Testing coil packs?

[SVX8588]

So, my car started missing badly on sunday. I narrowed it down to the middle cylinder on the passenger side. I'm guessing it's the coil but it could also be the injector I suppose. Is there any way to test the coil before spending $80 or more on a new one?

I think I'll try listening to the injector to make sure it's clicking. Just the same, if I can be sure that the coil is bad before ordering a new one it would make me feel a lot better.

[1986nate]

Pull the coil and inspect for cracks. If it's arcing, it will also show signs of being "burnt".

[dannmarr]

How did you narrow it down? What test have you done? Do you have codes?

[SVX8588]

I don't see any burn marks, but there is a crack along the raised part (see pic).
The boot looks fine.

http://www.subaru-svx.net/forum/attachment.php?attachmentid=16795&stc=1&d=1351306146

I narrowed it down by pulling the plug on each injector one at a time. The one that didn't make a difference is the one that I'm assuming has a bad coil. But like I said before, it could also be the injector somehow. I'm planning to listen to the injectors tomorrow and see if they all make clicking noises.
I don't have a CEL, but I didn't check for hidden codes either.

Thanks for the help!

[dannmarr]

My bad coil looked just like that. You could hear it clicking (shorting to the engine from the crack). Try switching the coil with another and see if the problem follows.

[SVX8588]

Ok, swapped it with the center coil on the driver side and the problem followed. Just ordered a new one now. Thanks for the coupon! :)

[steveherman]

What coupon do u speak of?
How much was one?

[SVX8588]

Coupon: http://www.subaru-svx.net/forum/showthread.php?t=60170

The coil was $70 something before the coupon and $67 with the coupon.

[EdWindows]

I have a misfire on my engine too (same exact cylinder, oddly enough), and I've tried to remove it to test it but I can't unclip the connector from the bracket that holds all 3 connectors. :confused:
Is there a trick to getting it off?

Sorry if I'm hijacking the thread, but I felt that it's too small an issue for its own thread.

[SVX8588]

Yes it is quite tricky. It took me probably 20 mins to get it off the first time. I took a small flat screwdriver and used it to pry the small flat plastic tab toward the body of the connector. If the metal tab that it slides onto is at all rusty it makes it much more difficult to get off. I'd take a picture for you, but it's rainy and windy outside!

Let me know if you can't figure it out and I can take a picture when the hurricane slows down a little!

Welcome to SVXWN, by the way :)

[svxfiles]

I have a misfire on my engine too (same exact cylinder, oddly enough), and I've tried to remove it to test it but I can't unclip the connector from the bracket that holds all 3 connectors. :confused:
Is there a trick to getting it off?

Sorry if I'm hijacking the thread, but I felt that it's too small an issue for its own thread.

Once you have a new coil in hand its easier to see how to remove the original.

[EdWindows]

Yes it is quite tricky. It took me probably 20 mins to get it off the first time. I took a small flat screwdriver and used it to pry the small flat plastic tab toward the body of the connector. If the metal tab that it slides onto is at all rusty it makes it much more difficult to get off. I'd take a picture for you, but it's rainy and windy outside!

Let me know if you can't figure it out and I can take a picture when the hurricane slows down a little!

Welcome to SVXWN, by the way :)

Thanks!
It took me a few minutes to figure out the plastic tab part. The metal tab is what I'm having trouble with. Does it really just slide on and off? It's really on there and I don't wanna apply brute force and risk breaking something. :eek:
I also heard that hurricane has some crazy flooding. A classmate of mine showed me a picture of a shark swimming between all the stuck cars! :eek:
Stay safe!

Once you have a new coil in hand its easier to see how to remove the original.

That's the thing: I want to make sure it's the coil before I drop $80 on a new one. :lol:

[svxfiles]

Thanks!
It took me a few minutes to figure out the plastic tab part. The metal tab is what I'm having trouble with. Does it really just slide on and off? It's really on there and I don't wanna apply brute force and risk breaking something. :eek:
I also heard that hurricane has some crazy flooding. A classmate of mine showed me a picture of a shark swimming between all the stuck cars! :eek:
Stay safe!



