Chongo
Full Access Member
- Joined
- Aug 29, 2007
- Posts
- 255
- Reaction score
- 0
Testing plug wires
Some of you have asked me this question in the past and have asked me to post this, and I thought It could be helpful................
Testing plug wires: First of all you’ll need to buy some dielectric grease so the cables are easier to remove next time.
http://www.jamestowndistributors.com/userportal/show_product.do?pid=8196
1: Once you have removed the single cable, ( do only one at a time so you don’t loose the firing order. ) , place the ends of a ohm meter at the same time at opposite ends. Then measure the reading, it should read closely around 5,000 ohms if the value is higher than that the wires are in question. Plug wires will hold an ohm reading of around 5000 ohms for a long time, but once they begin to break down the resistance goes up quickly in carbon fiber cables.
2: A brief under hood inspection is a good way to check vacuum hoses are on and that none of them have been burned open by leaning against the exhaust manifold. You've touched every sensor connection to see if it's on tight, you've even checked for trouble codes. However, not everything calls for high-tech diagnostics and the latest scan tester. Engine misfire often is caused by leaking spark plug wires, so visual inspection could reveal what's wrong. The jackets may be damaged from the outside by abrasion caused by engine vibration (particularly at the plug-end boots), a hot engine compartment, spilled fluids or battery acid, multiple disconnections and reconnections for other service, or even a family of nesting rodents.
Run the engine in near darkness, and then look and listen. If you see little electrical arcs, or hear a snap-crack, there is high-voltage electrical leakage. Of course, running the engine at idle doesn't exercise the ignition system very hard, so you can add something to the test by spraying the plug wire ends with clean water from a household spray bottle.
Another test: With a jumper wire, ground the metal shank of a screwdriver that has a well-insulated handle. Then, run the tip of the screwdriver along the length of each wire and all around at the coil and plug boots. This will often produce an arc from the wire to the screwdriver.
Now look at the wires under good lighting. If they are damaged by abrasion, oil-soaked, cut, burned from contact with the exhaust, or have a dried-out look with heat cracks, it definitely shouldn't be a surprise if you see arcs in the dark under some conditions. However, if they look bad but there are no arcs, do a resistance check.
A conventional new plug wire has a resistance of 5,000 ohms , the wire probably is bad if the value is much higher than this. An absolutely failed wire will have a hairline break somewhere, and the resistance will be infinity.
3: Grab a water bottle sprayer and add a little regular dish soap and water and spray the spark plug wires WHILE THE ENGINE IS RUNNING in park. If the soapy water mixture finds a hole or soft spot in the spark plug wire the spark will jump out of the wire and ground itself to the water.
The engine will really miss and run bad once the spark comes out of the water. If you see the spark come out of the wire or the engine begins to run rough and miss when you spray water on the spark plug wires….you need new spark plug wires!
Watch the video……….
YouTube - How To Check For Bad Spark Plug Wires
I hope this helps…………. Chongo
Some of you have asked me this question in the past and have asked me to post this, and I thought It could be helpful................
Testing plug wires: First of all you’ll need to buy some dielectric grease so the cables are easier to remove next time.
http://www.jamestowndistributors.com/userportal/show_product.do?pid=8196
1: Once you have removed the single cable, ( do only one at a time so you don’t loose the firing order. ) , place the ends of a ohm meter at the same time at opposite ends. Then measure the reading, it should read closely around 5,000 ohms if the value is higher than that the wires are in question. Plug wires will hold an ohm reading of around 5000 ohms for a long time, but once they begin to break down the resistance goes up quickly in carbon fiber cables.
2: A brief under hood inspection is a good way to check vacuum hoses are on and that none of them have been burned open by leaning against the exhaust manifold. You've touched every sensor connection to see if it's on tight, you've even checked for trouble codes. However, not everything calls for high-tech diagnostics and the latest scan tester. Engine misfire often is caused by leaking spark plug wires, so visual inspection could reveal what's wrong. The jackets may be damaged from the outside by abrasion caused by engine vibration (particularly at the plug-end boots), a hot engine compartment, spilled fluids or battery acid, multiple disconnections and reconnections for other service, or even a family of nesting rodents.
Run the engine in near darkness, and then look and listen. If you see little electrical arcs, or hear a snap-crack, there is high-voltage electrical leakage. Of course, running the engine at idle doesn't exercise the ignition system very hard, so you can add something to the test by spraying the plug wire ends with clean water from a household spray bottle.
Another test: With a jumper wire, ground the metal shank of a screwdriver that has a well-insulated handle. Then, run the tip of the screwdriver along the length of each wire and all around at the coil and plug boots. This will often produce an arc from the wire to the screwdriver.
Now look at the wires under good lighting. If they are damaged by abrasion, oil-soaked, cut, burned from contact with the exhaust, or have a dried-out look with heat cracks, it definitely shouldn't be a surprise if you see arcs in the dark under some conditions. However, if they look bad but there are no arcs, do a resistance check.
A conventional new plug wire has a resistance of 5,000 ohms , the wire probably is bad if the value is much higher than this. An absolutely failed wire will have a hairline break somewhere, and the resistance will be infinity.
3: Grab a water bottle sprayer and add a little regular dish soap and water and spray the spark plug wires WHILE THE ENGINE IS RUNNING in park. If the soapy water mixture finds a hole or soft spot in the spark plug wire the spark will jump out of the wire and ground itself to the water.
The engine will really miss and run bad once the spark comes out of the water. If you see the spark come out of the wire or the engine begins to run rough and miss when you spray water on the spark plug wires….you need new spark plug wires!
Watch the video……….
YouTube - How To Check For Bad Spark Plug Wires
I hope this helps…………. Chongo
