Spark Plug Wires

devil_taz

How long do they last? Does it depend on the make and model of the vehicle?
Is it necessary to change them for every tune-up?
My car needs a tune-up really soon (165 000km) and I was wondering if it's a good idea to change them.

Thanks.

adc100

50K-75K miles. Except for AC-Delco which are good for 0-50K. I make it a practice to avoid them. They were no good in the 50's and 60's and are no good now (IMHO)

kinley

The engine was balking and running on less than 8 and being out of town, had them replaced in the big city for $325 total. Shop time = $76/hour and Sales Tax = 8.8% plus $9.50 charge to throw away the old wires. It's good to be back home again.

fleetwoodsimca

Do you despise thieves as much as I do? Given the opportunity, one must consider giving up a law practice, or medical practice in financial preference for a second career in professional automotive mechanics. >:o[
adc100 is right on in his estimate for service life on plug wire harnesses, IMO.

rayfbaird

I just replaced mine with Premium Bosh (copper wire) for 25.50. Changed them myself. Only a 4 banger though.

opera_house_wk

I don't ever remember replacing spark plug wires and I've driven several cars over 200K miles. I check them with an ohmmeter and if they are under 60K ohms I just put them in the dishwasher. None of my vehicles have ever had spark plug wells. If they did, I probably would replace them now and then. If you get the dirt and salt off they will last longer than the car.

brorjace

I let the stock wires go in my Honda Civic for 70,000 miles and when I replaced them using Accel ThunderSports, I got 2 additional mpg. >:^)

--- Bror Jace

q45man

My 90 Q45 has 8 coils, one mounted on each plug.
This topic will self extinguish as fewer and few cars are made with plug wires due to emission requirements.

rmyers76

I change my wires every time I change my plugs regardless of the condition. Every 50,000 miles I will do the spark plugs, wires, distributor cap and rotor.

I thought I could stretch the plug wires longer with the "lifetime warranty" wires but when I tried to remove them, 2 of the 6 wires pulled out of the boots. Now I just buy the standard grade replacement wires knowing that I will replace them in 3-4 years.

leadfoot4

I feel for you, and like most people, I think that you were "overcharged", to say the least. However, it might not be quite as bad as it seems.
I changed the wires on my 1996 Camaro this past winter. The wire set was $75 (Moroso Blue Max), and I, of course, did the labor. In order to access the wires, you have to drop the front end of the exhaust system, and the shop manual says to remove the power steering pump. I opted not to remove the pump, and all together the job took an agonizing 5 or 6 hours. Absolutely NOTHING is readily accessable on that car. Good thing I wasn't paying for the labor !!

devil_taz

cool thanks for the info guys.
I took my dads '96 Lesabre in for a tune up, an oil change, changing of the spark plug wires and replacement of the pcv valve.
The Total was around $400 cdn. SO DAMN $$$$. My friend told me that I got ripe off and it would be cheaper if I had gone to a independant shop (very hard to find a reliable one) But this is a one time thing since I don't need to replace them for another 150 000kms.

swschrad

I hope you enjoy those solid-gold wires, matching with the imported lead-crystal plugs.

seriously, in US$, I would expect a dealership computer-assisted diagnosis and tune-up on a recent car to suck up

$80-120 diagnostics
$30-40 spark plugs
$40-60 wires
$5-14 PCV valve

2 hours labor (call it $48/hour here)

and you'd still get a little ripped off on the parts, but not seriously. if you snap open a cold one and diagnose the car yourself with the tested ShadeTree Evaluator (yep, there's an engine under the hood, har har), using factory parts would cost something like

$10 spark plugs (from local chain parts house for the factory's own plugs)
$20-50 factory fitted plug wires (depends on source)
$4-7 factory PCV valve

1 box bandages about $2.50
1 tube Neosporin or similar antiseptic about $3.00

1 police fine for the neighbor calling about the cussed-blue air $50

and of course, if the ShadeTree Estimator didn't catch other parts and adjustments failed, extra costs at the dealer.

why the difference? your dealer does not get parts from multiple sources, and the factory parts department sticks them for a number of service replacement parts. the dealer's parts man has his "adder" for parts department profit, and the service department charges a flat rate programmed into the computer that often provides an "adder" for profit there. they may or may not charge the Mitchell's number of hours, depending on how badly warranty reimbursement hacks them, but they will make up the difference somehow.

