i was misfiring earlier so i bought a new coil pack and replaced it.
1 day later, it started misfiring again so i popped the hood and saw smoke coming out from the new coil pack i just bought.



what could of caused this? i don't want to replace it and this happening again.

 

Manufacturer defect? What did the old one look like?

 

you are 00vi swapped so are you running 4th or 5th coils?? what does the plug look like??

 

That's a 4th gen front coil.

Seen it happen before:

 

A fault with the plug could cause that. If you have an ohmeter compare the resistance to ground of plug for blown coil with that of another cylinder.

 

Done any recent ECU or wiring harness work? The pic above is from a 350z with a pinched UTEC harness (leading to a damaged ECU), had to change both out before it stopped frying coils.

Check to make sure it isn't getting a constant signal from the ECU, that'll cause them to get hot and burn up.

 

so just possibly a defect? surprisingly don't have an ohmeter yet



not since i wired up my suprastick which was several months ago. car has been running fine ever since. check what isn't getting a constant signal?

 

The coilpack.

 

^^^ sorry but how do you check for that?

 

Check the signal wire with a multimeter.

 

You need to spend ~$10 at Radio Shack or Walmart and buy a VOM (volt - ohm - meter). Also, page 329 of the FSM (feild service manual) of the EC section tells you all about testing the system.

IMO, unless the other pack looked the same, I'd guess bad part out of the box. But, if it happens again, you got a warranty? You should I would think. Test it and see what's up ... can't hurt.

 

alright, i'll do that, its time i get one anyways.
also, which year FSM were you looking at? pg 329 is about the evap diagnostic...
i found on page 297 where it talks about the ignition coil harness diagnostic.

yes, it has a 1 year warranty.

 

i'm looking for battery voltage right? is this with the ignition on?

 

I think the coils fire with a 5 volt signal.
Somebody correct me if I'm wrong.....

 

There are three wires going to the coil pack with the engine off check the resistance to ground of each of the wires. Then check the resistance between each of the wires to each other. Compare your readings to that of another cylinder if you measure anything that appears way off, like a short where one should not be, that could be the problem.

The middle wire which is black should read a short to ground the other two wires should not. Again compare to another cylinder.

You really can not check much of anything useful with a multimeter once the engine is running.

I'm not sure what a Suprastick does or where it connects but if it has anything to do with the firing of your plugs that is probably what is causing the problem. Most electrical problems are caused by someone working on the electronics or wiring. Is it possible one of your coil wires got pinched or exposed? Check for that.

 

Looks like that Suprastick connects to the ECU, your coil firing signals also come from the ECU. I would consider removing the Suprastick at least temporarily until you find the cause of the problem. Chances your Suprastick or Suprastick wiring is causing the problem 80%, chances something else is causing the coil to blow 20%.

Was the original coil blown also?

 

Don't forget to pull that plug and check it. I would consider replacing that plug regardless.

 

I highly doubt its the Suprastick. Like he said, he's had it wired up for a couple of months with no issues. Besides, the Suprastick only taps into the TPS, Crank sensor, and VSS on the ECU harness and power and ground if you decide to tap into the ECU harness for that. He would know if he messed up the wiring for the Suprastick because the Suprastick wouldnt function correctly. Unless he inadvertently damaged some other wires while installing the suprastick, my vote would go to a faulty coil pack.

 

I agree it could be a faulty coil pack, was the original one blown? Just trying to cover all the possibilities because he does not want to install another one and just have it blow again.

 

G4 .... No, you're not looking for bat voltage here. The FSM goes through how to test the component, the harness, and will tell you what the correct output voltage from the ECU to the coil pack trasistor should be. There are actually two circuts here, not one. Not sure what year FSM I have, IIRC, it's a 98'. lol Sorry bout the pages being off.

I don't have the time atm to look up the pinouts for the ECU to trasistor, but I know it's in there. Just gotta dig through EC to find it I guess. I still feel it could just have been a bad part. Not a bad idea to test it all first and see though. The FSM tells you to pull the harness at the ECU and the coil pack and check for continuity - have fun with this! lol The voltage reading will be much easier. Yes, the key needs to be "on" in order for the sig from the ECU to hit the trasistor that hits the coil pack. Like I said, you'll need to check the ECU section in the FSM to get the proper voltage. (I think on our cars it's supposed to be 5 - 5.2 v ----- Don't quote me, it's been a while since I did one on a Max. lol) Hope some of this helps.

 

to tell you the truth, i don't remember if the original coil blew or not cause i threw it away right when i bought the new one...although i do remember seeing smoke coming out of the valve cover from that spot so my guess is yes, it did blow up as well.

along with what whlimi said, i also have the ignition switch from the ecu connected to the suprastick but still, don't think that is the issue.

i don't have much time for the next couple of days due to exams but i will test out the harness this weekend. hopefully its not a short of some sort.

 

oh dear...
feels like i'm in a physics lab all over again...

 

A coil blows due to excessive current. Most likely cause of excessive current is that coil output is shorted to ground. One coil output goes to the spark plug the other to the colored (not red or black) wire with stripe, on your coil connector. Make sure that neither of these two are shorted to ground. Compare these readings to surrounding coils/plugs.

