I've been advised a lot to replace ignition wires, cup and rotor. I bought parts online and replaced: ignition wires and cup (BOSH) and rotor (Japan). Works great - performs better. But I have questions. Why the wires need to be replaced? Plugs,rotor,cup - I understand, they get worn,but my old Prestolite wires did not have any visible signs of damage or rust described in Haynes manual. They look even better than my new ones! And I wonder -it's simply wires-how are some brands better than others and how do they wear out? How do wires affect fuel economy?
Thanks in advance!
I've been advised a lot to replace ignition wires, cup and rotor. I bought parts online and replaced: ignition wires and cup (BOSH) and rotor (Japan). Works great - performs better. But I have questions. Why the wires need to be replaced? Plugs,rotor,cup - I understand, they get worn,but my old Prestolite wires did not have any visible signs of damage or rust described in Haynes manual. They look even better than my new ones! And I wonder -it's simply wires-how are some brands better than others and how do they wear out? How do wires affect fuel economy?
Thanks in advance!
The insulation on the wires can breakdowns over time, not necessarily from rubbing against anything. Once this happens you'll lose some high voltage going to the spark plugs, which fouls them up. Then the car will start getting poor milage. If you look at a $30 per of wires compared to $75+ pair you will see the difference on how they are assembled.
If they are in good physical shape and ohms out within specs you don't really have to replace them. Many people opt to replace anyway out of common practice and because most manufacturers have it as a service item. I won't go into details of all that can go bad in the wires but will mention two.
Many ignition wires have added resistance in it's wiring that can go bad over time. Carbon ignition wires, just like carbon film resistors, will change resistance over time due to the carbon molecules breaking down. The biggest change will occur when it is first put into service. But eventually, and somewhat similar in behavior to engine oil breakdown, the carbon molecules in the wire will "settle in" during some break-in period and then it will hold it's resistance for quite some time.
The high voltage potential inside the ignition wire, together with high engine temperature, will cause the wire insulation to break down over time. This causes high static buildup which attracts dirt particles. The accumulation of this will create a leak point for arcing to occur. One thing you can do to hold back arcing is to, clean the entire insulation jacket with Simple Green degreaser, dry it out, then apply silicone lubricate.
So yes, you can prolong the use of ignition wires, and no, they don't last forever.
Finally, get the costlier NGK wires if they are going to replace them.
Thank you so much.
I've had trouble getting NGK wires. I guess I did a good choice with Bosh in Autozone for $50. They have lifetime replacement warranty. My previous Prestolite wires have cup boots sealed with silicone where it contacts with wire. Do you think I have to put some silicone on the wire?
Thank you so much.
I've had trouble getting NGK wires. I guess I did a good choice with Bosh in Autozone for $50. They have lifetime replacement warranty. My previous Prestolite wires have cup boots sealed with silicone where it contacts with wire. Do you think I have to put some silicone on the wire?
Definitely use some silicone on the wire around the rubber boot that goes over the spark plug hose. Those Bosch wires are known to lift out of the spark plug and cause the engine to misfire and have poor acceleration. It happened to me and a great number of people. So beware of this if your engine all of a sudden starts missing.
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