Jim Blackwood's Experience with EDIS

Jim has kindly allowed me to reproduce his text here:

This system, using the MegaJolt for a controller, which is an offshoot of the MegaSquirt EFI controller is something I've been using for several years now so I'll pass along some of the things I've learned about it. But first I'd like to say that although combining the Ford EDIS module into the same case makes a simple and attractive system, in the process you lose the advantage of easy parts replacement and availability that makes the Ford system so attractive in the first place. I feel that keeping the two separate is a better approach, even though it adds another component and a few more wires.

But having said that I will also say that the Ford module has proven to be remarkably reliable and the need to replace the module is not likely to be a concern. "You pays yer money and you takes yer choices."

The MegaSquirt (MS) controller and the MegaJolt (MJ) can operate with as little as a tachometer input. Better is tachometer and MAP (a vacuum accumulator is advised to dampen fluctuation) but TPS can be used as noted. Additional inputs such as coolant temp (CLT), inlet air temp (IAT),and Knock Sensor (KS) add tunability for warm-up and other conditions, and a barometric sensor (2nd MAP ported to atmosphere) can give dynamic ambient compensation. From that point on more features can be added but may require code modification and circuit design so the curve steepens. The best and simplest balanced installation will use tach, MAP, CLT and IAT and stop there. This is because the vast majority of installations are set up that way and a tremendous amount of testing and design has been done there, and a support system is in place that you can tap into by simply joining an online forum. There you will find downloadable files that give an excellent starting point for your tuning efforts, and plenty of expertise to help you make the right tuning choices.

Three things are of incalculable value in tuning, should you choose to install them. 

They are, in order of importance: 

• Wideband O2 sensor (WB), available from Innovative Motorsports and others at prices from $200 US on up. However this is mostly useful for mixture control rather than timing, so where ignition only is concerned it goes to the bottom of the list. If Carb or injector tuning is also to be done it goes back to the top; 
• Knock sensor, various control/display devices are available, choice of sensor may need some research. All of the V8's and V6's commonly used have the correct sensor available and I would be very surprised if there is not an application of the B series engine that does also. Something like the Super 7 might be a good place to start looking but the Brits would know the most about that. Costs are around $50 US or less for the sensor and the display cost can vary widely, from a few bucks for components to build one on up into the hundreds if you want data logging capabilities. The MS is now capable of handling these duties, but you'll still want a display device, if nothing more than a red LED; 
• Exhaust Gas Temperature gage (EGT), about $160 US, with sender.

With these three devices, you can do a proper job of tuning on the road and feel reasonably confident of the results. If you feel the need to get every possible fraction of available power, then an accelerometer like the G-Tech is very useful, ranging in price from about $30 for an older unit off ebay to the $300 state of the art units.

With this instrumentation you are in the position to get an extremely effective real-world tune, something where even a dyno sometimes misses the mark.

Starting with a basic curve, about 10° of initial or static advance and full advance of maybe 40°, initial, mechanical, and vacuum combined, and splitting the 30° of dynamic advance between mechanical and vacuum as you feel appropriate, probably favoring the mechanical by a few degrees, you can extrapolate the table or map to give smooth transitions and a curve similar to a mechanical/vacuum distributor. Hey, it ain't rocket science. Then go for a drive.

Keep an eye on the KS and check your mixtures for reasonable ratios throughout the operating range, but at the same time watch the EGT and water temp for any indications of excessive heat. If either start to spike, check mixture first for lean conditions and if that's good advance the timing and re-evaluate. (Retarded timing creates heat)

Once the mixture is good you can begin to advance timing based on the indications of your knock sensor, and of course your ears, but be conservative and work your way up gradually. Induce knock at several part throttle areas of the map to establish limits and a general curve, and work your way up once you are satisfied that you have the lower areas well mapped. After you have gotten accustomed to the system and the characteristics of your engine you can begin to work your way up into the higher areas where knock is no longer detectable by ear. *BUT* do not be tempted to fiddle with the mixture while you are mapping the timing! If you do, it will be necessary to back off the timing and start over. Once you have a good timing map you can go back to the mixture and then begin to balance one against the other. Keep in mind that both mixture and advance affect knock and temperatures so don't make any large changes in one without re-evaluating the map for the other in the same operating range, and as you do this keep a close watch on your instrumentation, particularly the EGT.

Finally but perhaps most importantly, do not push your advance or mixture settings to extreme values without first verifying through experienced tuners that those values can be made to work successfully. Doing that and/or disregarding your instrumentation can rapidly destroy an engine.

Incidentally, with very little work the MegaTune (MT) dashboard is capable of displaying all of these outputs and more. It is very good software for the application and is freely downloadable. Also much work has been done with wireless links to the controller. Although I do not know the current state of those developments, it is possible to plug a device into the controller and another into the laptop and dispense with the cord. Either a laptop mount or a trained passenger is extremely helpful. But note I said "Trained". Your buddy isn't going to casually pick it up and be any help the first time out.

Jim