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2005 chevy trailblazer_ls
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Discussion Starter · #1 ·
Is there any way to test the coil packs for the do-it-yourselfer? I just want to make sure they are putting out what they are supposed to be. Not having any probs yet, but I am ever proactive.
 

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2003 chevy trailblazer_ls
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5,268 Posts
I wonder if its just better to go on ebay and buy 1 or 2 used ones- and have them as spares.. I thinks they go for $30.
that could be an even easier 'test' for when you get one fail...
just swap them.
 

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2003 gmc envoy_slt
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I would think you would need a special piece of test equipment to get an accurate reading. Auto parts stores sell adapters to see if you are getting a spark.
 

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2002 olds bravada
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I wonder if its just better to go on ebay and buy 1 or 2 used ones- and have them as spares.. I thinks they go for $30.
that could be an even easier 'test' for when you get one fail...
just swap them.
There is a seller that has new ones for roughly around $30, and they are genuine delphi coils, BRAND SPANKIN NEW!!

I would think you would need a special piece of test equipment to get an accurate reading. Auto parts stores sell adapters to see if you are getting a spark.
if you don't have an adapter, you can also wrap copper wire around the thread of the spark plug and grown the other end of the copper wire. Just make sure it doesn't touch anything else.
 

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2003 gmc envoy_slt
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The tester I have has an adjustable air gap. The wider the gap, the more voltage being put out by the coil. But as posted earlier, I don't know how accurate it is.
 

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2005 gmc envoy_denali_xl
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Revive... Rethink...

Hi guys, know this is an old thread, but figured I didn't need to start a new title. (Unless nobody replies to this one.)

Anyhow,
I'm wondering if anyone knows a way to bench test our coils. Like at the basic level with a multi-meter. There HAS to be a set of parameters between given pins that is a known figure. Things like resistance between pin 1 and 4, 3 and the output, whatever....

I know that some shops have a bench test unit for coils that have the ability to input voltage for a measurement at output. Not to mention the 'air gap' setting where the stronger the output, the larger the gap.

I was just wondering if perhaps there's something that's quick and easy, that would at least tell if it's dead or not.

Like a lot of us here I'm sitting around doing this... :bonk: Not wanting to buy 3 coils when chasing down the dreaded "random misfire". While it first looks like it's at least on 4, I'm also suspecting 6 is acting up, and maybe even 3. Problem is, it's idling so rough that swapping a good coil to the place where there are bad ones really doesn't help that much because it'll still have a rough idle no matter where I move the dead coil(s). I'd LOVE to have 3 or 4 then put one at a time in and see how it helps. :yes:

FWIW It's got 90844 miles. Had all new plugs put in 8,000 mile ago. Thought I'd also go ahead and put all new wires in this time for $hits and giggles while I've got it turned upside down. (Well actually only the washer fluid resevoir is upside down, uh... turned on it's end that's it.)

Thanks,
DenaliDaddy :thx
 

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best way to test a cop (coil on plug) system for a bad coil is to remove the suspect coil and swap it with another in a different hole. just see if the misfire code changes position. If you have a random, try checking components that affect all holes first. (EGR valve, intake gasket, fuel pump, etc.)
 

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2003 gmc envoy_slt
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Hi, I'm new to this site and really need help, how can I tell if I have a bad coil vs a bad plug, I'm not getting a code for any cylinder misfire but my truck "sputters" at idle, I've cleaned the the throttle body and have had all the hoses checked an tightened. The codes are coming up as a bad cam or crank sensor
 

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2002 chevy trailblazer_ls
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Hi, I'm new to this site and really need help, how can I tell if I have a bad coil vs a bad plug, I'm not getting a code for any cylinder misfire but my truck "sputters" at idle, I've cleaned the the throttle body and have had all the hoses checked an tightened. The codes are coming up as a bad cam or crank sensor
I think I'd take care of the issues that are causing the codes first...The CPAS is a common repair for the 4.2...


http://forums.trailvoy.com/showthread.php?t=62398&page=5
 

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2003 chevy trailblazer_ltz
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Tired motor?

I have a 2003 LTZ. IT HAS 216,000 miles. It seems to be losing power when towing my boat/ camp trailer. The temp goes up pretty quick and seems to struggle on any incline. I replaced the clutch fan a few years ago... after driving awhile it makes the same sound it made before the clutch fan failed. Not sure if it’s just hot or what? I’m thinking on having the radiator flushed, replace spark plugs, clean throttle body, and replace fuel filter. I’ve maintained it pretty religiously since it was new. Should I replace coil packs as well? I want to feel comfortable about towing my toys over hills and going more than 40mph.
 
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