Ignition Control Options

[MarioVelotta]

So your new to EFI and want to know the difference between ignition options. I took a little time to scope some output channels to help you get a grip on what the different meanings are and how they will effect you.

The first one is a "Single Coil". Pretty straight forward. You are still using a distributor and firing a single coil. Note all of these are done at 3000rpm and a 3ms of dwell (how long the coil is charged). What we are going to be comparing is the Duty Cycle (DC) of each. With a single coil at only 3000rpm we are charging the coil 30% of the time. This is fine for a low performance stock application. In a performance application you will quickly cut into the coil charging time robbing out output because the coil can't fully charge

Spark Output Single Coil.jpg

Next we move to "Wasted Spark". When moving to wasted spark we now have a coil pack that is capable of firing 2 cylinders at once. Hence the wasted spark, it is fining in an exhaust stoke of the paired cylinder. With this setup you can see how the corresponding outputs are now sharing the load and dropping the DC in half. This allows for a higher RPM and /or longer dwell periods. In 90% of applications this a great choice, the perfect balance of performance and reliability.

Spark Output Single Coil.jpg

After Wasted Spark the next step would be "Wasted COP". Instead of using 2 output channels, we are now using 4. If you are driving dumb coils this would require 4 coil drivers. Wasted COP is the same as Wasted Spark only that we are now driving 4 individual coils. And the looks like this. Alternating between 1+3 and 2+4. This follows the firing order of an Air-Cooled VW 1432. Starting to look cool right? You can see the DC hasn't changed either. Just the amount of outputs. This isn't to common because it's hard to fit coils into a beetle and requires more wiring. On an inline engine this is very common.

Spark Output Wasted COP.jpg

Then we come to the pinnacle, Sequential Ignition. "Coil on Plug" (COP) or "Coil near Plug" (CNP). With Sequential ignition we are using the same amount of drivers as we have cylinders. Each output fires a individual cylinder in the firing order. In this case 1,4,3,2. This cuts the dwell of Wasted Spark in half again! Now we can keep our coils very cool and run at an even greater RPM or charge them long enough to ignite 30+psi of boost pressure. This is for the other 10% that need to have the best and want the most control. You will need a Cam Sync to allow your ECU to run in the correct firing order. This is the most complex to setup and tune.

Spark Output Sequential.jpg

I hope this has helped you! Let me know if you have any questions. And if you are curious, my new ECU will drive all of these coil options.

-Mario

[Max Welton]

Very nice illustration Mario. Nice!

Max

[Chip Birks]

Nice to see you around here a little more

[MarioVelotta]

Very nice illustration Mario. Nice!

Max

Thanks Max!

Nice to see you around here a little more

I have to spend my free time somewhere