Redefining the idea of a clean engine: EDIS for ACVW


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Before – a fairly clean engine with 009 distributor, Bosch blue coil and stock fuel pump

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After – a really clean engine



Late into fall of 2009, Mr. Catbox put an idea into my head that I simply couldn’t ignore.  The idea was to replace the ignition system in my ’66 Beetle as I knew it, with some completely different.  He painted a picture of an ACVW with no distributor, no fuel pump, and an ignition system that could be programmed on-the-fly with a laptop computer.  Certainly this type of system must cost a fortune to purchase, right?  How about less than $300?


Description: C:\Users\thestofans\Desktop\EDIS\Megajolt_system.jpgHe directed me toward some websites and left me to my imagination.  After a week or two of research, I was convinced.  I was going to install a Ford EDIS system on my 1835cc air-cooled VW motor.  What is EDIS?  EDIS is electronic distributor-less ignition system.  Without getting into too much technical detail around how EDIS works, you need to know this (the technical detail is here:

1.       A trigger wheel is attached to the crankshaft – it is missing a tooth which is used to index the crank position.

2.       A variable reluctance sensor (VR sensor) is positioned about 2mm above the trigger wheel and produces a signal as the engine rotates which is read by the EDIS control module.

3.       The EDIS control module receives a signal from the VR sensor, and lacking any additional input, produces a trigger to the coil pack at 10 degrees advance (limp-home mode).

The great thing about the Ford EDIS system is that they made a version for 4, 6 and 8 cylinder engines – AND it can be adapted to just about any motor.  Since Ford made millions of these cars – obtaining the parts needed to install you own EDIS system begins with a trip to the salvage yard, EBay, or CraigsList.  You should be able to get all of the EDIS parts for $70 or less.  You will need the following components off a 1990-1999 Ford Escort:

1.       The coil pack and spark plug wires (located right of center on top of the motor).

2.       The EDIS module (located on the right side when facing motor)

3.       The VR sensor (left side behind the serpentine belt pulley)

4.       The trigger wheel – attached to the engine side of the crankshaft pulley (take the pulley too).

5.       As much of the wiring harness as possible – the more wire you can get – the better.

If you just want to get everything you need (with some guarantee that it will work), you can buy everything from Boost Engineering.

Now you’ve gone out and either bought them off E-Bay or pulled them yourself out of the yard and now have a pile of Ford parts in your garage – what do you do now?  If you are paranoid like me and have access to a “backup” motor – you will want to start figuring out how to mount the trigger wheel to the crankshaft pulley and where to place the VR sensor.  This is a very important step and will directly impact how successful the project will be. 

Placement of the trigger wheel on the crank is dependent on where you are going to locate the VR sensor.  I decided to place my VR sensor at the centerline of the case.  I ended up building about 5 different VR sensor mounting brackets before settling on the one I’m using now.  There are tons of different ideas around the VR sensor mount.  The bottom line is that the sensor needs to be securely mounted about 2-3mm above the trigger wheel for best signal quality.  I suggest building a bracket that has some room for adjustment.  Since I was removing the stock fuel pump, I used the studs from the fuel pump to attach the bracket to the engine.  Another thing to keep in mind when mounting the VR sensor is clearance around the fan belt. 

Description: C:\Users\thestofans\Desktop\EDIS\DSCN3625.JPGOnce you’ve decided on the position of the VR sensor – the trigger wheel needs to be mounted to the crank pulley.  If you have money to burn – you might find a machinist that will mount the trigger wheel to your crank and make it perfectly balanced.  If you don’t have money to burn – you can get really close by using the serpentine belt pulley off the Escort, a metric bushing that will fit in the hole of the Escort pulley and an extra long crankshaft pulley bolt (DIP sells them).  The bushing will snugly fit into the serpentine pulley hole and the pulley bolt will fit perfectly in the bushing.  Simply bolt the whole thing up to the engine, position the missing tooth at 90 degrees, and then carefully drill 6 holes through the edge of the trigger wheel and into the pulley.  Buy some nice stainless machine screws and Loctight and bolt it all together.  Note – in this picture TDC is pointing down.  When at TDC the missing tooth would be located at 90 degrees (as opposed to 270 degrees as shown). Once the trigger wheel is securely mounted – the serpentine belt pulley can be carefully removed.


