Well, better late then never, I've redone most of my work mentioned above, this time digging deeper and working with EasyEDA so I can have a PCB made.
I've drawn a schematic, which will include the alternator control soon:
And started a PCB lay-out:
Which will fit the MX5 NB VVT plug and the Speeduino V0.4.4 as shown in the pic a little heigher on this page.
I made an Excel sheet trying to match all pins:
https://www.dropbox.com/s/ls0dhs3rh4nh5 ... .xlsx?dl=0
It comes with colours that actually mean something:
Green is what I am over 50% sure of, feel free to check.
Red is 12V / running voltage.
Yellow is what I think I don’t need to hook up.
Light blue is for the alternator field control, outside of Speeduino.
Unmarked is what I need to figure out, and ask your help for.
And I have many questions:
- Crankshaft and camshaft sensors from the engine: I’ve now hooked these up to VR1+ and VR2+ respectively, and connected VR1- and VR2- to ground permanently. Is that correct?
- The radiator fan. 2B on the MX5 connector is the fan pin, but do I want to control that from the Speeduino? We have CLT sensor, but wouldn’t it be simpler to throw a sensor in the radiator at the exit, hook up a relay and the fan to a switched 12V source, not use Speeduino for this?
- The heating of the O2 sensor, I’d like to ground that when the engine is switched on, but disconnect when the engine is at running temp. Is this logical? I think so, because the sensor will retain it’s own temperature by then due to the exhaust gasses. Can I use HC-1-OUT to do this, and if so, how? Or should I just ground it and leave it?
- There is a knock sensor signal coming from the MX5, 4M. Can we use that?
- I just connected all 12V / running voltages to each other, except for the battery plus which I don’t use. Right?
- The VVT control. The positive side of the valve is connected to the 12V, Speeduino should PWM the ground. Can I use HC-2-OUT for that?
- I will use the MAF sensor wire for boost control, as it is in the right location (yes, I’m going to turbo the lot). The boost solenoid (Pierburg 7.28197.16.0) has a two wires. Now there is pin 35 on the Speeduino called ‘boost’. But I read in the boost control page this is for a 3 or 4 wire boost control solenoid. Should I buy another solenoid, or can I use the one I have?
So, lot of work done, but I need to have a better understanding of what I am doing before I can finalise this.
All input is appreciated, cheers,