS module

 

 

 

 

coil pack

Pickup mounted on front engine plate using  a British Leyland sensor mount found on lots of 80's Leyland cars such as metro's

I have my MJLJ located in the passenger glove box for easy access. The EDIS module and coil pack are in the engine bay mounted on home made thick rubber washers to absorb vibrations etc.

 

Conclusion

 After nearly 8000 miles of testing I can say I am delighted with this modification. Idling from my 300° camshaft is super smooth acceleration appears better (I have opened my plugs out to 1.2mm with no problems even at 7500RPM) and fuel consumption has decreased. It is quite a straight forward modification provided you take your time and do you work accurately and carefully.

 

A throttle sensor instead of a MAP sensor can be used, and only requires minor rewiring of the control module.

For more details please visit Brent's Site the USA inventor of this system  http://picasso.org/mjlj/

 

 

 

 

 

New pressed steel trigger wheel is 160mm diameter.

Cast wheel is 120mm diameter.

   

 

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