New member here. i apologize in advance if i am posting in the wrong section but I was directed here from another MS forum to post my question here.
87 Conquest still with a 4cylinder in it. I am kind of new to this platform including megasquirt and seeking the assistance of the forum. Having a no spark condition, but I am getting injector pulse. First I tested at the end of the spark plug wire to plug and was getting no spark. So I traced back further to the ignition coil wire and found I was getting no spark from the coil feeding the distributor. I tested the neg - terminal of the coil and its getting ground pulse as you crank. I tested the pos + terminal of the coil and am getting 12v. One would think that I am getting the correct signal/ power to the coil but the coil is new and I tested the resistance on the coil and it measures within spec (.78 primary ohms and 10,500 on secondary) I am testing for spark with an actual spark tester that shows a light when spark runs through it. I have verified this tool works by testing on another car.
Here are a couple pictures of the ECU/setup. Any and all information you can give me about it would be helpful.
I think I see some mis-wiring but the HT lead on the coil is in the way. First, I take it the red wire is supplying +12V switched to the coil? You also have the factory tach lead (the little gold box thing) on the + side of the coil then, that actually goes on the - coil terminal. I see the wire marked "coil -" appears to be going to the other coil terminal but so does the black wire/white stripe which is the factory +12V switched power to the coil. If that is so then the coil can't fire.
So, either the red wire in the picture or the black wire/white stripe in the picture (if it is still active) goes to the + terminal of the coil AND that should be the only wire connected to the + terminal of the coil. The - terminal of the coil gets the wire marked "coil -" and the little gold box for the factory tach. If that doesn't make the coil fire then its a bad coil, I've seen those MSD blasters go bad often. We had one at the last Texas meet that would fire TO the distributor cap but didn't have enough power to fire THROUGH the distributor cap/rotor, took forever to diagnose that.
Graduate of EFI University.
I build, repair, install and tune Megasquirt systems in North Dakota and beyond!
" I tested the neg - terminal of the coil and its getting ground pulse as you crank."
What about that statement? For that to be true, the MS would have to be turning on the coil properly. Were you testing at the coil term, or at the harness wire that would connect there, with the harness disconnected? Something isn't making sense here.
