Does spark plug wire really go bad

I replaced several loose wires on my 20 years old engine. The new wires ar e just loosely laying on top of the engine. I can already smell the burnin g rubbers. The old wires are nicely mounted with spacers, tabs and heat sh ields. It's hard to do the same without taking the engine out. I am tempt ed to put back the old wires by bending (or patching) the plug connectors, or perhaps an insert with new plug ends.

Does plug wire really go bad, other than loose connectors? Two out of six original wires are still working fine.

There are low EMI spark plug wires where the "wire" is actually a resistive filament. They sometimes degrade over time and heat.

But I don't think I've had to replace a spark plug wire anytime in the past 20 years.

You _can_ buy new "looms" (the "spacers"). ...Jim Thompson

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I think it's the vibrations shaking the connectors loose.

Front

4 1 5 2 6 3

But hard to get to the engine without taking it out. I can barely reach the "looms".

The insulation cracks in ways you can't see. Try running your engine at night in the dark. If you can see blue corona along the wires you are leaking power and when the get damp they will short out. That's been my experience on old cars. On newer cars the wires seem to be made a lot better and the insulation holds up for some year, but not forever. I've had to replace the wires and plugs twice in 220 kmiles. They are likely due for another replacement, but I don't have any problems yet. In the past I did have some misfiring which plugs and wires fixed.

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Rick C

You can often give a gentle squeeze (pliers) to the clip located inside the wire's boot so it grabs the tip of the plug a bit better. I've had wire sets that were "sloppy fits".

On my V8, the two rearmost plugs (and wires) are hard to access. (body shape, exhaust manifold, etc.)

But, I learned that if I lifted the front end and removed the front tires (one at a time, of course), I could just reach in through the wheel well and the plug was sitting there, bright as day!

On a dark night, start the car and open the hood- the light show will convince you! Maybe check with mfr. rep. for a premade harness?

you mean your 6 cyl engine is running on 2 cyls? Surely not.

Then wash & dry them thoroughly & try again. You may find they're fine.

NT

de the driver side next to the gas pedal. I drilled a hole next to the pas senger side for #3.

1,2,4,5 can be reached through the wheel well. 3 and 6 are further inside the center console, under the dash board. Many years ago, they charged $20 0 for changing plugs and wires on the Ford Aerostar. It's very touch to ch ange 3 and 6. Much easier with the hole for 3, but still difficult for 6.

Cheap spark-plug wires are filled with carbon-loaded silicone. The carbon burns from the ends, and when the gap gets big enough, you see the arc emerging in the surrounding space (why folk suggested looking at it in the dark). The arc is the symptom, but the cause is not cracking, but massively increased resistance.

If you get more than two years life from a set of these common leads, you're doing well.

If the leads are long enough, you can skimp by cutting 4cm from the burnt end (it'll be discolored) and re-fitting the ends. That's assuming you can undo the crimp and re-crimp.

However, if you choose wire-cored leads (often sold for racing), they are inductive rather than resistive. The core is a fine spiral of wire. This kind of lead is not too expensive or hard to source, and they last effectively forever. I've had Magnecore brand (I think) leads on my classic Alfa - the same set for twenty years, still working perfectly. Less radio interference than with cheap leads, as well.

Clifford Heath.

Two with old wires. Four with new wires. But the new wires are touching hot spots, with burning rubbers. The original wires are carefully mounted away from hot spots.

The wires are feet long. It is not creepage along the length of the wire insulator, it is conduction through a number of tiny cracks in the insulation. I don't think bathing is the answer no matter who does it, lol.

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Rick C

side the driver side next to the gas pedal. I drilled a hole next to the p assenger side for #3.

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e the center console, under the dash board. Many years ago, they charged $

200 for changing plugs and wires on the Ford Aerostar. It's very touch to change 3 and 6. Much easier with the hole for 3, but still difficult for 6 .

Loose connections mean very little unless the wire physically falls off. Th e wire is resistive and the current is so low it does not burn up. With the

fine, though it is hard on the coil(s).

If it has a distributor, which is possible on a Ford because they went to t he multi-coil system much later, you can take that apart and measure things and you will find that the tip of the rotor actually does not come into co ntact with the poles where the plug wires connect. Never had to. You just n eed enough firing voltage to get across.

What generally happens is the resistance of the wire goes up or the conduct or gets too many internal breaks. When that happens it can not only make th e plugs foul, it can cause the failure of the coil(s) or ignition module. T he fiting voltage is pretty much constant current, so if it does not arc, t he voltage goes up. If it goes on too long it gets to levels that can cause those other failures. If the insulation fails it can cause a fouled plug b ut usually will not hurt the coil(s) or ignition module. The current is pre tty much the same and the voltage is lower.

In most cases, you really do not need to change spark plugs for a very very long time, as long as those wires stay good.

I have had some damn good mechanics who apparently have three elbows on eac h arm and can turn their hands about 530 degrees stop to stop. I am almost serious here.

Anyway, if it is transverse front wheel drive, one way I have seen it done is they remove just one engine mount and push the car forward. I remember s ome cars that had that "dogbone" mount on the top and on some of them all y ou had to do is unbolt one side of that.

Another thing, if this is an older model and has aluminum heads, use a torq ue wrench to remove the plugs and if it requires more than about 120 ft lbs to break loose just stop. Wires are alot more important than plugs. And so me of them have a tendency to get stuck in the head (especially aluminum) a nd break off. Now you're in for a two (separate) day job and a trip to an a uto machine shop. You might try running it until it is warmed up and shooti ng LPS2 on it, but don't take that to the bank. (PB might work as well or b etter, not sure) It can work though because if it is an aluminum head it ha s about twice the thermal expansion coefficient of steel, which is what mor e spark plugs are. But then you got the problem that you might get a burn, and wearing gloves is not going to help much on these newer cars because sp ace is so tight.

Shit like this is one of the reasons I started paying people to fix my cars . In the old day I was pretty good and enjoyed it. Now, forget it. I'll hel p a friend truobleshoot one from time to time, but when it comes to turning a wrench, no more.

In the past, I've had the copper core spark eroded - the engine overheated and stopped, it wouldn't start again till it cooled down.

Most current HT leads have a carbon composite conductor - I've no experience with those.

yes

Misfiring probably cause other cylinders to work harder. The unburned gas is also bad for the catalytic converter, not to mansion the wallet for buying gas.

The engine ECU knows the misfire rate. I wish it would tell me the actual rate and cylinder map. Do they have that info in professional ODB tools? Mind only gives P0300 and the idiot CEL.

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s is also bad for the catalytic converter, not to mansion the wallet for bu ying gas.

l rate and cylinder map. Do they have that info in professional ODB tools? Mind only gives P0300 and the idiot CEL.

afaik p0300 means random or multiple cylinders, otherwise the last digit would be the cylinder number

and it doesn't have to be the ignition, it could be bad injectors

-Lasse

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gas is also bad for the catalytic converter, not to mansion the wallet for buying gas.

ual rate and cylinder map. Do they have that info in professional ODB tool s? Mind only gives P0300 and the idiot CEL.

The CEL & P0300 are gone, but the engine is still not as smooth as before. There are probably still some misfirings, but below the threshold.

I've tested them. About six ohms, compared to >50KOhms.

And internally, an encapsulated highly coiled wire that has nice high inductance. Little impedance to a spark, but lots to RF emissions.

I don't know what wires you're talking about, but mine are *not* like that.