the major cost difference is usually the computer diagnostic required for a successful tune-up nowadays. they might stick you double for the parts, depending on how evil the distribution chain is and whether that dealer wants after-sales service business, and the labor charges are usually required to be posted by regional laws.

the rest might be real and "pretend" exchange differences between $CDN and $US, which out of $400CDN, I would expect to be in the $100 range.

acelink

R7EQP NGK PLATINUM SPARK PLUG (LEADING) costs 10.50 apiece(?). Also, Ultra Cable (spark plug wire for 4 cyclinder) from Nagai Electronics Japan costs about $150 (heard about this brand?). Its manufacturer claim that it is 100% made of silicone or something. The vendor I talked to said, "just replacing the oem spark plug wire sets with this would net you some additional hps."

Is he telling the truth? Are they worth upgrading given their exceptionally high asking price?

brucer2

Unless a wire goes bad (missfire) there is no need to change wires. You can get leakage if the wires are dirty (high voltage & a pulse - AC, skin effect). Once a year I take each plug wire off, spray it with silicone spray and wipe the grunge off (get inside the boots also). This keeps them clean and flexible. The ires will last many years like this. A dishwasher doesn't sound like a great idea to me.
OEM wires are almost always good. NGK makes excellent replacements. Big buck, exotic wires are a waste of money with a stock engine.

opera_house_wk

A spark plug wire is just a conveyor of electricity. Almost all don't even have any wire in them. To reduce radio noise, they have been made resistive by making a bundle of carbon impregnated fibers or use of resistive plastic. The ones with wire in them have a thin wire wound on an insulating core core. They still radiate energy, but at a lower frequency that radios don't pick up. All you have to worry about is where the insulation touches other wires or the engine metal and the resistance, including the end connections. The dishwasher is a low stress method of cleaning the wires. Pulling on wires to clean them has the potential for more damage. I place the entire harness, including the distributor cap and spacers, in as a complete assembly. If you are including the distributor cap, do a second wash without soap to insure that no soap deposits are left on the surface. Pure deionized water is a extremely poor conductor of electricity. Water needs dirt and salts to conduct. WD-40 will clean but the surface will leave a coating to attract dirt. Then you are back to the original problem. Short periods of contact with water is not damaging.

wtd

Are plug wires supposed to arch when you touch them while the vehicle is running?

I have been having problems on my 5.7L chevy truck engine. I replaced all my ignition components last fall because of low power and arching of wires and coil. All was fine untill recently. I checked the wires again and I had one that was arching which was replaced.

I checked the wires again last night and although none were arching at idle, when you touched and moved the wires, they would arch. These wires only have 3,000 miles on them. Is this normal or are my wires shot?

Wayne

alcan

No, they shouldn't. Are they GM or aftermarket wires? Any oily engine residue on them?

wtd

These are AC-Delco replacement plug wires. They do not have any oil on them. I wiped them clean a couple of days prior to checking them and they only had dust on them then. I don't know whats up with this ignition stuff. I replaced my plugs, wires, coil, cap & rotor with all new AC-Delco replacements and thought my problems would be over for awhile. I'm thinking of getting some Magnacor plug wires as these are supposed to be very good. Any thoughts on why these wires would be doing this so soon?

Wayne

adc100

I have had far to many failures with the AC Delco Wire Sets. I have had much more success with Autolites.

opera_house_wk

The insulation on plug wires is about three times thicker than what would be used at this voltage in other applications. It should be remembered that the spark plugs gap limits the maximum voltage. If you measure with a DVM, you will likely find that the resistance (>100K)is quite high on these wires. To experience your problem, the spark plug end connection would have to be very poor. These poor connections create an internal arcing condition in the wire. The arcing vaporizes the resistive components inside the insulation. This increases the gap at this bad connection. The voltage dramatically increases and takes any path it can. So it could very well be poor manufacturing.

fleetwoodsimca

I have a friend who works for NAPA. He swears by their top-of-the-line plug wire harnesses. You might get results with them. How sure are you that you have set your spark plug gaps correctly? Are you POSITIVE that your plugs are recommended for this application? Have you checked out your coil thoroughly?

