Do the Ignition Wires and Coil Packs ever need changing?

Ken4 · Dec 11, 2005

I noticed my '00 camry I4 with 91,000km is slightly faster when headlights are off, about 0.2secs faster in 0~100kph. Vehicle is mostly stock with no power robbing ICE system. So I decided to change my PK20TR11 sparkies with only 20,000km on them, and noticed there was no longer a problem with the car being slower with headlights on or off. But after only 500km of use, the new sparkies seem to have lost it's spunk again and is again 0.2 secs slower with headlights on. I tried changing to a new 55D23L battery but that didnt help either. So I decided to check my wires and coil packs.

Ignition Wire # 1 = 10.50 k ohm
Ignition Wire # 2 = 10.03 k ohm
Ignition Wire # 3 = 8.68 k ohm
Ignition Wire # 4 = 5.83 k ohm

Coil pack # 1 secondary resistance = 13.29 k ohm
Coil pack # 2 secondary resistance = 13.51 k ohm

According to Haynes Manual, they are all within spec. Ignition wires should be below 25 k ohm and coil packs secondary resistance should be between 9.7 ~ 16.7 k ohm when cold. So question is, if the resistances are all in spec, should I still change my wires and coil packs since they are about 6 years old? Will it make any difference you think? Thanks for your replies.

labman · Dec 11, 2005

At 6 years, I would go with new wires as prevenatative maintance. They are made out of rubber and eventually go bad. The resistance may still be OK, but they leak voltage. I would leave the coil packs go until they show signs of failure.

Kestas · Dec 11, 2005

Ignition wires with carbon core are considered consumable. The microarcing during use within the conductor eventually consumes the wire.

If the specs are still good and the insulator is made of silicone, I see no reason why you should change tham at this point.

Ken4 · Dec 12, 2005

One of my mates told me the problem im experiencing is due to poor grounding. And true enuf, after installing a grounding kit, my camry is no longer slower when headlights are on.

pmwalter · Dec 12, 2005

Didn't I see this same question on Toyotanation.com? You will probably get a better response from this web portal.

I replaced my wires on my 98' 5FSE with blue NGK's. Great looking wire of decent quality. Even if the old wires were still OK, $35 for prevenative maintenance is pretty cheap (IMHO).

Jim 5 · Dec 12, 2005

You'll notice a misfire when the coils fail.

Personally, I wouldn't change them out prophylactically (wanted to use that word for a while now).

moribundman · Dec 12, 2005

I always figured you couldn't have a "coil pack" and ignition wires. Isn't a "coil pack" a coil mounted directly on a spark plug? Then there's simply no spark plug wire.

Mud · Dec 12, 2005

Some cars have coil packs for every cylinder mounted on the valve cover with very short wires to the plugs. Our 02 Z-28 with the LS-1 engine had that setup.
Daughter's audi has the coil packs mounted directly on the plugs.

labman · Dec 13, 2005

The HO Quad 4 I had, used 2 coil packs in a plastic housing between the the cams. Each end of the secondaries connected to conductors imbedded in the plastic housing leading to terminals connected to to the spark plugs by short springs. The same coil fired both 1 and 3 every time when they came to the top of the stroke, one of them reverse polarity.

I suspect my Ecotec is the same way.

moribundman · Dec 13, 2005

quote:

Daughter's audi has the coil packs mounted directly on the plugs.

That is what I call a coil pack, a coil mounted directly on a spark plug like on a 1.8T.

For example, my 2.8 L Audi has three twin coils with six spark plug wires mounted forward of the intake manifold. Almost all Audi owners talk about "coil packs" simply because the coils are clustered in one location -- which is an incorrect interpretation of "coil pack."