taylor76zharris Posted March 31, 2013 Share Posted March 31, 2013 I'm reaching the end of my megasquirt install but I've hit a snag. Where is the best place to tap 12 volts for the injectors and for the distributor? I don't want to source 12 volts for them all from the same place and I don't think that's how it should be done but I'm no expert. Also I'm also doing the install with a relay board from DIY autotune. So where's the best place to get 12 volts for the distributor and the injectors and how many times can I tap the same wire for 12 volt? Thank you. Quote Link to comment Share on other sites More sharing options...
motomanmike Posted March 31, 2013 Share Posted March 31, 2013 Relay board gives you 4 12v pins for whatever you need. Look on the DIY write up Quote Link to comment Share on other sites More sharing options...
taylor76zharris Posted April 1, 2013 Author Share Posted April 1, 2013 Oh alright. So could i use one of those pins for the green/black wire on the distributor that has the pull up resistor in line? Quote Link to comment Share on other sites More sharing options...
motomanmike Posted April 1, 2013 Share Posted April 1, 2013 you could. The injector wiring shown on the DIY site powers 2 banks of 3 injectors only. So 2 wires to 3 injector positives, 2 wires to the other 3 injector positives, That took up the entire 4 slot 12v feed.. I don't think powering the distributor would hurt in either of those 4 positive slots. Its only an LED so it doesn't draw much I would just be concerned with noise but you might be ok. Read about noise. You probably will have it at some point but maybe you'll get lucky. Quote Link to comment Share on other sites More sharing options...
taylor76zharris Posted April 1, 2013 Author Share Posted April 1, 2013 Awesome thanks! I tried to do my best to get away from any interference with the distributor wire but I understand Noise is a pretty common problem with this type of it install. I hope I get lucky and don't have any but I'm not counting on it. 1 last question on the relay board there is a large port for an engine ground will that take the place of the 5 ground wires in the DIY wire harness? Because I noticed when looking at pictures and when doing some research no 1 has the 5 wires anywhere on the relay board Quote Link to comment Share on other sites More sharing options...
motomanmike Posted April 1, 2013 Share Posted April 1, 2013 Yes, the original wiring diagrams you are looking at are for using a the DB37 harness. You only have 1 ground, 1 switched power, and one constant power to the relay board. The relay harness gets the power it needs to feed the ECU from the relay board. Make sure you run your sensor wires and sensor returns back to the relay board in the appropriate spots. The relay board really eliminates a lot of gray area as far as the wiring goes. Good luck. I'm still fighting a misfire with my install. Not sure what it is yet but hopefully yours will fire up and run right after a little tinkering. Good luck. Quote Link to comment Share on other sites More sharing options...
taylor76zharris Posted April 1, 2013 Author Share Posted April 1, 2013 Thanks man, i hope so. This is my third complete re-wiring of the whole thing and hopefully its the charm. Not that ill be much help but when is it misfiring, at idle, full boost, or in between? Quote Link to comment Share on other sites More sharing options...
taylor76zharris Posted April 9, 2013 Author Share Posted April 9, 2013 Ok, This is exactly how i have my board wired in minus the tach signal which has been giving me fits from day one, its just confusing to me because the ground and signal wire run in the same sheath and their twisted and foil protected and all that good stuff. My questions/ can i run my sensor returns as shown in this diagram or does each sensor need to have its own separate return ground? Also, am i correct in thinking that the white tach signal is the only wire that gets connected to terminal 15 on the relay board? If so what do i do with the black wire that runs along side it? I have the black wire grounded through the distributor. Quote Link to comment Share on other sites More sharing options...
Matt Cramer Posted April 9, 2013 Share Posted April 9, 2013 All returns can be tied together. You don't need to use the black wire, or can use it as a distributor ground. It was really included for VR sensors. Quote Link to comment Share on other sites More sharing options...
OhBilly Posted April 9, 2013 Share Posted April 9, 2013 (edited) Run your sensor returns as shown in the diagram. These returns are grounded through the relay board. As long as your relay board is grounded well, you shouldn't have any trouble. Edited April 9, 2013 by OhBilly Quote Link to comment Share on other sites More sharing options...
taylor76zharris Posted April 10, 2013 Author Share Posted April 10, 2013 Alright will do. Thanks everyone! Hopefully ill be starting it tomorrow, with any luck. Quote Link to comment Share on other sites More sharing options...
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