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Benefit of changing the Spark Plug wires?

Another example of someone not doing routine maintenance. It makes me believe that all used cars are a terrific risk. Folks put things off (27 years for plug wires?, c’mon!) Do you thing that the oil/filter, brake fluid, tranny oil, filters, were done on time? C’mon. Scares me. I’m a real PIA about this stuff, my last daily driver got 585,000 miles without one engine issue. Anyone else have that experience? All I did was routine maintenance by the owners manual. Rocketman

Do owner’s manuals these days have a miles or time recommendation for spark plug wire replacement?

@GeorgeSanJose - manual says inspect at 60k miles or 4 years.

In 4yrs it would have only driven under 15k.

The rotors prob have about 50k - rotor happened to be after market part.

The parts are not cheap - NGK wires cost about $45 - car starts great actually. Still on original wires. So wondering?

@rocketman - what car is yours that did 585k?

My car spec ask to inspect every 60k - so the wires are running perfectly. Rotor were changed 10yrs ago ie 50k miles ago - happened to be aftermarket part.

I am very particular about preventive maintenance. Manual didn’t say change it.

I change Tranny (Honda fluid) /Brake fluid every 2 years. Also have a Excel spread sheet to mark it. Oil/filter are changed every 3k/12months.

NGK wires are $45 - so wondering about it.

“The parts are not cheap-NGK wires cost about $45 . . .”

Are you serious?

That’s a pretty good price for an NGK wire set, in my opinion

No offense intended to anybody


manual says inspect [spark plug wires] at 60k miles or 4 years.

@scioconf … I’m just an econo-box DIY’er, but that’s my experience too, either spark plug wires are not mentioned in the maintenance schedule, or there is a recommendation to inspect them at certain times/miles. I only have experience with a few cars though. The experts here see cars of all makes and models and years and various wire vendors so if in doubt better to follow their advice than mine probably.

It seems like the insulation material used in modern spark plug wires is considerably more robust than in the 60’s and 70’s. With cars of that earlier era spark plug wires were a common poor-running problem. You’d twist the wires and see cracks in the insulation, so you’d know it was time to replace. You’d have to replace the spark plug wires every 3 to 5 years usually b/c of this insulation cracking problem.

Contrast this to the insulation on my 90’s Corolla which has no visible cracking at all after 20+ years. It is common sense of course – even if the owner’s manual schedule doesn’t mention it – for a DIY’er to clean and inspect the spark plug wires at least as often as the spark plugs are changed. If there’s a question about whether the spark plug wire is causing a performance or drivability problem most shops have an o-scope they can use to visualize the spark current going to each plug. That test is quite effective at sussing out bad spark plug wires.

@GeorgeSanJose - that is a great tip about checking them out. I will do so tomorrow.

BTW, what is a close to OEM for the Distributor cap? Acura doesn’t make it anymore.
I know NGK is for wires. Acura has Rotor for under $8. I will see youtube about how to DIY

What is in some sense funny is in 1999 at 90k, when I took this car for oil change to some place like Jiffy lube (i was inexperienced and I do not go there any more) the guy asked me to change these wires. Now in 2014 with 158k, it is still going. Maybe like you said it was a bad product prior to 80s.

OEM vendor for a Dist Cap? Sorry, I don’t know. I recently switched doing business with a national chain of parts stores to a local independent parts store because the national chain just wasn’t able to help with that kind of question. The staff at the local store are happy to assist with questions like that. If one staff member doesn’t know, they won’t guess, they’ll ask someone who does. So I rely on them unless an expert here has already given me vendor guidance.

If you visit a web site like Rock Auto, when you page to the list of distributor caps for your make/model/year, usually some on the list will note “OEM” or “original equipment” or “exact replacement” etc. So that’s worth doing sometimes to give you an idea which vendor is best.

RockAuto didn’t find any - OEM part # 30102-PD2-016

I just looked-up dist caps on Rock Auto for my 90’s Corolla and – the same as you found apparently – there were none in the list specified as “OEM”. Airtex Wells had one noted as “O.E. replacement” but I don’t know if that’s the same as OEM or not. I’m thinking O.E. is probably not the same as OEM.

