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Okay, so EFI needs a pickup in order to tell the ECU when the engine / crankshaft is at a certain position. Can the original pickup that is part of the diagnostic port be used, or is it there with no function? My guess is it's useless, otherwise folks wouldn't be having to fabricate magnetic pickups on the engine... Thought I'd ask though :) Thanks
A great question that I have wondered about myself but not done any homework on!
The EFI modules need an ignition signal of some type. Whether this is a tach pulse from the gray/white wire off the coil or a VR signal directly out of the distributor doesn't matter, Megasquirt can be jumpered to receive either. In the latter case, a coil driver on board can fire the car's coil in place of the stock ECU (or multiple coils), thus allowing Megasquirt to alter the timing.
To eliminate our distributor altogether would require two pieces of information for Megasquirt to interpret: the position of the crankshaft and the position of the camshaft. This is done with missing teeth on a gear (optic), or as you allude to, some kind of magnetic sensor on a wheel (hall).
On an even fire car, one need only identify when a cylinder is TDC with a sensor or tooth and then mathematically predict when the other cylinders (using % of 360* rotation) need to fire. The Megasquirt doesn't know if the particular cylinder is on its compression or exhaust stroke since the camshaft goes around twice for every crank rotation. Therefore it uses what's called "wasted spark" and since there is a cylinder on the exact opposite stroke, sends the spark to both of them at the same time, ensuring that the one on the power stroke gets lit.
Enter odd fire. The above wasted spark won't work because there is no cylinder that is 180* opposite from the other. That means any timing becomes dependent on knowing not only that the cylinder is TDC, but that it is on its compression not exhaust stroke. So, we must sense both cam and crank position. We can't just set this up once and forget it since every time we shut down the engine the "memory" of the timing is lost. When cranking, the info from the two sensors resets everything.
So, having one sensor on our cars would be insufficient to eliminate our distributor. Wasn't ours on the flywheel? (this would indicate crank position). If so, then adding one on one of our cam shafts would be necessary too. Then the dizzy can come off and you could run coil-on-plugs or coil packs so long as you had a coil per cylinder. Definitely could be a cleaner install and should be a better, more reliable spark since you won't have dizzy losses.
I'm dying to try this one of these days.......
Thanks for the info. The D's sensor was originally aimed at the flywheel and of course there are no teeth missing for optical sensory, my guess would be a magnet installed in the flywheel to indicate TDC? Thing is I'm not sure they actually installed one or not (If not, perhaps I can drill a hole and glue a magnet in it)... I'm running even-fire, it would be much easier to use the magnetic pickup from the original set up than trying to find another way, ya know? My distributor is on the end of the cylinder head - that will be staying put. Thanks again!
It is a lot less work to run EDIS off the crankshaft with a 36-1 trigger wheel. Plus it allows you to have a limp in mode if the system fails.
Could you elaborate a bit on that Josh?Quote:
Originally Posted by DPI JOSH
EDIS is great for even fire applications. ( I think that the OP is dealing with an eagle bottom end)Quote:
Originally Posted by Spittybug
This is our preferred method of premier swaps. (while we will still install an early style distributor driven engine)
This gives you the ability to minipulate the spark curve and run a coil pack(s). EDIS is from basically any ford engine from a few years back and has the awesome ability to provide a base timing limp in of 10 degrees regardless of input. Basically lots can go wrong and the engine will still run.
The integration into megasquirt is simple and heavily documented in the megamanual. I think the biggest plus is removing the distributor system from the engine platform.
I'm actually running a Volvo EFI engine because I have about 2 or 3 of them worth of parts. When I was considering doing this years ago - I have done a lot of research on the EDIS system (and have probably hundreds of pages of print-outs regarding it) and the setups are super cheap, typically through Ebay - but I was feeling out if I could use the pick-up just for "getting it running" sake. I can't remember who it was but some folks have adopted the EDIS into their EFI D engine successfully and offered their experiences with it - I have some of the documentation. Ultimately yes, I would love to be distributor-less and running coil packs and I even have the coil pack (and I even have a Ford now that runs this system for reference). I believe the trigger wheel gets installed on/behind the crank pulley, very easy to do. For the time being, I'd like to get the car running and upgrade as I go.
I was previously attempting to run the Volvo ECU, but have done so much research on the MS system that I'd feel more comfortable running that anyway.
I'm sure I'll have more questions in the future - Thank you for the fast responses and suggestions, I 'preciate it!