Firmware live stream happening this weekend: viewtopic.php?f=13&p=43195
Any questions you have before you begin buying, building and installing.
#41796
Folks,

Apologies if this seems obvious questions but i can't find the answers from the wiki / manual / searching here.

Grounds - If I have a common ground outside of the speeduino, from which i ground all sensors / sheilding and also use the same ground to feed the speeduino power supply, do i need to use the ground pins on the IDC40 connector for the sensors? This would be a seperate ground to the engine block which would ground elsewhere. If i'm using the ground pins on the IDC is their any issue with more than one sensor sharing a pin?

Fuses - I can see some diagrams list some fuses (eg 10amp for coil if doing wasted spark). I can't find any diagram listing what fuse is needed to power the speeduino 12v connection. I have seen a ford zetec diagram in google images suggesting if i recall 5amp.

Finally - the IDC, i'm planning on wiring it to a couple of molex mini fit jr connectors in the case. These then connect to the outside world. To make life easier (perhaps) i've crimped a IDC male connector into the back of a molex mini fit jr pin. This means the molex connectors have male IDC connectors inside the case. I can therefore use a IDC jumper wire to wire the IDC connector on the board to the connnectors to the outside world. The only exeption is the fuel injection pins which have a special wire connecting the two ICD pins to the 1 molex pin. Can anyone see a major issue with this approach? I can provide pictures if what i'm suggesting isn't clear. Intent once everything is fixed is to hotglue the jumper wires togther to give some anti vibration security.

Intent is to wire up a 1970s ford Crossflow (kent) engine in a kit car.

Cheers Mike.
#41834
Welcome Mike!
miker wrote:
Tue Mar 31, 2020 11:00 pm
Grounds - If I have a common ground outside of the speeduino, from which i ground all sensors / sheilding and also use the same ground to feed the speeduino power supply, do i need to use the ground pins on the IDC40 connector for the sensors? This would be a seperate ground to the engine block which would ground elsewhere. If i'm using the ground pins on the IDC is their any issue with more than one sensor sharing a pin?
Best advice is to use the grounds on the IDC40 for your sensors and the one on the main power feed to connect directly to battery (and block if you're running a feed back from the black to ECU). Having the sensors share a single pin is fine.
miker wrote:
Tue Mar 31, 2020 11:00 pm
Fuses - I can see some diagrams list some fuses (eg 10amp for coil if doing wasted spark). I can't find any diagram listing what fuse is needed to power the speeduino 12v connection. I have seen a ford zetec diagram in google images suggesting if i recall 5amp.

10 Amp will be fine. 5A will likely work, but might be cutting is close with some spikes.
miker wrote:
Tue Mar 31, 2020 11:00 pm
Finally - the IDC, i'm planning on wiring it to a couple of molex mini fit jr connectors in the case. These then connect to the outside world. To make life easier (perhaps) i've crimped a IDC male connector into the back of a molex mini fit jr pin. This means the molex connectors have male IDC connectors inside the case. I can therefore use a IDC jumper wire to wire the IDC connector on the board to the connnectors to the outside world. The only exeption is the fuel injection pins which have a special wire connecting the two ICD pins to the 1 molex pin. Can anyone see a major issue with this approach? I can provide pictures if what i'm suggesting isn't clear. Intent once everything is fixed is to hotglue the jumper wires togther to give some anti vibration security.
All sounds good to me. Quite a few folk take a similar approach (With molex and other connectors) and it sounds like you're on the right path with things.
miker wrote:
Tue Mar 31, 2020 11:00 pm
Intent is to wire up a 1970s ford Crossflow (kent) engine in a kit car.
Love me some crossflows! An engine near and dear to my heart, so can't wait to see this all set up!
#41837
Sounds like you're putting some good thought into it. 8-) A reminder on automotive fuses, that they are not designed to blow at the rated amps, and very slowly at currents that are only a bit higher.
PSIG wrote:
Sun Oct 27, 2019 2:44 pm
BTW, keep in-mind that automotive fuses are designed to never blow at their rated amperage :shock:, e.g., a 10A fuse will not blow at 10A. At 11A it may take many minutes to blow, so be sure to size your fuses to the load …
In other words, unless you have some crazy-long surges above your typical operating amps, standard fuses will handle spikes without issue.

David

Using this Littelfuse chart for automotive fuses, you can see a 1A fuse will actually never blow at 1A, and will need almost 3A to blow in 0.1 seconds, or 10A to blow in .01s. :shock: Still, the primary function is to save wiring, so go for that if nothing else:
ATO fuse blow T-C chart.jpg
ATO fuse blow T-C chart.jpg (218.13 KiB) Viewed 323 times
#41940
Thanks for the positive feedback. I'll stick with 5amp g fuses to ensure things are protected (especially as the wire i fitted inside the case is only rated to 11amp) If it blows I'll look to update.

Middle of putting the engine back together at the moment so it will be a few weeks before I attempt spark only ( trigger wheel, map and water temp are my planned initial sensors - although I'm thinking I could just do trigger and map of I've understood correctly)

Cheers Mike

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