That's the thing: I want to make sure it's the coil before I drop $80 on a new one. :lol:

That was Alan from The Burg......
You know, Landshark!:lol:

[SVX8588]

Thanks!
It took me a few minutes to figure out the plastic tab part. The metal tab is what I'm having trouble with. Does it really just slide on and off? It's really on there and I don't wanna apply brute force and risk breaking something. :eek:
I also heard that hurricane has some crazy flooding. A classmate of mine showed me a picture of a shark swimming between all the stuck cars! :eek:
Stay safe!



There is a plastic tab that secures the connector to the metal tab. Different than the one that secures the two pieces of the connector together.
Thankfully the hurricane hasn't been bad here. A little rain and some wind. Not near as bad as they were saying.

[EdWindows]

There is a plastic tab that secures the connector to the metal tab. Different than the one that secures the two pieces of the connector together.
Thankfully the hurricane hasn't been bad here. A little rain and some wind. Not near as bad as they were saying.

OH ok. I'll try to pry it with a screwdriver then.:)

[immortal_suby]

Dumb question but I don't know the answer - can you unplug the coils with the motor running or will you be shocked?

[oab_au]

Dumb question but I don't know the answer - can you unplug the coils with the motor running or will you be shocked?

No, there is only 12Volts DC on the coil wires.

Harvey.

[SVX8588]

Dumb question but I don't know the answer - can you unplug the coils with the motor running or will you be shocked?

If you can get to the connectors! I can't get my hands down there with the airbox on. It's a whole lot easier to just unplug injectors, IMO.

[EdWindows]

That was Alan from The Burg......
You know, Landshark!:lol:

I found a picture of the shark.
http://sphotos-a.xx.fbcdn.net/hphotos-ash3/545553_367971766620612_481583034_n.jpg

[dannmarr]

If you can get to the connectors! I can't get my hands down there with the airbox on. It's a whole lot easier to just unplug injectors, IMO.

Ive seen this mentioned before. Can someone explain how unplugging the injectors help test if the coils are bad? I have an idea, but an explaination with steps would be helpful. Thanks:)

[EdWindows]

Ive seen this mentioned before. Can someone explain how unplugging the injectors help test if the coils are bad? I have an idea, but an explaination with steps would be helpful. Thanks:)

Well, if you have no spark to ignite the fuel, then unplugging the injector does nothing to the engine.
When you unplug an injector on a cylinder with a working coil, the engine bogs and starts missing, so you know that's not the cylinder with the bad coil. :p

[svxfiles]

Well, if you have no spark to ignite the fuel, then unplugging the injector does nothing to the engine.
When you unplug an injector on a cylinder with a working coil, the engine bogs and starts missing, so you know that's not the cylinder with the bad coil. :p

This is correct,
but if you have a weak coil/spark then the engine will miss with the fuel injector disconnected,
but can still have a bad coil.

[dragoontwo]

Ive seen this mentioned before. Can someone explain how unplugging the injectors help test if the coils are bad? I have an idea, but an explaination with steps would be helpful. Thanks:)

If there is no spark to a cylinder, unplugging the injector will yeild no change in the engine performance at idle. For instance if you unplug an injector for a cylinder that has spark, the engine will run noticably rougher at idle.

[theflystyle]

i wish i had taken a picture of the coil pack when tom was changing the plugs last weekend. his exact words "i have never seen a coil look like that before"

[Sean486]

One of mine went bad, but looked just fine.

[dannmarr]

This is correct,
but if you have a weak coil/spark then the engine will miss with the fuel injector disconnected,
but can still have a bad coil.

Thanks, this was my issue. Sometimes it's a good idea to physically look at the coil for cracks. Thanks for all the responses!:)