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Incredible Power Gains, but harsh cold start - BKR8EIX

3174 Views 7 Replies 6 Participants Last post by  obermd
Hey guys, this is a topic about the NGK Iridium IX BKR8EIX spark plugs I replaced in my 2014 chevy cruze with 40k miles on it.

I replaced the plugs a little early because I read on here that they were not gapped right from factory, but that was wrong.
Stock plugs came factory gapped 0.028 which is what this vehicle was optimized for.

Out of the box, the
BKR8EIX plugs came gapped at 0.030, so I put all down to 0.0.28 for blowout

Here are my results:

The stock plugs started very good in harsh winter temps, and have had 0 problems with accelerating however real speeds could only be achieved by WOT, they turbo didnt really charge up the engine too much as I pressed the gas. My car had idle surges that were fixed with the
BKR8EIX as well. Plugs came out after 40k miles looking beautiful dark gold-redish color, my engine is running perfectly combustion wise.

These iridium plugs start very poor in colder weather temps, the engine really slugs and slowly turns over, is this bad? should i replace plugs? but they start fine in hot temps

Performance wise:
The BKR8EIX plugs offer incredible power gains, unlike stock plugs, when i am in 6th gear on the highway about 60mph and 2k rpm, I can literally feed the engine power as I just slowly hit the gas, i now much easily pass cars and my car overall is MUCH faster, huge noticeable differences I can swear by. only works run I am running shell v-power 93 btw.

mpg averages are very slightly lowering with iridium

So what do you guys think? Back to the stock plugs or can I keep the iridiums without the harsh cold starts?
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It sounds like something is wrong to me. Idle surges could definitely mean the plugs are misfiring or not firing at all at cold temps. Before you replace, try the gap at 0.030 and see what happens. I mean if you're gonna replace them anyways its worth a shot.
Mine didn't run well on cold starts with the 8EIX (weird hiccup in power), so I dropped back to a 7 heat range, but not the stock plugs. Otherwise, they ran very well.
I'm actually dropping back to the vPower BKR7E copper plugs. The 8EIX are the best of the iridium plugs but not as good as the copper plugs.
I'm actually dropping back to the vPower BKR7E copper plugs. The 8EIX are the best of the iridium plugs but not as good as the copper plugs.
Yep, that's exactly what I did.
I'm tuned so the coppers needed to be touched every 6000 miles. I couldn't tell between 7EIX and 8EIX plugs.
Apparently I'm the odd man out here...Still on stock plugs, approaching 100k, and can't say I've seen any reason to change them.
My experience is that the coppers should last about 15K miles for me. The 7EIX only lasted 20K and were significantly more expensive and not nearly as responsive as the 7EX. I have a set of 7EX sitting in the box so when I pull my 8EIX this weekend I have a backup set if I need to replace them. I'm getting spark blowout at WOT starting around 3K RPM.
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