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Diagnosing a bad coilpack...

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Old 03-29-2003, 02:09 AM   #1
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Default Diagnosing a bad coilpack...

What are some common "symptoms" or ways to tell if you have a bad coilpack?

Would a bad coilpack cause a cylinder to misfire on a consistent basis?

TIA
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Old 03-29-2003, 04:07 PM   #2
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Default Re: Diagnosing a bad coilpack...

Yes a completly failed coil pack will put out no spark & cause a missfire. A bad coil pack can still deliver a spark but a weaker spark that may cause a occational/intermittant missfire at diff. times.
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Old 03-29-2003, 04:28 PM   #3
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Default Re: Diagnosing a bad coilpack...

you can get a multi meter and set it to ohms i think and put it in side the coil. im not sure what the resistance should read, but you should be able to tell if it is faulty. also, i guess you could take the wire off of the plug, and hold it real close to something metal and see if it sparks. correct me if i am wrong guys. <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

<small>[ March 29, 2003, 04:33 PM: Message edited by: ArcticSS ]</small>
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Old 03-29-2003, 08:46 PM   #4
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Default Re: Diagnosing a bad coilpack...

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by wrencher:
<strong> Yes a completly failed coil pack will put out no spark & cause a missfire. A bad coil pack can still deliver a spark but a weaker spark that may cause a occational/intermittant missfire at diff. times. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Well, I'm having a constant misfire on cylinder 7, so I think that is the issue. I have brand new plug wires (Accel Extreme9000's) and I put a brand new plug in #7. I would figure a bad coilpack would be the culprit.
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Old 03-29-2003, 09:09 PM   #5
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Default Re: Diagnosing a bad coilpack...

Swap the coil packs and see if the misfire follows the coil pack. Valvegod@aol.com sells coil packs pretty cheap.
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Old 04-01-2003, 01:33 PM   #6
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Default Re: Diagnosing a bad coilpack...

Just because a coil gives you a spark in open
air doesn't mean it's good.

At the time when you're trying to make a spark
the internal cylinder pressure is roughly 10X
ambient (under load, high MAP) and the arc
voltage required is also roughly 10X what you
need to make it in free air. If you have internal
insulation breakdown, it could well be able to
produce a free-air spark but unable to spark at
maximum cylinder pressure, arcing internally
instead.

This sort of flaw will not appear to an ohmmeter
because the applied voltage is 10,000X too low
(and you couldn't affort to apply 50kV DC to the
coil anyhow).

The idea of swapping packs L/R is a straightforward
troubleshooting "cut". It will tell you for sure
if it's the pack, or not. The same applies to
plug wires, fuel injectors, anything cylinder-
specific you can exchange side-to-side until you
find something that moves the misfire.
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Old 04-01-2003, 06:56 PM   #7
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Default Re: Diagnosing a bad coilpack...

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by jimmyblue:
<strong> Just because a coil gives you a spark in open
air doesn't mean it's good.

At the time when you're trying to make a spark
the internal cylinder pressure is roughly 10X
ambient (under load, high MAP) and the arc
voltage required is also roughly 10X what you
need to make it in free air. If you have internal
insulation breakdown, it could well be able to
produce a free-air spark but unable to spark at
maximum cylinder pressure, arcing internally
instead.

This sort of flaw will not appear to an ohmmeter
because the applied voltage is 10,000X too low
(and you couldn't affort to apply 50kV DC to the
coil anyhow).

The idea of swapping packs L/R is a straightforward
troubleshooting "cut". It will tell you for sure
if it's the pack, or not. The same applies to
plug wires, fuel injectors, anything cylinder-
specific you can exchange side-to-side until you
find something that moves the misfire. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Alright thanks. Now I know hope is still alive. I'll actually switch the coilpack w/a different cylinder, then go to my local Autozone after resetting the PCM to see if I'm getting a misfire in the cylinder I switch the supposedly faulty pack to.
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Old 04-01-2003, 07:47 PM   #8
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Default Re: Diagnosing a bad coilpack...

you might want to switch the injector too, but to a different location then where you switch the coil to. especially if your relying on autozone to use thier scan tool, instead of autotap, ect where you can do it yourself.

So if the problem moves to #5 for example, then its the coil, or #3 it was the injector.

Ryan.
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Old 04-02-2003, 12:46 AM   #9
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Default Re: Diagnosing a bad coilpack...

Well, last night I pulled the wire off the plug and checked to see if I was getting spark (just for quick second), and YUP I'm definitely getting spark to cylinder #7. Now I really don't know what to do next now that I know that I am getting spark in 7 after all. <img border="0" title="" alt="[Frown]" src="gr_sad.gif" />
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Old 04-02-2003, 02:19 AM   #10
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Default Re: Diagnosing a bad coilpack...

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by slow:
<strong> you might want to switch the injector too, but to a different location then where you switch the coil to. especially if your relying on autozone to use thier scan tool, instead of autotap, ect where you can do it yourself.

So if the problem moves to #5 for example, then its the coil, or #3 it was the injector.

Ryan. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Well, I'm going to try the coilpack switch first and foremost mainly because I have no clue where to even start as far as injectors go...Never once have I seen them on the car let alone pulled them out to switch them around. <img border="0" title="" alt="[Embarrassed]" src="gr_emb.gif" />
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