Denso ignition cable resistance

[Alan in Alabama]

I ordered a set of Denso ignition cables for a 1999 3.4 V6 from Amazon. Denso 671-6182. Before installation I measured the cables' resistance. 1.6 kOhms, 1.6 kOhms, and 61 kOhms. One cable way out of spec. I returned them to Amazon. Then I ordered the same set from Rock Auto. They tested 1.6 kOhms, 1.6 kOhms, and 18 kOhms. Again, one cable way, way more than the other two.

Did both sets have one defective wire?

Are the wire sets designed to have one wire with much greater resistance?

Has anyone else measured their cables before installation?

By coincidence, or maybe not, the longest of the three cables in each set was the one with the much higher resistance, although the longest one in each set was longer by only a few inches than the others. I tested with two different VOM's. Same resistance values.

 

[Bad Luck]

I ordered a set of Denso ignition cables for a 1999 3.4 V6 from Amazon. Denso 671-6182. Before installation I measured the cables' resistance. 1.6 kOhms, 1.6 kOhms, and 61 kOhms. One cable way out of spec. I returned them to Amazon. Then I ordered the same set from Rock Auto. They tested 1.6 kOhms, 1.6 kOhms, and 18 kOhms. Again, one cable way, way more than the other two.

Did both sets have one defective wire?

Are the wire sets designed to have one wire with much greater resistance?

Has anyone else measured their cables before installation?

By coincidence, or maybe not, the longest of the three cables in each set was the one with the much higher resistance, although the longest one in each set was longer by only a few inches than the others. I tested with two different VOM's. Same resistance values.

Try installing them and see what happens. I've never measured the resistance of the spark plug wires, but I also don't go searching for problems before they exist.

 

[brillo_76]

My signature has a link to the thread on spark plug wire resistance measurements.

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[Bad Luck]

My signature has a link to the thread on spark plug wire resistance measurements.

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Your spark plug info link takes me to the main forum page. You need to add an "l" at the end of your signature link. That's a lower case "L" by the way.

 

[Alan in Alabama]

From this thread in another forum...

Spark plug wire resistance | Toyota 4Runner Forum [4Runners.com]

I deduced that the Denso cables have lower resistance than other brands. That's why I picked this brand of cable. And two of the three cables in each set do indeed have less than 2000 Ohms resistance. The third cable way more.

The cables in the car now are some AutoZone cables the previous owner installed and they are around 15000 Ohms and the engine runs fine.

Toyota specifies less than 25000 Ohms.

Still the mystery is why 2 of 3 are low resistance and one high resistance in each set I measured. On purpose? Quality control problem?

Brillo 76: I couldn't find the link you referred to. It goes to a menu of many items. Could you narrow it down?

For now I'll keep the AutoZone cables it's using. "If it works, don't fix it."

 

[Alan in Alabama]

My "conspiracy theory".

* The Denso cables limit radio interference by shielding a rather low resistance inner wire. Most cables limit radio interference by using high resistance graphite to carry a much smaller non radio interfering current.

* The Toyota computer may set a code if it sees too low a resistance in the ignition system. Denso realized this after manufacturing a bunch of cable sets. Rather than junking them all, they replaced one of the cables in each set with a high resistance conventional cable and it worked ok with only 2 of 3 high-tech cables. No one would ever check cable resistances if the car ran ok after installation.

Or maybe due to poor quality control 1/3 of the cables were bad. And by chance each set had 2 good cables and 1 high resistance cable.

 

[brillo_76]

Your spark plug info link takes me to the main forum page. You need to add an "l" at the end of your signature link. That's a lower case "L" by the way.

Fixed it..

 

[brillo_76]

From this thread in another forum...

Spark plug wire resistance | Toyota 4Runner Forum [4Runners.com]

I deduced that the Denso cables have lower resistance than other brands. That's why I picked this brand of cable. And two of the three cables in each set do indeed have less than 2000 Ohms resistance. The third cable way more.

The cables in the car now are some AutoZone cables the previous owner installed and they are around 15000 Ohms and the engine runs fine.

Toyota specifies less than 25000 Ohms.

Still the mystery is why 2 of 3 are low resistance and one high resistance in each set I measured. On purpose? Quality control problem?

Brillo 76: I couldn't find the link you referred to. It goes to a menu of many items. Could you narrow it down?

For now I'll keep the AutoZone cables it's using. "If it works, don't fix it."

We had a good discussion on that thread. The core of the spark plug wires that make the difference.

I fixed it.. Somehow my l was missing off the .html hence why it was messed up.

 

[brillo_76]

My "conspiracy theory".

* The Denso cables limit radio interference by shielding a rather low resistance inner wire. Most cables limit radio interference by using high resistance graphite to carry a much smaller non radio interfering current.

* The Toyota computer may set a code if it sees too low a resistance in the ignition system. Denso realized this after manufacturing a bunch of cable sets. Rather than junking them all, they replaced one of the cables in each set with a high resistance conventional cable and it worked ok with only 2 of 3 high-tech cables. No one would ever check cable resistances if the car ran ok after installation.

Or maybe due to poor quality control 1/3 of the cables were bad. And by chance each set had 2 good cables and 1 high resistance cable.

I like your theory. The mfg of the Toyota wires are made by Sumitomos at least back in the day they were. Might still be not 100% sure on if new oems are still Sumitomos.

 

[Alan in Alabama]

brillo 76... The new link works perfect. And the picture with where the cables go is very helpful.

Alan

 

[Malcolm99]

Use the Sumitomo OEM wires with date of manufacturing on it, they fit the plug wells and coils way better than aftermarket, when I changed my wires last year which said 1998 (24 years old) on them and still working perfectly fine, I installed the same Sumitomo OEM wires with the date 2022, truck ran exactly the same.

 

[19963.4lsr5]

I use the mag core wires sets. Been using them since the late 80’s

They are less than 1k ohm per foot. I am currently using car quest because their resistance was half the ones from AUtoZone.


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[brillo_76]

Use the Sumitomo OEM wires with date of manufacturing on it, they fit the plug wells and coils way better than aftermarket, when I changed my wires last year which said 1998 (24 years old) on them and still working perfectly fine, I installed the same Sumitomo OEM wires with the date 2022, truck ran exactly the same.

Sweet glad to hear the sumitomo wires are still an option.

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[TheDurk]

Sweet glad to hear the sumitomo wires are still an option.

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They were unavailable in the US for many years. The dealers only had Densos. That changed maybe ten years ago. I have to say I have ten years and 120K on my blue NGKs and the rig runs perfectly.

 

[brillo_76]

They were unavailable in the US for many years. The dealers only had Densos. That changed maybe ten years ago. I have to say I have ten years and 120K on my blue NGKs and the rig runs perfectly.

I am running blue NGKs as well. I just like folks to have a few options.

The magcore wires would be a good choice as well as they are lower resistance ones.

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[Malcolm99]

Yes the OEM Sumitomo wires are indeed available in Canada at Toyota, so I'm sure they are in the US. The NGK do not fit as well as the OEM IMO after installing each.