Here is a video on 1999 Integra - the guy ended up in changing the Cap only to get rid of the CEL. A reader comments that it just needed a cleaning (" The corrosion caused the issue you should have just brushed it off") - well I am learning and there is always a chance that I am wrong but in this case, cleaning seems to make sense to me - it is just a conductor and over time, it just got some dust. The point is also, nowadays even Honda has parts made in China - your old part might be better made and more durable.

Another video on checking spark plug wires:


The distributor is driven off of the camshaft

As the distributor rotor rotates, it transfers spark to the proper terminals on the cap. The spark then travels through the wires, on the way to the spark plugs

And the terminals do get crusty and worn, over time

So, to answer your question . . . Yes, you are wrong, because the cap is not “just a protection”

A car does not have to be bucking along to benefit from a new set of wires.

An aftermarket distributor cap from AutoZone or wherever will work just fine. The odds of getting an inferior cap are near zero. Unless the cap is cracked or carbon tracked why worry about it.

A set of NGK wires for 45 bucks is not bad at all. When I priced a set of Motorcraft wires out for my 8 cylinder Lincoln some years ago they were listed at 220 dollars.
That’s 110 per side so put into perspective, the 45 is very reasonable for a brand such as NGK.

@db4690 - Thanks for explaining it to me.
It makes sense as to why it should be changed. I have better ides as to what parts to buy now - will be ordering them soon.

This explanation also add value as to why the wires also needs changing.

BTW, my car has auto tranny. Acura auto tranny are Not trouble free - the one in there was replaced with a used part. After installing at 140k, m/c told me there is a sticky valve (?) that one of the gear shifts slowly (acts like a sports car) - and the one came out was not the original - meaning the car has its 3rd tranny in there now - bought it at 90k. Question is, if the auto tranny ever fails, is there a way I can fix it for under $800-$900? What are best ways to fix it properly?

Other than me, everyone at home wants Auto. My kids are learning to drive - this is a great car for it - so I have a need to keep it, even as a 3rd car. I also leave it at airport from time to time. Very roomy that I transported a queen bed - didn’t find another car with this reliability -maybe Mazda 323, Insight or prius still not that roomy & cost more. People are buying BMW mini. Don;t know why Acura doesn’t bring it back? Acura even changed names on their cars because people are referring their cars as Integra or Teg and not Acura - that they brought in RSX - nowadays they have letters for their cars, TSX, TLX, MDX and so on, because they wanted them to be called Acura. Whatever the name, we want cars. They killed Integra. Acura salesman said, people go there to buy mostly MDX. Others are not that hot.


“sticky valve” . . . could be a valve inside the valve body

If that’s the case, you might be better off getting the entire valve body

Pure speculation right there . . .

@sciconf … the cap probably needs more frequent replacement than the wires would. The material in the wires can degrade with time, but the cap wear out with each mile driven. Take a look at the rotor and the inside of the cap. As the rotor spins around inside the cap, the metal edge of the rotor sweeps past each of the metal contacts embedded in the cap. Each contact in the cap gets “hit” on the fly by the rotor tip each time that spark plug fires. Over time the metal on the cap contacts wears away and an air gap forms, which can affect the quality of the spark. The magic of how electricity behaves at high voltage is the reason this scheme even works at all.

Thanks indeed. Also for mentioning RockAuto & Wells part.

I just bought the Cap/Rotor assembly from them. I plan to do some test on the wires before buying the wires. I went to Pick n Pull this morning - saw several cars with sparkling blue NGK cables on them!

BTW, I note that you are in San Jose - I am nearby too.

My kid once told me that this car, likely fetch more in the market later on! I will have to wait and see.
Hondas never get classic value that I know of.

At Pick n Pull, they have a 1950 rusty, worn out, American car for $4k-5k!

Rocketman - Were you a traveling salesman ? I probably have not put that many miles on my personal car in 50 years. All of my commutes have been % miles or less except for a 2 year period and when you are an over the road driver sometimes you only drive to work once a week.