Ignition Coil Short

[Roguepriest1287]

The last week has been hell for me and my Z . It started off with me getting the wrong fan clutch from the dealership. Once I had the right one, I went to install it and broke my upper radiator hose so I had to order that part and wait lol. Once I got the part I took the opportunity to flush the coolant system and put the new radiator hose on. After that she was running great, and I was planning on a drive through Rocky Mountain National Park this weekend. Then disaster struck on the highway trip up to Denver. All of the sudden out of no where I started loosing power and could feel the engine misfiring as I pulled off to inspect what had happened. This is what I found...





The ignition coil, the connector, and some of the wires had melted and turned into ash. I got my Z towed up to my brothers garage and pulled out the ignition coil on the number 5 cylinder.





That is what was left of the ignition coil. I've got a new ignition coil and harness coming in the mail. Anyone ever have something like this happen to them?

[twinturbozxtacy]

Unfortunately i have not too long ago in fact. same spot too, my cause was a leaky fuel clamp that caused the coil to short. the leaking gas also caused the coil boot to swell and made it impossible to remove the coil as a whole. the wire shorted all the way to the ecu, new harness was 500 and new coils another 100 from the jy.

[ThisIsSparTTa]

I had that happen on number 3. Never figured out why. We were under the hood though so when I saw it smoke we cut the power, and it didn't fry that bad, just bubbled up. I was fighting other issues at the time with PTU wiring and what not, but I think it may have been possibly unrelated and it was just its time. Although lots of people will say on the forums that coil packs rarely fail, I had that one fry, and I had at least one other bad one after 165k, so the miles or age may just be getting to them.

[Roguepriest1287]

I had that happen on number 3. Never figured out why. We were under the hood though so when I saw it smoke we cut the power, and it didn't fry that bad, just bubbled up. I was fighting other issues at the time with PTU wiring and what not, but I think it may have been possibly unrelated and it was just its time. Although lots of people will say on the forums that coil packs rarely fail, I had that one fry, and I had at least one other bad one after 165k, so the miles or age may just be getting to them.

That kind of where I am at with this, I think it was just an unlucky moment for me. I spent most of the night and good chunk of today searching around for possible shorts anywhere else with a couple of people and none of us could find anything. Now all I can do is wait for the parts to come in the mail lol I opted for overnight delivery so I can get it running ASAP gotta another chance for a cruise this weekend . I am crossing my fingers that all goes well.

[itsa300zx]

If you havn't already done so, pay close attention to the bundle of wire running along the water pipes to the PTU. And since you did some work there, I would doulbe and tripple check. I've seen a coil pack starting to melt like that from a short in that area; caused by improperly securing the wires. Just a thought.

[Roguepriest1287]

If you havn't already done so, pay close attention to the bundle of wire running along the water pipes to the PTU. And since you did some work there, I would doulbe and tripple check. I've seen a coil pack starting to melt like that from a short in that area; caused by improperly securing the wires. Just a thought.

We double checked the wires on the ptu sub harness and found a short in those. What had happened was whatever was holding those wires in place gave away and they were scrapping on one of my belts. This cause a small part of the wires to melt together. Once we found that we cut into the wires and removed the damaged part then soldered new 18g wire into its place. We plugged the new ignition coil in and after a few minutes of running the ignition coil began to melt. I am at a loss right now .
I am not sure were to look next or what could even been causing this problem. There are no leaks anywhere near the coil so that has been ruled out. idk if it is a problem with how we soldered the new wires in, maybe I should just by a new ptu sub harness but I do not want to waste the money if the problem could be somewhere else. Any ideas on where to look or what could be causing this?

[itsa300zx]

I would remove the PTU and check that out as per the FSM, look at the sticky on the top of the tech section. THe original short may have damaged that also.

[nissanfreak12]

Trace the wire back from he coil. Finding out where the short is out is always a PITA, but sometimes necessary. Its very possible the short could be a sensor or the PTU itself. You will never know until you make sure the wires are not shorting somewhere.

[Roguepriest1287]

I would remove the PTU and check that out as per the FSM, look at the sticky on the top of the tech section. THe original short may have damaged that also.

I went ahead and checked out the PTU and it was shot. I traced the wires and could not find any other shorts. I ordered this today http://www.conceptzperformance.com/Cart ... ype=NIS300 and it should be here soon since I opted for over night delivery. I got the new coil packs today so hopefully this will be the end of this battle.

Is there a way for me to test the coil packs once they are connected before I put them in. I don't wanna to spend the money to buy another so I would like to make sure its not going to melt again before putting everything all back together.

[itsa300zx]

Im not 100% sure. Maybe once you have the new PTU plugged in, turn the ignition to "on"(not running) then check the voltage at the pack connector. Compare that with one of the other pack connectors.
Remove fuel pump relay and disconnect CAS. Then remove the #6 spark plug, and confirm normal spark pattern with plug grounded to plenum and a helper cranking to start the car. Also compare the spark pattern with another location.

[nissanfreak12]

Which PTU did you have? Version 1 which has a ugly silver face or Version 2 which is all black. I cannot remember which year they changed those from the factory.

In the FSM it should have the numbers for the coil pack, what they should test at.

[nissanfreak12]

Off topic, but are you going to make t to Denver if you get the car running this weekend? SpecialtyZ will be here doing dyno tuning, don't have to get a tune, but may be fun to hang out with other enthusiast.

[Roguepriest1287]

Off topic, but are you going to make t to Denver if you get the car running this weekend? SpecialtyZ will be here doing dyno tuning, don't have to get a tune, but may be fun to hang out with other enthusiast.

I just noticed you lived up in Denver. I was wondering if there were any Z owners from Colorado on this board. My Z is actually in Broomfield right now all of this repair has been done from there. If I get it up and running I think I may just go I think it would be fun. You should PM me with the details .

[Roguepriest1287]

Well tonight is the night I am about to leave for Denver to hook up the new PTU and Harness. I really am hopping this is it for this battle, because if its not idk what I am going to do next lol. Once I got the PTU I will do the tests above and if those check out Ill do the final test of running the car with all the bits in their place. Wish me luck

[nissanfreak12]

All the luck to you buddy!!

[Roguepriest1287]

Well after all of that I installed the new coil pack and turned the car on. 5 mins later the coil pack started smoking and melting again . I took my car in yesterday to get a professional diagnoses hopefully the turn up something and give me some direction to go. I looked and looked and could not find a short anywhere else. Keeping my fingers crossed then can figure out whats causing this happen, I am really missing the hell out of my Z right now lol.

[Roguepriest1287]

After a long and bloody battle I am happy to say that I got to drive my Z for the first time today in almost 2 weeks. Turns out there was a grounding issue caused by the original short. I can honestly say I've never been happier lol

[t.mcginley.jr]

After a long and bloody battle I am happy to say that I got to drive my Z for the first time today in almost 2 weeks. Turns out there was a grounding issue caused by the original short. I can honestly say I've never been happier lol

You found out the hard way that proper grounding is no joke lol

[itsa300zx]

Do you happen to know which ground it was?