2007 xc90 3.2L melted ignition coil

dkellogg3 · Post by **dkellogg3** » 16 Apr 2014, 22:11

Hey all.

2007 xc90 3.2
19#,### miles

Got a call from the wife on her way home today. "Engine is running really rough and check engine light is blinking. Can only 30 mph."

I got home and threw my ELM/Torque on the OBD and found 2 codes P0302 and P0352. Misfire Cylinder #2 and Ignition coil "B" (#2). Pulled coil #2 and found this:

(hmmm... can't get the image to work... here's he link: https://www.flickr.com/photos/dkellogg3/13907689054/)

along with a little bit of oil in the plug well.

Questions for you wise folk...
1) being that the coil is melted through... is there oil *inside* the coil that's leaked out, or is that engine oil.

2) I need this car back on the road tomorrow night. if I find no local source for the Denso coil, is it okay to use a NAPA one?

TIA!
Don

dkellogg3 · Post by **dkellogg3** » 16 Apr 2014, 22:52

just a little further info... the oil is very thick and sticky; way thicker than molasses. and stinky, too. leads me to believe this is not an active valve cover gasket issue.

Post by **jimmy57** » 17 Apr 2014, 08:53

I have never seen a 3.2 coil fail. Interesting.
Oil is used in some coils.
The coils have an amplifier circuit and that circuit could have failed and caused the coil to overheat and melt like yours. It could also have a continuous signal from ECM that failed it. Too wide spark plug gap also places greater load on coil.
When you replace coil if it runs fine then no worries.
If it still misses then do not run it long or even leave key on without disconnecting that coil. The wiring to coil needs to be inspected.

dkellogg3 · Post by **dkellogg3** » 17 Apr 2014, 19:07

Interesting you mention gap. Plus are old and will be replaced now too. What's the required gap?

Post by **jimmy57** » 17 Apr 2014, 19:30

My recollection is 1.0 mm/.040 inch.

Post by **abscate** » 18 Apr 2014, 15:38

That's not engine oil. It's probably melted plastic of some kind. A new coil (maybe do all of them?) will get you back on the road, Shirley

phantom1 · Post by **phantom1** » 08 Sep 2016, 08:16

I just had the same situation happen to my '07 Volvo xc90 yesterday. Wife was driving it home, check engine light began to blink then the "slow down/ shift up" warning came on. She was able to get it home but when she went to start it again, the engine cranked over but didn't fire up. I could smell some burning plastic/ rubber when I tried to start it. I lifted the hood and noticed cylinder#2 was melted which clearly was unlike any other cylinder. When you replaced your cyclinder coil, was everything ok? Just wondering what may have made this one coil melt?

Post by **jimmy57** » 08 Sep 2016, 12:01

I have now seen coils on other makes and other coil manufacturers do that same thing. On many it looks like a plastic volcano eruption.
It is likely a transistor that burns and leaves continual coil current flow at a higher current. The circuit in coil is tasked with regulating current to coil. If voltage gets lower then transistor will increase current (wattage for adequate spark is more or less fixed. Volts X Amps = Watts. IF V falls then A is increased to keep the product, W, the same). If the transistor circuit failed shorted then it would overheat coil and plastic filler would get molten and leak.