using a crankshaft position sensor to implement electronic ignition

[Build-A-Burger]

I'm just about to get my Spartan-3E to read an optical sensor mounted next to the harmonic balancor so I can display the engine RPM. Thinking ahead, I would like to someday implement electronic ignition using COP (a coil over each plug) after the computer learns how to read the MAP, O2, TPS, baro and so forth. I would of course, have to have some kind of sensor (hall-effect switch) where the distributor was to tell TDC of piston #1 because the crank sensor would fire on #1 TDC and 180 out. So I'm wondering if reading just one point on the crank as opposed to a missing tooth wheel would be fast enough to change the timing needed for a typical V8 engine.

 

[dick_freebird]

I'm just about to get my Spartan-3E to read an optical sensor mounted next to the harmonic balancor so I can display the engine RPM. Thinking ahead, I would like to someday implement electronic ignition using COP (a coil over each plug) after the computer learns how to read the MAP, O2, TPS, baro and so forth. I would of course, have to have some kind of sensor (hall-effect switch) where the distributor was to tell TDC of piston #1 because the crank sensor would fire on #1 TDC and 180 out. So I'm wondering if reading just one point on the crank as opposed to a missing tooth wheel would be fast enough to change the timing needed for a typical V8 engine.

The modern-ish cars I've worked on have CKP (crankshaft position)
sensors but this gives you two possibilities for trigger, 0 and 180
camshaft degrees from where you want. A camshaft sensor
supplements this to pick which one (camshaft and spark timing
are straight-up related, but can be a bit sloppy if there's timing
chain / timing belt slop).

Aftermarket kits seem to often have only the crank sensor (bolted-
on opto chopper or flying magnet or reluctor).

You might find it easiest to pick up a used MSD (or other) add-on
kit and interpose your project between the trigger and the power
electronics - get the code right, based on proven front and back
ends) and then you can mess with those ends if you like soldering
as much as coding (and maybe be able to swap back and forth
for debug / tweak, have stuff to measure that works, as an
example or "golden unit").

Not sure whether you -need- to have the crank true-up, I think
I've seen references to "wasted spark" that is thrown at the
end of exhaust stroke (the desired spark is at end of compression
stroke, right before TDC) so your crank wheel alone suffices and
electronics, harness, sensor neediness is minimized).