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EDIS Installation Lessons Learned

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I just finished converting to EDIS for my turbo L28 and thought I'd share some lessons learned. There's a lot of information about EDIS out there, but some of the wiring details were unclear to me until I actually got it on the car and tried to start it. This led to further trial and error which I'll hopefully help others avoid.


Disclaimer 1: There are many sources of EDIS components besides what I used as well as methods to wire them up. This is what worked for me - I'm sure there are other ways to approach this that will work equally well.


Disclaimer 2: There are many other threads here and on the Megasquirt sites that discuss the theory of EDIS and provide the basics for the install. You should read those before starting.


Now, on to the the Lessons Learned:


1) The easiest VR sensor to find and remove at the JY was from a mid 90's Ford Escort or Mercury Tracer with 1.9L. Find one where the passenger side front tire is already removed and take the plastic fender shield off. It's much easier to get to the sensor that way than from the top.


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2) The Ford Explorer EDIS controller from 4.0L V6 is mounted up front to the left of the radiator when facing the truck. It's not on the fender as some others have written, at least not on any of the trucks I looked at.


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3) Chrysler mid 90's V6 3.5L has a coil pack with a flat bottom making it easier to mount than the Ford. I've read that some of their minivans do as well. I took the spark plug wires to get it up and running as my old distributor wires wouldn't fit its terminals. Hint: take the 3 short ones from 2 cars as you'll likely find the long ones too long.


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4) Leave the device that's attached to pin 3 of the EDIS controller attached. It's a filter for the SAW signal. You may as well use it - Ford thought it important enough to include it.


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5) Make sure the JY checkout person knows the controller goes with the coil pack and doesn't think it's an ECU. It was much cheaper that way.


6) I picked up 2 VR sensors and while they looked the same, the mounting holes on one had to be drilled out whereas the other was a closer fit. You might want to pick up 2 anyway as I'll guess that's the most likely part to fail and my JY didn't charge for it - I guess they considered it was part of the EDIS parts.


7) I never found a spec for how close the VR sensor needed to be to the toothed wheel, but in the end I settled on a roughly 1 mm gap. Closer is better so long as it doesn't touch.


8) Make sure you connect power to something that is live with +12V while cranking. Even though I knew this, I STILL goofed it up the first time and wasted time troubleshooting.


9) Revisit the rev limiter and boost limit settings on your ECU. If they are relying on cutting spark, they won't be effective anymore since EDIS has a limp-home mode which defaults to 10 degrees advance when it doesn't get any signal. You need to change to cutting fuel.


10) If you have a 74-78 tach, you'll need to use this simple diode circuit to get the tach to work. Don't bother with modifying Megasquirt - the factory tach didn't respond for me. I found it easiest to wire the diodes at the splices to the controller connector, but you could also do it at the splices to the coil pack connector. FYI, Digikey is a fast and cheap source for the diodes. I don't know if this would work with a 71-73 current-triggered tach since I didn't try it, although I don't see why it wouldn't work. I'll just add that it's not hard to swap a later 74-78 in place of it.


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11) The polarity of the VR sensor matters. Its wires are blue and grey as are the two wires on the controller. You would think that these should match, BUT THEY DON'T! Connect blue to grey, and grey to blue.


12) The coil pack connector has a power lead and 3 thinner leads, 1 for each coil. Connect the black one to the yellow/black wire on the controller, the red to the yellow/white, and white to the yellow/red. Again, it's tempting to connect the matching colors, but then you'll have to ignore the markings on the coil pack for which coil fires for which plugs.


13) The three coils are labeled as 2-5, 1-4 and 3-6. The firing order of the coils is preset by the controller and is

1st: 1-4

2nd: 2-5

3rd: 3-6

and then the cycle repeats. Use this to determine how to attach the plug wires. Remember, the L6 firing order is 1-5-3-6-2-4. For a given coil, it does not matter which of the two posts is attached to each plug as long as the firing order is correct. Remember, EDIS is a form of wasted spark meaning that both plugs are fired at the same time but only one cylinder has air/fuel and hence generates power.


12) The connector for the coil pack has a several inch long device on the power lead. This is a capacitor which helps reduce electrical noise. On the other end there is the green power wire, and also a black one. Connect the black to ground so the capacitor can do its thing. Alternatively, you may find a stand-alone capacitor on one of the donor vehicles. I went this route simply because it was a cleaner install.


13) You should use shielded 2 conductor wire between the controller and the VR sensor. Attach the shield ONLY at the controller. Same goes for the PIP and SAW wires to Megasquirt (or whichever ECU you use). Again, connect the shield at the controller, not at MS.


14) Be very careful with your wiring and go slowly. I would recommend soldering the VR sensor and PIP and SAW connections and then shrink wrap them. It's also a good idea to solder the diodes for the tach circuit as solid wires can work loose in a crimp connector over time. For the rest, crimp connections are fine. Then cable tie the wires into harnesses and make sure they don't flop around.


Lastly, this project took A LOT more time than I had expected. Perhaps it was a few other "while I'm at its" that crept in, but in any event, make sure you budget enough time to do it right. You don't want to be on the side of the road troubleshooting your hurried wiring.


Edit: I should have added up top that I used Derek's EDIS kit which includes the 36-1 wheel and VR sensor mounting hardware. You can learn more about it here.

Edited by Zmanco

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