wtd

The parts store where I bought the ignition components will warrenty everything. I'm going to get a Borg Warner cap, rotor, and coil. As for the wires and spark plugs, I'm not sure yet. They carry Omnispark plug wires which I have used in the past with good luck. I'm thinking maybe NKG plugs.

fleetwoodsinca,
I'm positive I have the correct plugs with the gap set to factory specs. The coil was new but that doesn't guareentee that its not bad.

fleetwoodsimca

If you have a digital multimeter, you might want to run some resistance tests.
By the way, I used to sign on to Edmunds as wtd44. I noted along the way that you were a VERY close username, and to help keep ID's easy to ascertain, I switched to Fleetwoodsimca. My decision to do so was aided by a need to reformat my hard drive and reinstall my software! For good measure, I changed ISP's at the same time...

brorjace

Are NAPA ignition parts still being made by Accel? I heard this was true at one time ... but that was a long time ago.

I really like my Accel Thundersport wires for imports. Mine were fairly cheap at around $40 for a Honda 4-cylinder, they look nice (3 colors to choose from) and have only 150ohms resistance (if my memory is functioning correctly this morning).

I'll replace them again after 70,000 miles or so (maybe one more year). Still, they look brand new and it'll be hard to throw the 'old' ones away. <:^(

--- <b>Bror Jace

opera_house_wk

These must be that spiral wound wire on a core. That price seems about right for this kind of wire.

brucer2

Low resistance wires and plugs shouldn't be used on modern electronic ignition systems. You wind up with lots of EMI that not only creats staic on the radio, but can create problems with the engine computer. Remember that the ignition is a pluse and is therefore AC, so don't worry about 15-30k ohm DC resistance weakening the spark.
BTW, NGK also makes very good wire sets.

brorjace

I think those ARE spiral-wound wires ... but researched them and purchased them years ago now. I've forgotten and threw away the box.

Brucer, most sets will say if they are for the street or not. Taylor sells sets of wires that should not be used on the street. I'm pretty sure wiring with a resistance of 150ohms per foot is street-legal. I've had no problems with radio interference in the years I've used my Accel Thundersports.

Yes, you shouldn't use "race" wires on the street for the reasons you mentioned.

--- Bror Jace

int250

referring to post #24 Echlin (NAPA) manufactures Accel products ! Both brands are very high quality !

int250

MSW wires are the spiral wound wires and Pep Boys carries them.. I have used then in modern cars with no problem !

brorjace

Um, on a related subject, how long do spark plugs last?

My theory is that older engines, especially flathead engines like the ones made by Briggs & Stratton for lawn & garden equipment are spark-plug friendly. Even when these get fouled, a quick trip under a wire wheel and they are fine.

Some engines, especially newer, hotter-running motors actually wear away the electrodes but if the electrodes aren't worn and using a piece of fine-grit sandpaper you can easily get the electrodes down to bare metal.

Is that cleaned spark plug going to work as good as a brand new one? What else could be wrong with an old plug whose electrodes still look sharp necessitating its replacement?

--- Bror Jace

zr2rando

Just use a solvent and brush to get carbon and varnish off them. Main thing is the firing surfaces need to be flat and parallel,,,rounding off the corners is what kills them. Also check the insulator carefully for any cracks. If you are using inexpensive plugs it is usually cheap enough to replace them given all the effort it takes to get to them sometimes. Platinum usually does not wear enough to replace very often, usually just get carboned up and then you get some odd firing pattern if there is much gunk on them...if you have to adjust the gap be carefull, after all those heat cycles they may not want to move that one last time...years ago we used to clean them and file them repeatedly...lots of time, not much money, and pretty simple engines...
Those were the dayyyys!

adc100

I stopped cleaning plugs about 25 years ago, based on a technical article about plugs. If I go to the trouble of removing a plug I will not replace it with a used one. In a well maintained engine conventional plugs are good for about 30K. From what I have seen Platinum are good for maybe 50-75K. I really like the Bosch +4's. I pulled one at 25K and it looked almost new. Probably the only plug I will ever use.

brorjace

I clean and regap the plugs in My Honda Civic about halfway through their service life of about 20-25K miles. I do this to remove the light glazing that I find on the plug.