 

ok, i bought a digital multimeter today but can't really do any diagnosing since its dark.
i also went a replaced the blown coil pack and too my surprise i noticed premature stress just like the previous coil so i unplugged it before it could blow. so i guess it is the harness thats the issue.

i also realized today the part where the wires of the coil harness are held from the plastic zip tie thingy seems really pinched so i'm hoping thats where my short is.

also, JTZ, i looked through the EC section, couple of questions:



what is the diff between the H.S. connector and the T.S. connector? (the pin layout is diff)

also, how the HELL am i supose to check for continuity from the ecu harness to the coil harness? its too far away...

 

Harness side vs terminal side; notice the pinouts are the exact opposite?

Get longer leads, or get some wire.

 

ah lol.

 

Check the easy stuff first. Have you checked the condition of the plug? You have a multimeter but maybe no idea how to use it.

There are three wires going to the coil pack with the engine off check the resistance to ground of each of the wires. Then check the resistance between each of the wires to each other. Compare your readings to that of another cylinder if you measure anything that appears way off, like a short where one should not be, that could be the problem.

The middle wire which is black should read a short to ground the other two wires should not. Compare to another cylinder.


Unless you find something out of the ordinary when doing the above there is no reason to check continuity to the ECU.

 

Thanks Paul!

 

alright well i did some resistance tests today but haven't gotten to the continuity diagnosis b/t the ecu harness and the coil harness yet.

Cylinder #2 is the one i'm having issues with the coils blowing up...


cylinder #2:
pin #1 power supply: 11.7 V
pin #1 resistance to ground: 38.3 ohms
pin #2 resistance to ground: 0.9 ohms, continuity b/t middle terminal and ground exists.
pin #3 resistance to ground: 780 ohms
resistance between pin 1 & 3: 819 ohms

cylinder #4:
pin #1 power supply: 11.7 V
pin #1 resistance to ground: 38.5 ohms
pin #2 resistance to ground: 0.8 ohms, continuity b/t middle terminal and ground exists.
pin #3 resistance to ground: 778ohms
resistance between pin 1 & 3: 818 ohms

cylinder #6:
pin #1 power supply: 11.7 V
pin #1 resistance to ground: 38.5 ohms
pin #2 resistance to ground: 0.8 ohms, continuity b/t middle terminal and ground exists.
pin #3 resistance to ground: 1000 ohms
resistance between pin 1 & 3: 1030 ohms

do those seem alright? pretty close and consistent if you ask me (except for the last part).
is there still a need to check for the continuity?

 

Those values all appear to be normal. No shorts or opens. No need to check continuity to the ECU because if you did not have continuity you would have measured an open circuit, which is infinite resistance, for one of those connections.

 

They look good, I would still check the harness. You can use any wire to 'probe' the pin set and attach it to your meter for a long lead. It will be a lot of back and forth pinning I'm afraid but it could be worth finding the source of your problem. You might check the "L" bend in the wiring where it goes through the firewall. Common source of problems at this point and I believe there is even a TSB on it. Can't recall ....

 

alright well i already told nopike but i drove around today w/ the coil back in and plugged up to test it out and no issues so far. i'm going to give it a couple more days of driving around and then if it blows again, i'll check the continuity. hopefully everything will work out

 

Something was shorting out temporarily. Maybe just moving the wires and connectors fixed it. If you have trouble in the future consider removing your Suprastick connections. Also if you have the problem again take those measurements again. Today they read good but if the problem occurs again they may not.

Something was shorting out temporarily. Maybe just moving the wires and connectors fixed it. If you have trouble in the future consider removing your Suprastick connections. Also if you have the problem again take those measurements again. Today they read good but if the problem occurs again they may not.

 

Seems like a freak thing. I would goto autozone or kragen, get another coil pack for 25% discount (find the coupon online), and call it a day. It's got a 1yr warranty. If in fact you do have something else going on causing the problem, I'll malfunction again, confirming u got an issue w/your system, and then go hunting. In the mean time, get the coil pack replaced under warranty.
Dr J

 

looks like it over heated and expanded

 

2nd coil pack blew up again.

found the issue. no continuity existed from the ecu to the ground wire on cylinder #2 of the ignition coil harness.

 

uhhh what does factory parts have to do with the issue?

 

My bad I got confused between another thread about a cam sensor. Good job on the find.

So no continuity huh? Dam... looks like you have the notorious broken harness. Have you tried the twisting the harness method while checking continuity?

 

no problem

lol, theres only so much of the harness i can twist and most of that is up front...

dunno how the hell i'm gonna fix this

 

LOL I know that EXACT feeling. This is why i dread 4th gen maximas with weird check engine light problems at work lol.

Don't stress out too bad though bro, easiest way to do it (prob ghettoest too) is just to run a new wire from your ECM to the coil subharness. Its not horrible. Just find the wire comming out of the pin from the ECM connector thats bad, give yourself plenty of wire and cut it off leaving enough of the ecm pin wire to butt connect/solder a long wire to. Then poke a hole through the harness bulkhead boot with a long screwdrive, put the long wire through the hole carefully, try not to break it or damage the insulation, and wrap it around the stock harness with black tape. Then when you reach the coil subharness, locate the bad wire, chop off the old wiring leaving enough wire to connect your long wire to. Then just make it look clean by wraping black tape around the exposed wiring and such. And thats it!

Or you can go the right way about it and just unwrap the entire harness including the looming and search until you find the break This can suck cuz alot of times the insulation isn't broken, its the wiring inside that is so its almost impossible to find unless you poke through the wire insulation checking continuity every 5-10mm at a time lol.