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Old 08-14-2013, 07:02 PM
oab_au oab_au is offline
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Re: The beginnings of a Megasquirt how-to guide

Quote:
Originally Posted by BRZCory View Post
I have no idea what you're talking about.

Unless you're talking about a GIPO board, but I haven't gotten that far in my research. The Megasquirt "2" IS the expansion board that plugs into the CPU slot. You're still going to need a bunch of transistors (I assume) to go from logic-level to power-level, but that's easy.

It *would* be really helpful if someone has access to an oscilliscope, to see exactly what sort of voltage/power is going to the stock ignitor. That way we could figure out exactly how much juice we need to flow to get this all to work.

And we'd be able to see how long the stock signals cut power to the ignitor (dwell time)
Haven't had a scope on it, the ECU signal to the Ignitor is just a low level switching voltage, same as the Injector signal.

The coils are feed 12V, the Ignitor grounds them when the ECU Dwell signal is sent, the Ignitor looks at the current the coil is flowing till it reaches about 4 amps, it then holds that current till the ECU Dwell times out, to turn the Ignitor off.
So your switching transistors need to be able to dissipate the heat, while the Ignitor is holding the current at about 4amps. All the heavy current is handled by the Ignitor.

Quote:
Originally Posted by BRZCory View Post
As for some possibly helpful links:
Also, am I correct in assuming the stock IACV is a PWM control? It doesn't seem to have enough wires for a stepper style.
It is neither, it is balanced between two voltages that are varied between 1 and 10V. Idle is 5v each side.

Harvey.
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