For our lawn & garden equipment, I find myself pulling plugs and cleaning them often. These machines sit for a year at a time, sometimes and when trying to start them after the've been still for half a season or more is tough. (especially the older ones) They tend to flood initially and they'll never start unless you pull the plug and clean the carbon and gasoline off it.

Anyway, we have an old Jari sickle-bar mower that is easily 30 years old and uses the ubiquitous CJ-8 in its B&S 4hp motor. I got it out of the barn where it was about 35F and it would not start as I predicted. I let it sit in the bright sunlight and warm up to about 70-80F for nearly 2 hours. I also changed the sparkplug ... but only had a slight newer one from a newer machine.

The machine fired right up. There was some discussion about what worked, the warmth or the newer plug. I think the warmth ... but I got new plugs for both machines anyway.

--- Bror Jace

I just think that if the plug isn't damaged or worn, it should not be much of an issue.

--- Bror Jace

opera_house_wk

There is a problem that might occur with cleaning plugs with a motorized wheel. An extremely fine metallic coating may cause the current to flow down the insulator. I restore a lot of antique engines and some I have to hit pretty hard with the wheel. They typically have long insulators and the section of the insulator with the metal coating isn't significant enough to cause shorting. The metal burns off quickly with use. I had a Mazda rotary that would suffer from lead shorting. This was back when there was leaded gas and it was cheaper. The car would skip on acceleration. The fix was one tank of unleaded to allow the coating to burn off. Then I could go back to leaded for a couple of months. Had a Toyota Supra that had a terrible time with BOSCH plugs that cracked insulators. To this day, I just can't buy a BOSCH plug. Never had any problems with NGK which would easily go 150K

mdey

Don't clean spark plugs with sandpaper. The grit from the sandpaper will deposit itself on the metal surfaces. Know how they make glass? With sand. That sand will glaze over the electrodes under estreme heat and interfere with the spark and cause the plug to fowl. It looks like carbon in short order.

The best way to clean a plug is to use a cleaning agent like carb cleaner. But then, as much work as it is to get the things out, I am reluctant to put the old ones back in. The platinum plugs are expensive, but so is my free time.

mdey

I heard Click and Clack say that best plug wires for a Ford are the Motorcraft brand from the dealer. Interesting assessment and one I have to agree with. I find they hold up longer than the Bosch sets I have purchased, and they run about $36 for a 6 cylinder car. Twice as much as the Bosch, but they last twice as long!

brorjace

All you guys still running V8s and V6s crack me up. It takes me about 20 minutes to change the plugs in my 4-cyl Honda ... and that assumes that I'm using plugs that need to be re-gapped. Those inline 4s practically serve their plugs up to you on a platter. My Camaro and so many of the V8s I worked on a decade or more ago were quite the project. My Dad's Mercury Grand Marquis are such a pain, he won't do the job without also replacing the plug wires. >;^)

Seriously, thanks for the info. I thought the ceramic insulator might get damaged over time and my lil bro' swears that he's gotten bad plugs right out of the box for things like chainsaws, etc ...

Now for the brand wars: I've used a number of different plugs in my Honda and NGKs work the best (most MPGs). I lost a touch of mileage with original Bosch Platinums and haven't been able to take the plunge and pay for their +4s ... but they do look neat. >;^)

I bought Split-Fire plugs once. Never again. I had them in my car for 3 weeks, noticed no improvement and sent them back for the promised refund (and I got it). After only 3 weeks, the plugs had already started to corrode significantly. I don't think I've ever seen a cheaper-made plug. <:^(

--- <b>Bror Jace

adc100

were a joke. Not really sure if the +4's are worth the money. I have put them in 5 vehicles so far and they appear to be worth it. I understand that Bosch spent a bazillion dollers developing the plug. Who knows??

fleetwoodsimca

Paying attention to my Pathfinder owner's manual, I pulled a plug at just over 30K, for a look see. The book said change them routinely at 30K(1998 model) but low and behold, the strange looking platinum plug I pulled was not the 1998 plug! A friend at NAPA called somebody "at Nissan" and they said 1998's that were manufactured late in the year got 1999 spec'd engines, but the owner's manual would not reflect that. The advise was to put the "super plug" back in the hole and wait for 60K to arrive, UNLESS some diagnostic other than mileage made it necessary to change now. I put it back in and voila! All is well.

brorjace

I like the idea of the Splitfire plug. Split the spark between two electrodes and open that ignition source to the center of the combustion chamber. This should make for more complete combustion but:

1) The plugs are made cheaply. The lack of resistance to corrosion was apparent after only days. I can just imagine leaving these in for a year or more ... especially during the salted-road season.

