Signs of a Bad Coil? - JeepForum.com
 
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post #1 of 8 Old 07-25-2007, 11:23 AM Thread Starter
gtospeeding
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Signs of a Bad Coil?

Is it true that the coil will either work or it wont?

what kinda symptoms does a bad coil have other than the jeep wont start?

I have a 98 4.0 with 110k

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post #2 of 8 Old 07-25-2007, 11:31 AM
Wheelin98TJ
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When mine was on its way out it was much more sensitive to moisture.

Are you having a no spark symptom?
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post #3 of 8 Old 07-25-2007, 11:35 AM
EvilM0nkey
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that's right. There usually isn't much in between. Try putting a screwdriver in one of your wires and lay the shaft near a piece of metal and have a friend try to crank it to see if you have a spark (don't touch the screwdriver unless your into that type of thing...)
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post #4 of 8 Old 07-25-2007, 11:40 AM
mdm
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A bad coil can show symptoms like loss of power after the engine/coil gets hot, high humidity, high RPMs,...
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post #5 of 8 Old 07-25-2007, 11:42 AM Thread Starter
gtospeeding
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Quote:
Originally Posted by Wheelin98TJ
When mine was on its way out it was much more sensitive to moisture.

Are you having a no spark symptom?

on cold starts the starter will crank longer before the Jeep fires. I was thinking its coil related since it looks like the coil is original

BTW --was the coil rivited or bolted to the coil bracket from the factory?
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post #6 of 8 Old 07-25-2007, 11:45 AM
mdm
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Quote:
Originally Posted by gtospeeding
on cold starts the starter will crank longer before the Jeep fires. I was thinking its coil related since it looks like the coil is original

BTW --was the coil rivited or bolted to the coil bracket from the factory?
Does the engine start OK after the initial start-up when it has been shut down for just a short time?
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post #7 of 8 Old 07-25-2007, 11:47 AM Thread Starter
gtospeeding
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Quote:
Originally Posted by mdm
Does the engine start OK after the initial start-up when it has been shut down for just a short time?
it starts better after its been running but not 100%
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post #8 of 8 Old 07-25-2007, 01:05 PM
Wheelin98TJ
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Quote:
Originally Posted by gtospeeding
on cold starts the starter will crank longer before the Jeep fires. I was thinking its coil related since it looks like the coil is original

BTW --was the coil rivited or bolted to the coil bracket from the factory?
Bolted.

IIRC, you have to unbolt the bracket first and then you can unbolt the coil.

Long crank times at cold starts is more often caused by a faulty anti-drainback valve. Its a pretty common problem with TJs.
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