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#185264 - 01/31/06 04:33 PM bad coil???
Atl_Monte Offline
Member

Registered: 08/16/04
Posts: 1372
Loc: Atlanta, GA
How can you tell if your ignition coil is going bad? I have an Accel super coil.
_________________________
1988 Monte Carlo SS fully customizedm, cowl hood, Kandy paint w/ ghost flames, power sunroof, 24" rims 327 SB - SOLD

1986 Monte Carlo SS 350 create motor, cowl hood, shaved handles & trunk, power sun roof, digital dash
http://youtu.be/aKZI0FhUP6U

1984 H/O Cutlass lightning rods 8.5" rear LT1 and C5 brake conversion under way 24" rims

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#185265 - 01/31/06 04:45 PM Re: bad coil???
Eric G Offline
Member

Registered: 07/09/05
Posts: 393
Loc: Columbus,Oh
one of your plug wires off and stick a screwdriver in it and put the other metal part of the screwdriver on a metal patr of the body of the car and crank your car and it will arc over if you c it if you dont its bad.
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Yep thats me getting in on driver side gonna burn sum rubber!

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#185266 - 01/31/06 05:03 PM Re: bad coil???
Atl_Monte Offline
Member

Registered: 08/16/04
Posts: 1372
Loc: Atlanta, GA
I know its not bad yet because the car still runs but trying to see if its going out, because under a load its seems like the ignition system isn't cutting it...
_________________________
1988 Monte Carlo SS fully customizedm, cowl hood, Kandy paint w/ ghost flames, power sunroof, 24" rims 327 SB - SOLD

1986 Monte Carlo SS 350 create motor, cowl hood, shaved handles & trunk, power sun roof, digital dash
http://youtu.be/aKZI0FhUP6U

1984 H/O Cutlass lightning rods 8.5" rear LT1 and C5 brake conversion under way 24" rims

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#185267 - 01/31/06 10:03 PM Re: bad coil???
DLV555 Offline
10+ Year
Member

Registered: 01/22/01
Posts: 2119
Loc: Rochester, NY USA
How can you tell it is the ignition system that is failing under load? What is the car doing?
_________________________
1987 Monte Carlo SS, 400SBC, Edelbrock Intake, mild Lunati Voodoo cam, Flowtech LT headers, 2.5" true dual exhaust, Delta-Flow 40s
1993 Buck Roadmaster, all stock grandma car DD
1991 GMC Sierra 1500 LWB, 355 w/ edelbrock cam, Pacesetter headers, thrush welded muffler w/ dual outlet
1973 Mercury Montego MX 351C
1987 Monte Carlo SS(RIP 11/17/2001)

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#185268 - 01/31/06 11:13 PM Re: bad coil???
baaboo Offline
Member

Registered: 07/24/09
Posts: 8604
Loc: Racine, WI
I think that a weak coil would actually work like a rev limiter, right? The spark wouldn't go any higher, and the engine would just peak out.
_________________________
1987 Aerocoupe, 383 Super Ram and 20-gallon custom aluminum tank. Car retired (for now) from open road racing, but I'm not.

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#185269 - 01/31/06 11:31 PM Re: bad coil???
RaGG Offline
Member

Registered: 02/10/02
Posts: 340
Loc: Memphis, TN
If you have a multimeter, or just an adjustable ohm-meter, check the resistance between the bottom terminal, (where the spring/bushing touches), and the wire on the coil that goes to the tach. And check the resistance between the bottom terminal and the put the other lead on the ground wire, or the iron core if there is no ground wire.

Use the highest scale, the resistance for the tach-bottom terminal should have a measurable resistance value between 6000-30K ohms.

My experience with bad coils is either they work or don't, or throttle response just goes noticably down the drain.

Mallory in cap coil has been on my car for like 2 years. Works great up to 6K on my mild 383.

A way i test em sometimes is to take a spare spark plug, and disconnect 1 plug wire on the engine and snap the spare plug in the plug wire youj unplugged, ground the spark plug on something and fire up the engine. Weak spark usually delivers a orange/yellow spark.....strong spark is blue/white (i always buy 9, incase i crack one wrestling between the headers,....down to an art now tho)
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gas guzzler

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#185270 - 02/01/06 06:17 AM Re: bad coil???
Atl_Monte Offline
Member

Registered: 08/16/04
Posts: 1372
Loc: Atlanta, GA
Quote:
Originally posted by DLV555:
How can you tell it is the ignition system that is failing under load? What is the car doing?
it keeps doing this pinging-popping sound out the tail pipe...doesn't really do it that much at an idle like once every minute or so, but is a lot more constant in drive and if you try to put the pedal down the engine goes posh(thru the carb) and bogs down almost cutting off....
_________________________
1988 Monte Carlo SS fully customizedm, cowl hood, Kandy paint w/ ghost flames, power sunroof, 24" rims 327 SB - SOLD

1986 Monte Carlo SS 350 create motor, cowl hood, shaved handles & trunk, power sun roof, digital dash
http://youtu.be/aKZI0FhUP6U

1984 H/O Cutlass lightning rods 8.5" rear LT1 and C5 brake conversion under way 24" rims

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#185271 - 02/01/06 07:40 AM Re: bad coil???
DLV555 Offline
10+ Year
Member

Registered: 01/22/01
Posts: 2119
Loc: Rochester, NY USA
So what made you suspect the ignition system? That sounds like a timing problem or an exhaust leak or something.
_________________________
1987 Monte Carlo SS, 400SBC, Edelbrock Intake, mild Lunati Voodoo cam, Flowtech LT headers, 2.5" true dual exhaust, Delta-Flow 40s
1993 Buck Roadmaster, all stock grandma car DD
1991 GMC Sierra 1500 LWB, 355 w/ edelbrock cam, Pacesetter headers, thrush welded muffler w/ dual outlet
1973 Mercury Montego MX 351C
1987 Monte Carlo SS(RIP 11/17/2001)

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#185272 - 02/01/06 10:16 AM Re: bad coil???
RaGG Offline
Member

Registered: 02/10/02
Posts: 340
Loc: Memphis, TN
Sound like its runnign real LEAN. Had that problem before.

