I have a 88 YJ I swapped a 93 ZJ 4.0 in over 120k ago. In the last few months it started having an issue with blowing coils. I vaguely remember it doing it right after I swapped it in. It currently blows one every month. I am at my witts end on this problem and have exhausted every thing I could think of and am looking for new ideas.
What I've done-
New cap, rotor, wires, plugs
Replaced capacitors in PCM, part of a different problem
I also read the tsb on it that mentions the resistor wire to keep it from happening? The part is no longer available so I wired in series to the + side of the coil a .8 ohm ballast resistor. I'm thinking maybe I just need to go up more? I'm also running the spade type coil.
My battery is older but I don't think it makes a difference.
The coil opens when it's hot and if you let it cool down for a while it will crank back up and start. It also occasionally explodes them. Also sometimes the coil is so hot it will instantly burn you. As in way hotter than the engine. Any ideas would be greatly appreciated.
The resistor should work in bringing down the voltage and effectively lowering the current. The ecu is grounding the coil. Check the ecu grounds to make sure they are all good. No ICM on yours. I am wondering if you are getting the wrong coils. The ealier Jeeps did have a resistance wire but the later models were designed to run on 12 vdc. I would x2 Old4X original post of looking at a different coil then the one you are using.
I have the tach wired to the - side of the coil and I'm wondering of that might be a issue as when I disconnect the readings change. Also iirc I vaguely remember there being a tach out on the PCM. It's been way to long since I wired though so I've forgotten a lot.
Jeep is a 88. All engine wiring from the bulkhead fwd is 93 4.0 with wires spliced at the bulkhead. I originally got it with the spade type and have been using those. I've heard the round type have a different resistance value in them. Thinking maybe I should try the round type. All ECM ground test good. Less than .2 dcv drop from ECM to batt.
The tack should just be a minimal draw. You can try disconnecting it and see if it has an impact. You can see why there is confusion on the coils. They do appear the same but they are definitely different. I would recommend getting a master blaster coil.