i can see the spark plugs fire
08-10-2004, 05:50 PM
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i can see the spark plugs fire Hey i'm not sure if this is the right section or not but i'll post here anyway. I had my car running the other day and i popped the hood. It was pitch dark out and i could see atleast 2 of my plugs like glowing/firing with the ignition. The porcelain part of the plug that is exposed( the rest is in the head and wire)The plugs and wires are tight and as far as i know the wires are good. What would make you able to see the plugs firing. I am suspecting a loose contact from the wire around the plug..? Do you think thats whats causing it? I guess its arcing but why? How much power could i be losing. The car seems to be running fine but if i'm losing bpower.. Any othetr suggestions. What should i do
08-12-2004, 07:46 AM
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Spark plug wires are made of a conductive core and typically silicone rubber insulation. The core is usually a carbon impregnated fiber or wire. The conducting core is bent over at the wire end and the boot metal is crimped over the core/insulation of the wire. Many aftermarket wires come with no boots, which allows one to add the boots of choice and cut the wires to the desired length.
Most OEM wires use a carbon fiber as this produces minimal RF noise. The down side of carbon fibers is high resistance and thus reduced spark energy. Solid wires have very low resistance, but typically produce unacceptable amounts of RF interference, frequently causing interference in radios (in the installed vehicle as well as nearby radios). This interference can also produce problems with any electronic equipment used inside the car such as fuel injection, panel meters and ABS systems. Spectral output from ignition wires can be anywhere from 10kHz to over 10GHz. Some wires use a solid metal core that is helically wound to cause the wire to look inductive at high frequencies and minimize EM radiation.
Silicones have a resistivity of 10^9 to 10^11 ohms per meter (between 1 and 100M ohms per mm). Given a core diameter of 2mm and insulation diameter of 7mm that's only 2.5mm of insulation from the core to the outside world and most wires actually leak a considerable amount of energy to their outer shell.
If the surface of the wires becomes contaminated, it can bleed a significant amount of power out of the wire to ground at any point it touches metal or a grounded surface. One way to check for this is to view the engine compartment in total darkness. Corona discharges will be seen at any larger bleed off points. No visible coronas are not a guarantee of no leakage however. If possible, it is best to keep the wires from touching any metal or coolant hoses (coolant is highly conductive with respect to air or silicone).
I.E. it may be time to replace your wires (or at least 2 of them)...
Most OEM wires use a carbon fiber as this produces minimal RF noise. The down side of carbon fibers is high resistance and thus reduced spark energy. Solid wires have very low resistance, but typically produce unacceptable amounts of RF interference, frequently causing interference in radios (in the installed vehicle as well as nearby radios). This interference can also produce problems with any electronic equipment used inside the car such as fuel injection, panel meters and ABS systems. Spectral output from ignition wires can be anywhere from 10kHz to over 10GHz. Some wires use a solid metal core that is helically wound to cause the wire to look inductive at high frequencies and minimize EM radiation.
Silicones have a resistivity of 10^9 to 10^11 ohms per meter (between 1 and 100M ohms per mm). Given a core diameter of 2mm and insulation diameter of 7mm that's only 2.5mm of insulation from the core to the outside world and most wires actually leak a considerable amount of energy to their outer shell.
If the surface of the wires becomes contaminated, it can bleed a significant amount of power out of the wire to ground at any point it touches metal or a grounded surface. One way to check for this is to view the engine compartment in total darkness. Corona discharges will be seen at any larger bleed off points. No visible coronas are not a guarantee of no leakage however. If possible, it is best to keep the wires from touching any metal or coolant hoses (coolant is highly conductive with respect to air or silicone).
I.E. it may be time to replace your wires (or at least 2 of them)...
08-12-2004, 06:58 PM
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