The typical configuration is a missing tooth wheel on the crank to give engine speed and identify TDC which allows calculation of each cylinder angle. The cam sensor tells the ECU which part of the cycle the individual cylinder is on since injection and ignition only occur every other crank rotation (every 720 crank degrees or 360 cam degrees). A single wheel on the cam or distributor will do both. Wasted spark ignition ties each pair of cylinders that are 360 crank (180 cam degrees) degrees apart and fires the spark plugs of both on every crank rotation so you are "wasting" one spark event. This allows you to run without identifying individual cylinder phase and obviates the need for a cam sensor. The Ford EDIS ignition system is a common example of wasted spark and is frequently used with MSII in a hybrid fashion.

so if i decide to stick with the wasted spark system can i still use the coil on plug setup without adding a seperate ignition system? which is looks like the ms2x and the ms3x do.

Steve,

Well said! Smart Racing used to do the Distributor modification for this.

Coils vary in whether they have built-in igniters (smart coils) or not (dumb coils). Dumb coils require a 12V high current driver such as on the main circuit board of MS ECU which only comes with 1 default (you can add more). MS3X comes with low current 5V "logic" drivers that are specifically designed for "smart coils" and will need a high current igniter added to allow control of a dumb coil. Even the smart coils vary in their input impedance which defines how much current draw is required. The MS3X on board driver in only capable of 25 milliamps so you may not be able to run 2 coils simultaneously from each output if the coil impedance is too low and current draw exceeds the controllers capacity. This is where adding a "spark box" or external high current drivers helps even with smart coils.

ok so what would i need to do for external high spark drivers? I was wanting to be able to skip the cam drive since i am going with a set of 964 cams that dont have the air pump drive. and was planning on mounting the scavenge pump stright to the cam tower like a euro 930. I think all the cam driven scavenge pums sensors have to use the type with the air pump drive correct me if i am wrong.

Clewett makes a scavenge pump with a built in cam sensor for those with a big enough budget and I think TurboKraft was talking about something along those lines as well. One option is just to go with the tried and true of an EDIS setup. It works really well whether single or twin-plug. The EDIS modules have built in igniters. You do have to decide if you want dumb coils requiring 12V high current control or smart coils needing a 5V low current control.
Here are a couple of threads on the MS3 forum about building spark boxes. I would recommend hanging out on that board and reading the supporting info.

Megasquirt MSEXTRA and MS3EFI support forum • View topic - 4 way external ignition driver

Megasquirt MSEXTRA and MS3EFI support forum • View topic - MS3X Spark Box

Megasquirt MSEXTRA Manual Index

Megasquirt MSEXTRA and MS3EFI support forum • Index page

MegaSquirt-3 Engine Management System

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Thanks i saved them all to my favorites. Glad you told me about the cam timing deal i was 5 minutes away from ordering a crank trigger when i read it. i'll just figure out which way is the least expensinve for what i have to do.

OK i checked out clewetts turbo scavenge pumps they only work on 930 cam shafts. Not 964 cam shafts. So still need to figure out what to do can the ms-2 be used with igniters to do the same thing?

Are you running a 930 scavenge pump off of the left hand cam (roll pin modification)? If not, Clewett makes a Cam sensor adapter kit for sequential which is what I am using. If you don't think you can get a cam signal then my next recommendation would be to go with MS3 and EDIS. I ran 2 EDIS controllers in parallel with MS2 and then MS3 for twinplug control before finally upgrading to MS3X. Not as sexy as COP but very cheap and efficient and the EDIS coils are really strong. This has the advantage of not requiring any major circuit building and my experience has been that the EDIS crank sensor system is better than the VR circuit on the MS board (less finicky).

I've also done a couple of twin plug EDIS turbo motors. They both worked very good. One of them I used Mopar coils. The coil wire ends a standard stuff you can get at most parts stores and the mounting bases are flat and easy to mount. If you have the cam out it fairly easy to fit with a drive stub. It would also be fairly simple to make a spacer for the scavenge pump and fit a geartooth sensor for a cam position sensor.

yes currently i have ssc cams, but i have a set of 964 cams that will use the roll pins to drive the scavenge pump. i have had issues with the seal on the cam boss leaking so I wanted to try the other way. also a set of stock 964 cams is several hundred dollars cheaper than getting 930 cams reground.