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NGK Spark Plugs For Severe Cold?


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My daughter’s 95 Legacy (180,000 miles) had a misfire on cylinder 3 yesterday at about negative 25 Fahrenheit or colder. We plugged it in longer this morning (5 hours instead of 3) and it was worse this morning. We got misfiring on cylinders 3 and 4.

We evicted my wife’s 98 Forester (almost 299,000 miles) from its coveted spot in the heated garage and put the Legacy in to enjoy some tropical weather and get thawed out. It’s really amazing how much of a difference this makes for cars that spend most of the winter out in cold, to have a periodic thawing out.

Anyway, I took the spark plugs out (Installed 2019). They are NGK BKR6E. Only one looked a bit dirty—passenger side rear. The front one on that side looked a bit dirty too. We also replaced the wires in 2019 so I haven’t checked them for resistance.

So at one stage my other daughter brought home new spark plugs for her 96 Legacy: NGK BKR6E-11. I think they are viridian. Anyway the engine rain smooth on those plugs but kept causing a misfire code, maybe cylinder 3. So we put in the standard NGK plugs: BKR6E. No more misfire code. 

So I am wondering if the BKR6E-11 with the viridian electrode might work better in cold weather?  Or another NGK plug? Any thoughts on this? I decided to put them in as an experiment. The weather is forecast to be warmer tomorrow: warm up to -15 by tomorrow morning and get up to a tropical negative 7 by the afternoon. Then colder again Thursday-Saturday.

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2 minutes ago, Ravenwoods said:

We also replaced the wires in 2019 so I haven’t checked them for resistance.

what kind of wires? it does make a difference. wires should be OEM or NGK replacements only. NO parts store wires!

and i would run the plugs that are specified for the engine. double check the gap is correct.

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The difference between BKR6E and BKR6E-11 is the -11 is a V tip. Both are copper core with nickel tips. Both are gapped at .44.

Maybe the plug that misfired has a crack in the porcelain.

If you want to try a hotter plug, it would be BKR5E or BKR5E-11. The lower number is hotter, the reverse of other brands.

You can get a misfire code if the spark is leaking out around the coil and not reaching the plug.

Our 95 just did it on number 2. I used a wire grounded on one end and moved the other end around the coil. When I got close to the rubber cap on 2 it sparked. I cleaned all of them and added some dielectric grease, problem solved.

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9 hours ago, Rampage said:

The difference between BKR6E and BKR6E-11 is the -11 is a V tip. Both are copper core with nickel tips. Both are gapped at .44.

Maybe the plug that misfired has a crack in the porcelain.

If you want to try a hotter plug, it would be BKR5E or BKR5E-11. The lower number is hotter, the reverse of other brands.

You can get a misfire code if the spark is leaking out around the coil and not reaching the plug.

Our 95 just did it on number 2. I used a wire grounded on one end and moved the other end around the coil. When I got close to the rubber cap on 2 it sparked. I cleaned all of them and added some dielectric grease, problem solved.

Thanks for the great information.

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19 hours ago, heartless said:

what kind of wires? it does make a difference. wires should be OEM or NGK replacements only. NO parts store wires!

and i would run the plugs that are specified for the engine. double check the gap is correct.

I’m not sure what brand, but not NGK. I have a spare set of new NGK wires on hand in case any of our Subarus need a new set. We have four Legacies and one Forester—the youngest is the 98 Forester with almost 299,000 miles.

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8 minutes ago, Ravenwoods said:

I’m not sure what brand, but not NGK. I have a spare set of new NGK wires on hand in case any of our Subarus need a new set. We have four Legacies and one Forester—the youngest is the 98 Forester with almost 299,000 miles.

I would start by putting those NGK wires you have on hand into service.

Store brand wires are known to cause misfires, and all sorts of other "weird" issues.

I have learned this lesson the hard way, no way will I EVER use store brand wires on a Subaru ever again. OEM or NGK only for my Subies.

 

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4 hours ago, heartless said:

I would start by putting those NGK wires you have on hand into service.

Store brand wires are known to cause misfires, and all sorts of other "weird" issues.

I have learned this lesson the hard way, no way will I EVER use store brand wires on a Subaru ever again. OEM or NGK only for my Subies.

 

Thanks! Will do. My daughter reported that her car behaved perfectly today—like a new car.

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