seth1001 Posted March 5, 2011 Share Posted March 5, 2011 I'm getting close to starting the wiring for Megasquirt into my 1980 280ZX N/A. I just wanted to post this sketch I made and make sure that I have the concept correct. Does the picture below look right?...Do I need to wire anything differently? If so...please describe it to me and I will make a new picture until I have it correct. Thanks. Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted March 5, 2011 Share Posted March 5, 2011 It's wrong. It should be +12v KEYED -> Resistor(s) -> Injector(s) -> Megasquirt. The MS box grounds the injectors, not provides power. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted March 5, 2011 Administrators Share Posted March 5, 2011 Mario is correct. Quote Link to comment Share on other sites More sharing options...
mobythevan Posted March 5, 2011 Share Posted March 5, 2011 I know its old school, but I like Tony and his simple ascii diagram: Tony D. ascii diagram for wiring your injectors: 12V+ ----- Resistor Pack ----- Inj1+ Inj1(-)-----\ 12V+ ----- Resistor Pack ----- Inj2+ Inj2(-)------SPLICE ----- INJ1(Gnd for Injectors thru MS) 12V+ ----- Resistor Pack ----- Inj3+ Inj3(-)-----/ 12V+ ----- Resistor Pack ----- Inj4+ Inj4(-)-----\ 12V+ ----- Resistor Pack ----- Inj5+ Inj5(-)------SPLICE ----- INJ2(Gnd for Injectors thru MS) 12V+ ----- Resistor Pack ----- Inj6+ Inj6(-)-----/ Quote Link to comment Share on other sites More sharing options...
seth1001 Posted March 6, 2011 Author Share Posted March 6, 2011 I see...interesting...so this is the way it should be? Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted March 6, 2011 Administrators Share Posted March 6, 2011 That works. Quote Link to comment Share on other sites More sharing options...
seth1001 Posted March 6, 2011 Author Share Posted March 6, 2011 Where did you guys get your switched wire? I know the dropping resistors have a pair of switched 12v's going to them but I may have to use those resistors somehow if I can't find any others...which I haven't so far...radio shack doesn't have any. I think I'd rather get rid of those 30 year old things and build some sort of resistor box and just mount it somewhere...I've read some posts on the matter but I can't really visualize what they're describing...I guess I could mount the resistors on the fuel rail...with some..mighty putty or something. Any suggestions? Quote Link to comment Share on other sites More sharing options...
mobythevan Posted March 7, 2011 Share Posted March 7, 2011 I used dropping resistor packs from an eclipse on my LSx V8. I also use a relay board, it has 12 volt switched for the injector power. Just the way I did it, not saying it is a good way. Quote Link to comment Share on other sites More sharing options...
seth1001 Posted March 7, 2011 Author Share Posted March 7, 2011 Well riddle me this...couldn't I just leave everything wired up through the stock dropping resistors the way it is...and then chop the negative sides and splice them to the megasquirt...bodda bing?...or does it not work that way? Quote Link to comment Share on other sites More sharing options...
mobythevan Posted March 8, 2011 Share Posted March 8, 2011 That would work if you have stock dropping resistors. I didn't think z cars had them, but maybe I am thinking of the earlier years. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 8, 2011 Share Posted March 8, 2011 The pin-out for the 1980 ZX dropping resistors is on Page EF-41 if you don't want to chop any wires. There's a description of the resistors on EF-19 and wiring diagrams on 21 and 22. Looks about like your last drawing in function. Quote Link to comment Share on other sites More sharing options...
seth1001 Posted March 8, 2011 Author Share Posted March 8, 2011 Moby: Yeah the ZX's all had dropping resistors as far as I know. Well that simplifies matters. I've tested the resistors and they're still putting out 6 ohms of resistance so I guess I'll just hook them and and splice the wires at the injectors. I don't really like the idea of using the old wires but I guess it's okay. I also don't like having to use the old EFI computer to put out the voltage to the resistors...but as long as it works I guess. The wiring for everything else is pretty much self-explanitory but I'm still not sure how I should get the wires past the firewall. I've done some searching but haven't found anything good yet. What did you guys do? Did you drill new holes or use ones that were already there? Also I've heard that wide-band O2 sensors have some issues with interference...did you guys have to drill a separate hole for the O2 sensor wire and kind of...keep it separate from the other cables or something? Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 8, 2011 Share Posted March 8, 2011 The EFI relay, not the ECU, supplies power to the dropping resistors. Diagrammed on page page 19, if you really want to know. I'll butt out now, just wanted to be sure I was getting my point across. Of course, sometimes it's more fun to put things together without the instructions. Quote Link to comment Share on other sites More sharing options...
seth1001 Posted March 8, 2011 Author Share Posted March 8, 2011 Oh that's right...it should just be the "-" wire on the injectors that routes back to the ECU...makes sense...Any comment on the firewall routing? Quote Link to comment Share on other sites More sharing options...
Cannonball89 Posted March 8, 2011 Share Posted March 8, 2011 My 1983 turbo ZX did NOT have dropping resistors. I'm not sure if that was an 83 only thing or a turbo only thing but there were not dropping resistors on 1983 turbo ZX's. Quote Link to comment Share on other sites More sharing options...
seth1001 Posted March 8, 2011 Author Share Posted March 8, 2011 I think the turbos didn't have them because they had different injectors that didn't require them... Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted March 9, 2011 Share Posted March 9, 2011 I think the turbos didn't have them because they had different injectors that didn't require them... Nope. 82-83 Turbo ECU's were different then the 81s in that the resistors were inside the ECU. Quote Link to comment Share on other sites More sharing options...
seth1001 Posted March 9, 2011 Author Share Posted March 9, 2011 Well here's something interesting. I clipped the wires that go to the individual fuel injectors after reinstalling the dropping resistors and all that. Then I turned on the ignition so I could check the voltage and figure out which wire I should connect to the megasquirt...but both wires were testing at 13V...I don't know what's going on here...I guess I should take a look at the wiring diagram but that things a pain in the ass to look at. Does anybody know how I determine which wire to hook to the megasquirt? Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted March 9, 2011 Administrators Share Posted March 9, 2011 Then I turned on the ignition so I could check the voltage and figure out which wire I should connect to the megasquirt...but both wires were testing at 13V...I don't know what's going on here... That is normal. I guess I should take a look at the wiring diagram but that things a pain in the ass to look at. Does anybody know how I determine which wire to hook to the megasquirt? Yes. Yes, you should. It's not that tough, honest. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 9, 2011 Share Posted March 9, 2011 (edited) Is your ECU still installed and plugged in? Unplugging it might kill the power to one side, the side you'll be connecting to Megasquirt. Page EF-21. There are mini-diagrams throughout the FSM, you don't have to dig through the big one. p.s. Didn't mean to stomp on your reply Ron - timing... Edited March 9, 2011 by NewZed Quote Link to comment Share on other sites More sharing options...
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