2) The spark probably jumps between the center electrode and only one of the prongs of the side electrode. Assuming this is what happens, it makes this plug no more effective than any other.

The Bosch +4 looks awfully neat but I hate to spend a lot of money on the unknown. Also, I wonder how do you measure the gap on a plug like that? Is it easy to adjust? CAN you adjust it? I'm also a little gunshy about spend more than $2-3 on some 'wonder plug'. <:^(

Like I said above, I've found nothing that gives me better MPG than the factory spec NGK V-Power plugs. And, at $1.99 each, I can change them every 25,000 miles with no trouble at all.

I was in an Advance Auto Parts today looking for NGKs for our Honda tractor, etc ... but they didn't have any. I was going to pick up some CJ-8s and RJ-17LMs for our other machines. The store had a display featuring all of these common plugs so I picked up and handful and headed for the checkout.

Little alarms were ringing in my ears and I couldn't figure out why ... at first. I looked at the packaging ... Hmmm, Allied Signal. Hey, aren't those the guys that make P.O.S. Fram filters? Yep. I put the plugs back on the rack and walked out the store. Maybe I'm just a miserable b@$tard but I wasn't gonna buy them. Nope, not on that day.

--- <b>Bror Jace

adc100

NGK plugs are as good as it gets. You don't/cant adjust the gap on the Bosch. As far as I can remember 10-12 years all plugs come pre-gapped.

I asked the guy at Advance Auto who had a direct pipeline with a test engineer at Bosh who of course indicated that the +4 was the 7 the wonder of the world (or is it the eighth). Anyway, I asked if the spark only jumped one gap at a time. He indicated that he saw a film where it jumped more than one gap at the same time. Can't swear to that though. Also I believe the +4's are used in Nascar circuit. I'll try to find out. If they are used here they must be good.

Later,
Al

fleetwoodsimca

We agree on this! I have had great luck with Autolite. Also of note:
In the past year or two, Champion Sparkplugs have had a renaissance and are (at least in some applications) quite impressive. The story I have heard is that they quit listing applications that were "close/close enough" and did a lot of direct vehicle testing and came up with many, many new specs and plugs. I replaced a set of 4 original equipment NGK's with Champions in a Kawasaki Vulcan at 4K miles, and was shocked by the improvement. Yes, this is anecdotal and proves nothing, except that the Kawa engine liked the Champions...

zr2rando

Spark just goes to the closest electrode, and when that one wears a little bit then another electrode becomes the closest one, and then when that one wears it moves to another....
Theoretically it keeps the gap constant because it has multiple electrodes to wear down instead of only one,,,these days most platinum plugs last a LONG time as it is.
Rando
I have not heard anyone say the splitfires worked well

opera_house_wk

I used an EDM machine to cut a 0.030 gap in the center of the outside electrode. This gave a sharp clean edge and he really liked the way they worked. A knee operation ended his racing and I never made any more. Wouldn't use them in a car cause it really weakened the electrode, he changed plugs every time he raced. Splitfires are just too crude of an electrode to ever work. My Mazda rotary came with dual electrode Champions that never worked well. After 2 months replaced them with NGK which had a curved dual electrode. The difference was night and day.

gsleve

for vw engines from 87 on to my knowledge the jettas came from the factory with bosch plugs these originals had 3 electrodes so this technology is not a new one especially for bosch they've had quite a bit of experience over the years with multiple electrodes in their spark plug design

It was greatly noticeable if you changed the original bosch mutiple electrode plug with their conventional plug the performance diminished the dealers and those who worked primarily on german cars would always insist that you use the oem multiple design bosch had rather than the conventional bosch plug