Spark Plug Wire discussion

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How many miles do you run your Spark Plug Wires for? How do you know when they are bad? Is their a test for them? Anyone got brand loyalty out there? I bought an OEM motorcaft set, just because I got a good deal on them. I did some looking and the NGK set looked neat. I got 92k on the factory wires and don't really want to replace them if they are still good, just don't know if there is a way to test them. I got what seems like an intermitent miss at idle, only happens at idle, so I also am wondering if maybe it is just a motor mount that is starting to harden. I know some auto techs read these boards, so you guys would be a good source of info on wires, as you probably see these things with many miles on them on a regular basis.
 
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A complete tune up and replacement of the cap rotor wiresand proper sparkplugs etc. depending if the engine has those is well worth it.
 
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The factory service manuals usually list the resistance the wires should read at. My Honda/Acura one certainly did. I generally replace the cap and wires every 50k. Plugs I do every 25k. Most mfg spec 50k or 100k for the wires.
 
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Simply checking the resistance will only show a major glaring fault. Wires can read perfectly fine concerning their OHM readings, but have leaks and cracks through the insulation. Ford Motorcraft wires have always been superb. If yours have remained clean and dry, and you have had no spark plug problems that overloaded the system, they are probably still very good. On the other hand, at 100k, it would not hurt to get new ones. Good preventative maintenance, if not actually fixing anything. If your misfire is only at idle, it is very doubtful that your ignition is faulty. A good injector cleaner in the gas tank for one or two tanks can fix this. Gumout REGANE, or strong Chevron Techron are known good ones. Once agein, this is very good maintenance if it does not fix an actual problem. I'd do this for sure right away.
 
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i get new plug wires every 100-125k. I use OEM and have had bad luck with auto parts store plug wires. Where did you see the NGK wires? (to the original poster)
 
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Use OE wires. Have hondas and toyotas that have over 250k on original wires. Keep them shielded from contact with metal and change plugs at regular intervals. Ford wires will normally go 100-150k. Ohm checking the wires like mechtech said will only show a big problem. The only real way to check them would be on the car running with an ignition scope. If you got ford wires I would replace them, as you are getting close to 100K. If you would of got some aftermarket wires I would have said leave on what you got.
 
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About every 25-30k since they're lifetime warranty. It's overkill for sure. Plugs are done yearly on the Buick since they're easy. The Fit has coil-on-plug ignition. I'll likely pull the plugs in the spring to check them, right when the valves get adjusted. Have to remove the intake manifold or the windshield wipers on the Fit to change the plugs.
 
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Use a voltmeter to test your wires. My opinion is that Accel makes the most durable wires. I have a vehicle with over 250K on a set of Accel wires and I have no complaints at all. As far as store brand wires, it's hit or miss to be honest. I have bought a brand new set of store brand wires and I had to take them back because it missed more with the new wires than it did with the old wires. OE wires are good, but sometimes I feel like they are inferior to premium brands such as Accel. However, an observation I've made is that the stock wires on imports last forever.
 

MC5W20

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Originally Posted By: dparm
The factory service manuals usually list the resistance the wires should read at. My Honda/Acura one certainly did. I generally replace the cap and wires every 50k. Plugs I do every 25k. Most mfg spec 50k or 100k for the wires.
In the GM factory manual, I saw a section on testing the wires. Its been a while since I sold the car, manual went with the car, so I don't recall the particulars. On both my Fords, I have the factory manual, and there is no descrpiption of testing the wires in either one.
 

MC5W20

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Originally Posted By: mechtech2
If yours have remained clean and dry, A good injector cleaner in the gas tank for one or two tanks can fix this.
They are clean, but have not been kept dry. The day before every oil change I spray the motor down with degreaser ( used to use purple power, now have switched to simple green ) then hit it with the garden hose. So they get wet quite frequently. I am going to either buy a set of cleaned injectors, or pull the ones in there and have them cleaned. Gotta wait another month for some decent weather here, though. I am a big believer on the ASNU fuel injector cleaning process. I've recently had to switch to 93 octane gas, vehicle runs much better on it, intermittent miss is a lot less now, and it is only at idle.
 

MC5W20

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Originally Posted By: FXjohn
i get new plug wires every 100-125k. I use OEM and have had bad luck with auto parts store plug wires. Where did you see the NGK wires? (to the original poster)
Well, I had a spark plug thread a few weeks back - and - I seen a couple of posts on NGK spark plugs and someone had mentioned there wires. So, I went to there web site and they had some really great info on spark plugs, while checking out the site I seen their info on plug wires, and it sounded good to me. I would have bought these if it weren't for the excellent deal I go on motorcraft wires. ( about $11 cheaper then what the NGK would have cost me ) Now, to the point. I could have purchased the NGK wires from Rock Auto, they are an internet retailer, and they have just about anything you would ever need for an automobile.
 
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I use the higher end magnecore wires as they are very high quality and there is nothing in them to wear out. They should effectively last forever.
 
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I bought NGK wires for the Suby when it got its 100K tune-up, I'm pretty confident they are quality wires. The Suby gets a tune-up every 40K miles. I also used NGK plugs, which are oem for that car.
 
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MC 5-20 - Spraying the engine down frequently can cause ignition problems. I avoid it. Wet wires can arc out, and once they start, they are leakers. Maybe you have to in your area with your particular particulates, but take it easy. Before you buy new injectors and go to the trouble of installing them, please try a good cleaner at full strength. It can fix them or at least clean things up in other areas. The combustion chambers will be cleaned, and you should be able to use less octane. Consider a new filter if you get new injectors.
 
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Belden wires from NAPA are very good stuff, and very reasonably priced ($38 for my Buick). I replaced the first set on my Buick only because one wire got partially slashed in an accident. They have a lifetime warranty.
 
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An odd thing I learned is that the current in a spiral wound ignition wire does NOT travel along the wire - not like a water pipe. It travels in a field that is produced outside the wire. Plasma?
 
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Originally Posted By: mechtech2
An odd thing I learned is that the current in a spiral wound ignition wire does NOT travel along the wire - not like a water pipe. It travels in a field that is produced outside the wire. Plasma?
That's an electrical phenomenon commonly called "skin effect" (more rarely "flashover"). It increases with frequency, whether it's done as a pulse in a spark plug wire or as very high freqency in, say, a microwave relay tower. In fact, in high-fq radio & MW applications, it's so pronounced that the towers are "wired" with hollow copper tubing- commonly called "plumbing"- simply because if they were solid, all that copper in the center would be wasted weight & expense. And by the way- the best explanation of spark plug wires I've seen is at the Magnecor website. No gee-whiz teenage-get-more-HP-from-XXmm-plugwire-diameter nonsense, just well presented information. You don't have to buy their wires to read, learn from, & appreciate it either. Here's a link; once there, click on "The Truth About Ignition Wire Conductors" to start. Link: http://www.magnecor.com/magnecor1/main.htm
 
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wires are cheap insurance against issues and if you replace them you can rule them out as source of any problems. I change em evey 50-60K and plugs every 25K, just too cheap not to do so and eliminate most potential problems. I run Mopar Perforemance or Magnecore wires. On my older cars cars with rotor cap, repalce those too with Mopar. Plugs I run stock Champion. Never have had any issues in 30 years of driving doing this routine. Of couse I know people who were too cheap to change plugs and wires and had the plugs frozen in the heads and paid big $ to have that corrected :)
 
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