I am troubleshooting an overly rich rear rotor, and among other things tested I found my plug wires to be all 2.3K Ohms, even my spare used plug wires.

The FSM says 16K Ohms. Is the shop manual wrong, or are all of my wires bad. They are OEM NGK. My current set are less the 1000 miles old.

 

I think some aftermarket wires are lower resistance than stock. 16k ohms is probably the upper end for the wires to work properly.

I'd be more worried about infinite resistance, no resistance, or one wire that tested differently from the others. That's probably a better gauge.

Dale

 

Yes, but is the FSM right or wrong? I have oem plug wires, and they all test at 2.3k ohms.

 

I don't know why there would be a difference, but the fact that they all test out to the same resistance tells me there is not a problem with them.

 

the oem wires are NOT ngk, they are the black yazaki's. seems like 2.3 to 16k ohms is a huge difference though

but yeah, dales method is a good one, you're looking for one that doesnt match/open/short

 

The specs are 16 ohm per meter, the lead are less than 300mm in length. So about 5 ohms per lead would be the max ohms to be in spec.

 

since they're all the same resistance and are basically new odds are there is something wrong with your multi-meter, leads, testing method, OR they are 2.3k ohms because they're not actually oem, as j9fd3s said. (which i didn't know until now)

i know only basic electrical circuits, but 2.3k may be well within the acceptable range. as long as it doesn't damage the coils, lower resistance is only going to create more current.

 

someone actually looked in the FSM... as if it were better than guessing?

 

Here's some measurements I took when I changed my ignition wires. By the way, it's 16k ohms/meter, which is 16,000 ohms per meter.


Wires installed were Mazda P/N 0000-18-130A (plug wire set)

Measured resistances (in ohms)

Front trailing: (short blue)
new: 1.54k / old 3.88k

Rear trailing: (long blue)
new: 2.06k / old 5.03k


Front Leading: (short black)
new: 2.57k / old 6.60k

Rear Leading: (long black)
new: 2.27k / old 4.70k


Your numbers seem OK, but you might want to double-check. A couple other things you can do is check your ignition coils, and repeat the wire measurements after heating them (with a heatgun or hair dryer), to simulate the hot engine bay they'll be working in.



original thread, with more info:
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/testing-ignition-coils-spark-plug-wire-corroded-408014/

 

What's a few thousand ohms between friends? I apologize for the typo.

 

Thanks for all the replies. Scotty305, that was exactly what I was looking for.

I find it odd that the wires I got from MAZDA, with the foam rubber insulators, and L1,L2.. stickers and BIG BOLD NGK stamped on them are not OEM. If they are not OEM then what is?

I have checked everything to do with ignition and fuel delivery. Every sensor, wire, and hose, and the plug wires were the only thing out of line.

The plug wires are about 1 foot long, and at 2+K ohms they are a far cry from a divison of 16k/3.
I checked the 94 FSM online here thinking they updated the specs, but no dice.

Why couldn't they simply give the proper Ohms per wire like they do everything else. Must be a standard they use in every application.

 

My wires, purchased straight from Mazda Motorsports, looked the same, and I'm pretty sure they said NGK on them. It's possible that j9fd3s is referring to the original set of wires installed when the cars were manufactured, and Mazda has changed vendors since then. That would also explain the wide range of tolerances specified in the FSM.

As a matter of fact, I've got a photo of my old wires compared to the new ones, and they're slightly different:



-s-

 

mazda japan uses yazaki wires

mazdausa uses ngk

 

Yes, My car came with NGK when new!