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Spark Plug Wire Resistance fb

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Old May 29, 2014 | 01:21 PM
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Gershwizzle's Avatar
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Spark Plug Wire Resistance fb

Car at hand:
1983 FB w/ stock 12a

So my car has had a stumble in the idle since I got it so I am going through the ignition system to find whats wrong, but i have a quick question.

Let me state that I just learned how to use a multimeter.

When checking the resistance of my plug wires, the FSM says they should have a resistance of around 16,000 ohms +- 40% per meter

I switch the multimeter to 20k range and am getting a reading of around 4.5 for each wire. This means the resistance is only 4500 ohms? My wires cant be much longer than 2 feet long. This means my wires are bad, correct?

Sorry if this is a dumb question..
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Old May 30, 2014 | 09:00 PM
  #2  
gerald m's Avatar
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From: Pump Handle, SK. Canada
Originally Posted by Gershwizzle
Car at hand:
1983 FB w/ stock 12a

So my car has had a stumble in the idle since I got it so I am going through the ignition system to find whats wrong, but i have a quick question.

Let me state that I just learned how to use a multimeter.

When checking the resistance of my plug wires, the FSM says they should have a resistance of around 16,000 ohms +- 40% per meter

I switch the multimeter to 20k range and am getting a reading of around 4.5 for each wire. This means the resistance is only 4500 ohms? My wires cant be much longer than 2 feet long. This means my wires are bad, correct?

Sorry if this is a dumb question..
When in doubt do yourself a favor and buy new .
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Old Jun 1, 2014 | 10:21 PM
  #3  
CrimsonPride's Avatar
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From: B'ham, AL
A low resistance reading on your wires should not cause misfire problems. And, that spec is for 3 ft. yours are 2 feet with + - 40% the readings are not that low.

Problems with spark plug wires are usually a breakdown in insulation caused by age and heat making the spark short to ground like the engine block causing a misfire or a break in the filament inside the wiring. But these types of problems should show up more under a load on the engine rather that at idle.

If your wires are old and/or your plugs, sure, replace them. But if not keep diagnosing. I know on older cars I sometimes had problems with the vacuum advance. If it's not working it won't retard the timing at idle. Just another thing to check if you already haven't.
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