Coil testing ?

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Dec 14, 2014 | 08:09 AM

Fuelie Dave

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Instructor

Joined: Sep 2008

Posts: 179

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From: Blue Springs Missouri

Coil testing ?

What is an accepted method of testing a used coil to determine if it is good? The coil is not attached to the car, has no broken terminals and appears to have all of its internal oil. Thanks for your input.

Dave

Dec 14, 2014 | 10:46 AM

Velox

Drifting

Joined: Sep 1999

Posts: 1,417

Likes: 161

From: Des Moines, Iowa, USA Iowa

Quote:

Originally Posted by Fuelie Dave

What is an accepted method of testing a used coil to determine if it is good?

Using a digital multimeter set to read ohms attach test leads to + and - terminals of the coil, it should read just a few ohms, like 1 or 2 or similar, this checks the primary windings and exact value depends of what coil you are testing, also varies with TI coil vs standard coil, values are published online. Measure the secondary coil resistance by changing the + test lead to the center terminal of the coil, this will be a much higher reading, like 8000 or 10000 ohms or something, again number published online for each specific coil.

Jun 19, 2023 | 12:25 PM

Dino_'72

Pro

Joined: Aug 2000

Posts: 610

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From: Vancouver B.C.

Do you know which Petronix conversion kit you have? Different version have different voltage and coil requirements.

Jun 19, 2023 | 02:09 PM

Dave Strickland

Drifting

Joined: Jun 2001

Posts: 1,330

Likes: 321

From: Massachusetts

Coil

Quote:

Originally Posted by Fuelie Dave

Dave,
The only way to properly test an ignition coil is to put it on any running car and test drive it making sure to get things up to full running temperature. Coils may check out with a multimeter but can break down under full operating temperature.

Jun 19, 2023 | 02:52 PM

dr914

Racer

Joined: Oct 2013

Posts: 438

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From: Marietta Georgia

coils RARELY fail, if you can read 30 degrees dwell, the coil should spark. if it does not then it is bad

Jun 19, 2023 | 03:25 PM

Dan Hampton

Le Mans Master

Joined: Sep 2008

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From: Lake Minnetonka, Mn

2018 C1 of Year Finalist

Quote:

Originally Posted by dr914

coils RARELY fail, if you can read 30 degrees dwell, the coil should spark. if it does not then it is bad

Lack of spark can be attributed to factors other than a bad coil.

Jun 19, 2023 | 03:29 PM

Vega$Vette

Race Director

Joined: Apr 2005

Posts: 10,179

Likes: 2,306

From: Wesley Chapel, FL Las Vegas, NV

Quote:

Originally Posted by dr914

coils RARELY fail, if you can read 30 degrees dwell, the coil should spark. if it does not then it is bad

coils do fail. most often due to heat. running higher current then a particular coil is designed for can also cook them. like full batt to a coil designed for use with a ballast resistor. add to that the poor quality chinese coils that fail for no apparent reason.