Originally Posted by Impuls
You posted what you think the output is. Which turns out is wrong. It's inline 100 ohms.-
So, what's your point again?
It's not wrong--add in a 100ohm resistor inline and it's how it works. The 5v output comes directly from the CPU and it just happens to have an inline resistor on the output. It does
pull-down to ground with a 100K resistor and also happens to have a flyback circuit built in back to 5v.
The inline resistor is just current limiting. A 100ohm resistor on a 5V output is limiting the current to .05A (5v/.05A = 100r). The output will still be 5v.
I was pointing out the difference between the DIYPNP, MSPNP2 & MS3x vs. the most MS1 and MSPNP1 units is that former is normally low and the latter is normally high, but both ultimately output a digital 5v signal.
When I suggested the MS in question had a 1K resistor, I was referring to a MSPNP1 built on the v3.57 board that has a built-in 1K resistor pull-up. If you look here on page 7
, you can clearly see R58 and R60 for yourself.
One needs to be very specific when asking questions because there are many varieties of MS out there.
I posted the schematic of the 1K pull-up on the v3.57 board. That was the resistor I was talking about. The MSPNP1 was built using the v3.57 mainboard, the MSPNP2 uses the micosquirt module. There is a big difference between the two, especially in regards to the spark output.
The MS, in all its varieties, has no issues firing the stock coils, or toyota coils, or almost any other ignition setup people have used (like GM coils). The only ignition setup that people seem to be having issue with is this FAB setup. Please note: I'm not saying anything bad about the product; just saying.
I suggested changing the 1K resistor because back in 06 or so, when we were building MS1 units, we started switch from a 1K pull-up to a 100-300ohm pull-up to 5v because it was suggested it would help provide a cleaner spark signal. It's been so long I don't quite remember the reasoning, but it could be part of the problem here. Here's a thread that I talked about it back in 2009.
I also remember someone having issues with the ms expander board and trying to run wasted spark off it or something. I'd have to go back and find it. Could be somewhat related; like it couldn't fire two coils from one output. I just can't quite remember and I'd have to go back and find it. I think they changed the firmware after that to give the option for wasted COP so each coil fired from its own circuit but in a wasted firing order.
But like others have suggested, the "power" of the signal from the ECU shouldn't matter. It's not directly responsible for providing power to the coils. All it's doing is toggling from 0v to 5v and when it does, the coil knows when it should release its own charge to the coil. It just needs to see that switch from low to high, it doesn't matter how many amps is passing through, because it's not using it. That's why it's called a trigger. Like when firing a gun, it doesn't matter how hard, or lightly, you pull the trigger, all that matters is that you pull it.
Keep in mind: I am not an electrical engineer, engineer, or electrical. some might describe me as magical, but I also describe electricity as black magic.
Now don't ever question me again.
Edit: here's a thread where it was discussed how to convert the MS output to trigger 12v safely, and more about current limiting resistors
. I think it also speaks to as why people should listen to Joe P on this subject. And post #17 talks about the 1K to 100ohm pull-up switcheroo. I'm still leaning in this direction.