Description: C:\Users\thestofans\Desktop\EDIS\EDIS_Module_harness.pngIt is now time to handle the wiring.  You will need to buy about 15 feet of security wire from Home Depot.  This wire has two conductors, a foil shield and a ground wire.  You will also need enough general purpose wire to connect EDIS module (which I recommend locating under the back seat) to the coil pack.  When complete, you will have the security wire and three wires going from the engine compartment to the back seat.  Here is a suggestion for good signals – solder your wires.  When connecting the VR sensor to the security wire – SOLDER YOUR WIRES!  Make sure ALL of the ground wires are soldered together.  Under the back seat find a spot to use as a central grounding point.  Clean the area down to bare metal, drill and tap a hole for a ground point.  Do not skimp on the ground point.

Back to the paranoid bit – you can hook the EDIS system up to an engine and wire everything up and make your engine run, but it will be stuck at 10 degrees advance until you have a way to control the advance.  This means you will need to purchase one additional item to make all this work - a MegaJolt Lite Jr. (MJLJ) module.  The MJLJ is what make it all work together.  By hooking the PIP and SAW inputs from the EDIS module to the MJLJ controller you can control the advance that is being supplied to the engine.  Detailed info on how to hook it up is here:  Depending on how you order it – this module will cost between $90 and $180.  AutoSportLabs builds and sells the modules (or DIY kits) on their website. (or you could buy it with all of the EDIS parts from BoostEngineering)

Back to the brain dump… the MJLJ can be bought setup to use either a MAP sensor (manifold pressure) or TPS (throttle position sensor).  I bought mine with the MAP sensor.  With dual Kadrons – I do not get a stable enough manifold pressure for the MAP sensor to be much benefit.  I may switch over to TPS in the future.  Worst case scenario is that I can set the MJLJ timing curves to match any mechanical advance distributor I want.  For example, I have mine setup to mimic the timing curves for either the 010 or 019 distributors.  I can switch between 010 and 019 curves by flipping a switch.  I have also wired up a shift light that can be programmed for whatever RPM I want.  The MJLJ also allows me to hook up a temperature sensor and allow it to advance or retard timing based on temperature (not implemented yet).  Now for the real geeks – you may wonder about the built in timing retard for #3 on VW distributors – I do not have a way to do this yet.  I will monitor #3 for overheating and take steps to Description: C:\Users\thestofans\Desktop\EDIS\IMG_5349.jpgaddress the issue if it becomes a problem.

Once you’ve removed the fuel pump and distributor you’ll need to cover the holes with something else.  Discount Import Parts (and most VW shops) sell a fuel pump block off.  As for the distributor hole – I opted to cut the top of an old distributor and use the stock clamp to hold it in place.  I had Mr. Catbox paint an eyeball on the remaining distributor shaft with the hope of being able to see when I had #1 cylinder lined up (for adjusting valves).  The pupil of the eye spins when the motor is running. 

Performance has been outstanding.  I can honestly say that my engine is running smoother than ever.  Throttle response is great, idle is solid, and it drives like a new car.  Fuel economy needs some work, but that may be due to my heavy foot and the fact that it runs a little rich.


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This shows the VR sensor on the final mounting bracket.  I ended up buying 3 inch 90 degree brackets from Home Depot to hold the sensor.

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I trimmed the mounting holes off the VR sensor and opted to clamp it to the bracket instead.  The copper piece is half of a grounding clamp.

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Locating the coil pack is a challenge.  The clearance behind a doghouse fan shroud is about 4 inches.  The coil pack with wires attached is a quarter inch shy of 4 inches.


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Side view of the mounting bracket.  Note the clearance between the fan belt.

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Another view of the mounting bracket.


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Early attempt to mount trigger wheel to pulley.  Note the addition holes from mistakes made.

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One thing I did discover is that the trigger wheel needs to be offset from the pulley in order for the VR sensor to get a clean signal.

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This shows the trigger wheel with the serpentine belt pulley (after I cut the belt part off) being used to align the trigger wheel to the pulley.  The center piece can be pressed out afterwards.

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This shows the coil pack and EDIS module (lower right) on the test engine.  I started the engine on the stand to verify the system worked.