# Coil pack dead after 50k miles ??



## obermd (Mar 3, 2012)

Did you straighten out the springs before you put the coil pack back on?


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## brian v (Dec 25, 2011)

How did we miss you for so long ? because yer a funny guy ..


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## Poje (Aug 2, 2012)

obermd said:


> Did you straighten out the springs before you put the coil pack back on?


I dont know, it was a mecanic that did it, didnt watch...


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## Zforce75 (Dec 27, 2014)

I had my coil pack arc to the block at right gut around 50,000. It did some crazy random misfire stuff and then finally gave out on the no 2 cylinder completely. I took it into service and I was in and out of there without being charged a dime despite my being over the 36,000 b2b. In fact, it was the most pleasant dealership experience for me to date. Since my car is doing the same thing again (Started yesterday) I am hopeful that Chevrolet recognizes that this is a fairly common problem on these engines, and doesn't abandon their customer base. Good luck!


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## Poje (Aug 2, 2012)

Zforce75 said:


> I had my coil pack arc to the block at right gut around 50,000. It did some crazy random misfire stuff and then finally gave out on the no 2 cylinder completely. I took it into service and I was in and out of there without being charged a dime despite my being over the 36,000 b2b. In fact, it was the most pleasant dealership experience for me to date. Since my car is doing the same thing again (Started yesterday) I am hopeful that Chevrolet recognizes that this is a fairly common problem on these engines, and doesn't abandon their customer base. Good luck!


Thx for this info!

I went back to my Mecanic and we checked, the coil was installed properly and he said to me that normaly when a Coil pack dies, the car doesnt idle properly and has difficulty running.

Maybe its not that at all...


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## XtremeRevolution (Jan 19, 2012)

Remove the coil pack again. Slide the boots off carefully, being sure not to rip them. Check the springs and resistors for corrosion. If there is any, get some penetrating spray and scrub them down with a brass brush to clean them up as well as you can. Douse the boots inside and out with silicone spray, then put it all back together.


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## Poje (Aug 2, 2012)

XtremeRevolution said:


> Remove the coil pack again. Slide the boots off carefully, being sure not to rip them. Check the springs and resistors for corrosion. If there is any, get some penetrating spray and scrub them down with a brass brush to clean them up as well as you can. Douse the boots inside and out with silicone spray, then put it all back together.


Thx for the infos, i'll check that!


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## Poje (Aug 2, 2012)

The one thing that makes me think its the Coil pack is that, when my car started Hesitating, b4 i changed my plugs, the old plugs were Original Delco Iridium plugs from the GM dealer and they were only 8 months old. Normaly they last way longer then that, so...


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## NickD (Dec 10, 2011)

With a conventional 60 Hz transformer with 120VAC applied, if you want say 1,200 VAC on the secondary winding, use approximately ten times the coil turns in the secondary. 

Ignition coils don't work this way, pulsed with a DC current that switches off instantly producing an extremely rapid collapsing magnetic field. Even with only a ten turn, turn ratio, in theory can hit an infinite number of volts output. Only limit is when the spark plug fires, dictating why the lowest possible gap should be used.

If not or due to a defective spark connection, the voltage in the coil can be extremely high and even arc through two adjacent coil causing the dreaded shorted turn. This shorted turn will eat up all the energy vastly decreasing the output voltage. Can be tested with a spark gap tester hit with an ignition switching type pulse. Should expect to see a 3/8" spark.

Can look at a coil all day and not know if its good or bad until you test it. Unfortunately with the Cruze, have four such coils, and if just one is bad, the entire module has to be replaced. Checking with an ohmmeter is okay for testing a completely opened or shorted coil, but for coil voltage output, next to worthless.


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## Poje (Aug 2, 2012)

NickD said:


> With a conventional 60 Hz transformer with 120VAC applied, if you want say 1,200 VAC on the secondary winding, use approximately ten times the coil turns in the secondary.
> 
> Ignition coils don't work this way, pulsed with a DC current that switches off instantly producing an extremely rapid collapsing magnetic field. Even with only a ten turn, turn ratio, in theory can hit an infinite number of volts output. Only limit is when the spark plug fires, dictating why the lowest possible gap should be used.
> 
> ...


Thx!

I sent a Scan to Brian at Vermont Tuning, we'll see what he says.


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## cruzeman48 (Aug 18, 2013)

Hey Poje,
Does it seem that the car runs / idles worse when it gets warmed up? I'm having similar problems.


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## Poje (Aug 2, 2012)

cruzeman48 said:


> Hey Poje,
> Does it seem that the car runs / idles worse when it gets warmed up? I'm having similar problems.


No the idle is steady, its when i ask for Torque.

Gonna wait for Brian's response and see.


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## XtremeRevolution (Jan 19, 2012)

Did you check the resistors and springs yet? It's seriously only 5 minutes to check and put it all back together.


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## NickD (Dec 10, 2011)

Stretch my four springs out so they stick out about an eight of inch beyond the boot. Tip the coil module toward me so I can see all four making contact with the spark plug tips. With mild pressure swing it vertically then push it down. This way I know all four springs are making good contact.


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## Poje (Aug 2, 2012)

XtremeRevolution said:


> Did you check the resistors and springs yet? It's seriously only 5 minutes to check and put it all back together.


Ya, i said i went back to my Mecanic and we checked, everything install wise and condition wise from the outside was good.


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## Poje (Aug 2, 2012)

I just saw in another Thread that higher boost and other factors increase the Voltage at witch the Coil pack function and that it put more stress on it.

Anyway, gonna see what Brian says.


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## ChevyGuy (Dec 13, 2014)

Poje said:


> I just saw in another Thread that higher boost and other factors increase the Voltage at witch the Coil pack function and that it put more stress on it.


Correct. Also, a wider spark gap. Let your plugs go too long and it can stress the coil and increase the chance of a flash over that damages the coil.


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## GRIMland (Jun 1, 2014)

My Mom's 2010 Corolla had one coil pack go at about 50k. It's a 5 speed manual and when coming to a complete stop it would idle rough for a moment right when it stopped moving, with rpm drop, but would only last about a second, then would stabilize. Eventually it gave a check engine light at about 60k while on the interstate (was still running fine otherwise) and she had it fixed under warranty (extended).

Now her car has over 70k and it's happening again - I assume a different cylinder's coil pack.


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## Poje (Aug 2, 2012)

It was the Coil-pack finaly, changed it and everything is back to normal!


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