Had poping at idle and backfires through carb on hard acceleration. Had to step up the jets approx 2 past stock, which is wasn't at. And baseline the idle mixture screws to out 2 turns evenely on each side. (holley)

What carb?
If its a result of WAY to high timing, usually a rev in park will deliver the backfire through carb, but under load is where the lean condition will shine.
_________________________
gas guzzler

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#185273 - 02/01/06 01:45 PM Re: bad coil???
MrsDzSS Offline
Member

Registered: 01/01/06
Posts: 260
Loc: Flagstaff AZ
Hit up one of the tools trucks and buy a ST-125 spark tester for HEI.You can put the tester inline with one spark plug, start the car tach it up or load it and watch the spark on the tester.The tester takes 28kv to jump....if the coil is weak you will see the spark go way

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#185274 - 02/01/06 11:49 PM Re: bad coil???
Atl_Monte Offline
Member

Registered: 08/16/04
Posts: 1372
Loc: Atlanta, GA
Quote:
Originally posted by DLV555:
So what made you suspect the ignition system? That sounds like a timing problem or an exhaust leak or something.
I started to suspect the ignition because this problem just started like out of no where one day it wasn't doing it the next day it is, wasn't like I was playing with the timing and got it out of wack...so I'm thinking something is failing....
_________________________
1988 Monte Carlo SS fully customizedm, cowl hood, Kandy paint w/ ghost flames, power sunroof, 24" rims 327 SB - SOLD

1986 Monte Carlo SS 350 create motor, cowl hood, shaved handles & trunk, power sun roof, digital dash
http://youtu.be/aKZI0FhUP6U

1984 H/O Cutlass lightning rods 8.5" rear LT1 and C5 brake conversion under way 24" rims

Top
#185275 - 02/02/06 09:01 AM Re: bad coil???
DLV555 Offline
10+ Year
Member

Registered: 01/22/01
Posts: 2119
Loc: Rochester, NY USA
Okay, I see what you mean. Your description doesn't sound like a bad ignition system though. How many miles are on the engine? When I mentioned timing I menat it could be your timing chain getting stretched out. My '73 Montego exhibited similar symptoms when that happened, though it was pretty severe. and my SS had an exhaust leak problem. In the case of the timing chain obviously the spark was happening jumping around as far as timing and actually igniting the fuel with the intake valve open at times, so it cause that pop you mention. In the case of an exhaust leak it got so bad that scavenging was pretty much not happening in one cylinder, so instead of leaving the cylinder the exhaust gas would ignite the incoming air/fuel charge and pop back up the carb. Both of those were pretty sever like I mentioned once they advanced to those stages the cars were pretty hard to drive. Sorry, I just wanted to give you my line of reasoning. Can a bad coil cause symptoms like you describe? I'd hate to see you buy an expensive aftermarket coil if the old one is still good.
_________________________
1987 Monte Carlo SS, 400SBC, Edelbrock Intake, mild Lunati Voodoo cam, Flowtech LT headers, 2.5" true dual exhaust, Delta-Flow 40s
1993 Buck Roadmaster, all stock grandma car DD
1991 GMC Sierra 1500 LWB, 355 w/ edelbrock cam, Pacesetter headers, thrush welded muffler w/ dual outlet
1973 Mercury Montego MX 351C
1987 Monte Carlo SS(RIP 11/17/2001)

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#185276 - 02/02/06 09:37 AM Re: bad coil???
MC87SS Offline

Moderator
Member

Registered: 03/16/05
Posts: 5881
Loc: Tallahassee, Florida
Does it happen more in damp conditions?
I have the same problem with my MSD 6A box & Pro Billet dist.
If i pull the cap and dry it the problem goes away.
Every time i wash the engine compartment or it rains this happens.

Pop the cap and see if the terminals look like they have been burnt.
Another trick is to lightly mist the engine with a spray bottle at night with the engine running and see if you see any sparks between the wires.
HTH
_________________________

87 Monte SS / Black-Saddle T-Tops
85 Monte SS / Black-Gray T-Tops (Wifes Car)
SMCC Florida Chapter


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#185277 - 02/02/06 10:30 AM Re: bad coil???
DLV555 Offline
10+ Year
Member

Registered: 01/22/01
Posts: 2119
Loc: Rochester, NY USA
Quote:
Originally posted by MC87SS:
Pop the cap and see if the terminals look like they have been burnt.
Another trick is to lightly mist the engine with a spray bottle at night with the engine running and see if you see any sparks between the wires.
HTH
_________________________
1987 Monte Carlo SS, 400SBC, Edelbrock Intake, mild Lunati Voodoo cam, Flowtech LT headers, 2.5" true dual exhaust, Delta-Flow 40s
1993 Buck Roadmaster, all stock grandma car DD
1991 GMC Sierra 1500 LWB, 355 w/ edelbrock cam, Pacesetter headers, thrush welded muffler w/ dual outlet
1973 Mercury Montego MX 351C
1987 Monte Carlo SS(RIP 11/17/2001)

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