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Banned
Join Date: Apr 2004
Location: Portugal
Posts: 1,513
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Testing ignition wires
I would like to test my ignition wires to make sure nothing's wrong.
What resistance should I find across them if they're ok ?? Last edited by prebordao; 11-12-2010 at 02:13 AM.. Reason: typo |
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11-12-2010, 02:13 AM
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Diss Member
Join Date: Jul 2002
Location: SC - (Aiken in the 'other' SC)
Posts: 5,020
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Different wires have different resistances. Some have high resistance and some have zero resistance by design.
Two suggestions: - Measure all the wires and any wild variance on one or two wires is rather suspect. (Note: resistance type wires: longer = more resistance) - Post the type of wires (manufacturer, part number, identifying marks, ...) to get more specific help.
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- "Speed kills! How fast do you want to go?" - anon. - "If More is better then Too Much is just right!!!" - Mad Mac Durgeloh -- Wayne - 87 Carrera coupe -> The pooch. |
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11-12-2010, 05:32 AM
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Registered
Join Date: Oct 2005
Location: Capistrano Beach, Ca.
Posts: 7,235
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Quicksilver is correct about the different wires. However, to get you started, if your wires are stock for the car listed in your signature, you should find a resistance of about 3.5-4K ohms across the wires, including the connectors. The wires themselves are very low resistance but the spark plug connector has a about a 3K ohm set of resistors inside, and the distributor cap connector is about 1K in resistance. If you are using the stock set up with the Beru connector, they are notorious for having breaks in the internal resistors which will show up as infinite resistance or wildly fluctuating readings if you shake/tap the connector during testing.
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L.J. Recovering Porsche-holic Gave up trying to stay clean Stabilized on a Pelican I.V. drip |
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11-12-2010, 06:14 AM
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Senior Member
Join Date: Feb 2000
Location: Lacey, WA. USA
Posts: 25,310
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The Bosch screw-on distributor-end connectors have a resistance of 1000 ohms. I believe the Bosch (Beru?) spark plug-end connectors have something like 3000 ohms of resistance. Or 4000. Something like that. Anyhoo........if you get consistent resistance values in the 4000-5000 range, they are working. What you're really looking for is a broken resistor. In other words......infinite resistance. If they refuse to conduct electricity, there is a problem.
Another thing to do is to run the engine in a dark garage while you watch the wires and listen. Arcing makes a snapping sound, and a small lightning bolt. Spray a fine water mist in there, and you'll see an aura. Finally, how does the engine run? If it runs smoothly, particularly at high RPM's and high cylinder pressures (throttle on), then your ignition system is doing its job.
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11-12-2010, 06:17 AM
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Banned
Join Date: Apr 2004
Location: Portugal
Posts: 1,513
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I believe my wires are stock so those guidelines suit me well.
I'm looking for this, as I have an hesitation around 2-3k rpms and I've already looked at a number of things without luck. I'm not confident that the problem lies here, but would like to rule it off... |
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11-12-2010, 07:23 AM
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