I'm not sure it's only related to Microsquirt. The important part is when you give power to the coils I think.
However on the Microsquirt, once the high current drivers are removed and you set "Going High" for spark output, those two outputs will be Low when the ignition comes on (they are no longer inverted by the drivers), so the coils aren't triggered.
The spark output through the LED circuit is inverted because it goes through an IC that switches ground, which is why you need the pullup resistors. The code knows that the circuit is inverted, so it also inverts. If you ask for "Going High", the code will switch the processor outputs low to provide this. So the concern is that the pullups would provide a "High" signal to the coils until the ECU came online and could invert the signal.
The workaround for this is to make sure your coils are powered via the fuel pump relay. The fuel pump relay can't come in until the ECU is ready, at which time it will also invert the LED outputs and the signal to the coil will be low.
BTW, when I get the coils I'm going to install the pullups to the Microsquirt and do a test on this to see what happens.
I can configure the spark outputs temporarily and then just play around in test mode.
Last edited by hybrid on Thu Mar 10, 2016 8:58 pm; edited 2 times in total
Yes I understand and your summary is a good one. Just did not understand the differences between Microsquirt and MS2 circuitry in this area. I have not bothered to look because I have never used a Microsquirt. As far as powering coils from ECU switched relay (normally applied to the main fuel pump), this is standard wiring practice. So I say Hmmmmmm.
Any way, testing it out is a good move.
I know it is documented all over the place but just in case make sure you use very short dwell period because these coils are known to fire if they are over dwelled. I remember around 2.5ms is all that is needed.
I have researched this to death with the goal to go that was as well so seeing you go forward is exciting.
The logos and trademarks used on this site are the property of their respective owners.
We are not responsible for comments, advice, opinions, products or services posted by our members, as they are the property of the poster.