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1991 Legacy coil problem?


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11 replies to this topic

#1 jwk

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Posted 30 December 2003 - 12:42 PM

Hi,

This is my first post here. I searched the forum and couldn't find an answer, so I have a question for the group. Yesterday morning I drove my 1991 Subaru Legacy to work, and it ran fine. I drove it at lunch, and it also ran fine. After work, I started it up, and it seemed to be missing a cylinder, running and idling roughly. I limped it home, and this morning began investigating the problem. I started it up, pulled the spark plug wires from the coils one by one, then plugged them back in. Each time, a spark would jump from the coil to the wire, and the engine would run even worse (on 2 cylinders), until I tried the last one (driver's-side front). When I pulled this one, there was no change in the (rough) idle, and no spark jumping across to the wire. At this point I noticed that a spark was jumping across from the body of the coil to the metal bracket in front of the coil, on the front toward the right side.

Do I have a bad coil, or could it be some other problem? Can a coil go bad on just one side? I checked on coil prices, and they're expensive, so before I bought one, I wanted to check with everyone to see if the consensus is that the problem is a coil gone bad. Also, if it is the coil, would it be bad for me to get one from a salvage yard?

Thanks and regards,
JWK

#2 Legacy777

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Posted 30 December 2003 - 02:11 PM

these coils typically can't go bad on one side.

I'd check the plugs & wires first. May want to just replace them. If you still have problems, I'd probably say it's the coil.

I think I got mine for around $60 bucks from www.libertysubaru.com

#3 Supaglu

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Posted 30 December 2003 - 03:43 PM

Hi,
Swap over the two plug wires on that side and see if the misfire swaps cylinders, sounds to me like you have a bad plug "wire".

Regards
Dave H

#4 Warp3

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Posted 30 December 2003 - 04:15 PM

My 99 2.5RS was doing the EXACT same thing about 2 years ago and it was a bad plug wire at fault, so I'd try that first. Make sure you don't have a crack in the insulator portion of the terminal on the coilpack, though...if you do, you may need a new coilpack as well. But regardless, I'd change the wires first.

#5 jwk

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Posted 31 December 2003 - 11:25 PM

I switched the plug wires, and it definitely was the problem. Thanks very much for all the replies and help.

JWK

#6 jwk

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Posted 01 January 2004 - 10:28 PM

Another question: I put in a new set of wires today, and couldn't get the boots to go down far enough to 'snap' into the shields surrounding the head. The old plugs were far enough in so that a groove surrounding the spark plug end of the wire was sort of snapped in place. Is there an easy way to accomplish this?

Thanks

#7 DerFahrer

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Posted 02 January 2004 - 01:26 AM

So you're saying that the rubber boot on the plug side is too long to allow the connectors to make contact?

Are you sure you have the right wires?

#8 jwk

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Posted 02 January 2004 - 10:48 AM

Originally posted by subyluvr2212
So you're saying that the rubber boot on the plug side is too long to allow the connectors to make contact?

Are you sure you have the right wires?


The new wires look identical to the old ones. The connectors click on to the plugs, but I can't get the groove on the outside of the boot down far enough to snap into the heat shield. It comes close, but I just can't get it down far enough. It might just be my technique. Does this make any sense?

#9 jwk

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Posted 06 January 2004 - 11:24 AM

Now I'm not so sure it was the wires. After I installed a new set of wires, there's still a spark jumping out of the side of the coil (toward the front of the car). I stuck a piece of plastic between the coil and the bracket on the front, and the car started running fine. Coils aren't supposed to produce sparks anywhere but where the wire plugs in, right? I think mine might be cracked on the side.

Will a '95 Legacy coil pack work on my '91 automatic Legacy? I have access to a used one.

#10 Legacy777

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Posted 06 January 2004 - 01:16 PM

Yeah it will.

There are two different coils. The MT had the "diamond" coil packs, and the autos had the hitachi coil packs. The 95's I believe all had the diamond coil pack, and yes you can stick a diamond coil pack on a car that originally had a hitachi. I did it.

The diamond coil packs are supposedly able to handle a little more juice, which is why I upgraded when I put my MSD dis 2 ignition in.

#11 jwk

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Posted 06 January 2004 - 01:50 PM

That's great news. I'll report back as soon as I've tried it out, probably this weekend. Thanks for the info!

James

#12 Alaska Brat

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Posted 17 June 2004 - 10:30 PM

Now I'm not so sure it was the wires. After I installed a new set of wires, there's still a spark jumping out of the side of the coil (toward the front of the car). I stuck a piece of plastic between the coil and the bracket on the front, and the car started running fine. Coils aren't supposed to produce sparks anywhere but where the wire plugs in, right? I think mine might be cracked on the side.

Will a '95 Legacy coil pack work on my '91 automatic Legacy? I have access to a use
d one.

Path of least resistance. The spark goes from the coil through the wire, through the plug, jumps the gap, goes through the block, jumps the gap on the opposite plug, through the wire, back to the coil. Fires both plugs at once. Its a waste spark system. If both wires and both plugs are good, the coil has to be bad. I have very seldom seen that happen. Karen Boston




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