Counterfeit plugs in paradise? - DD kept hinting that it needed attention sooner than expected...
Recently the driveability of my 22 year old
DD started to draw attention to itself, and not in a good way?
Here's what I observed:
* Longer/harder starting. Sometimes would take 2 tries in order to light off?
* But ran well during during warm up? (Open Loop)
* Would begin hesitating once the O2 sensor warmed up and engine went Closed Loop?
My first thought was maybe the (unknown age) upstream O2 sensor was ready
for replacement? After all, there were 162K miles on the odometer, with the PO putting
on the first 120K? But then again, the O2 sensor wouldn't explain the hard starting symptom?
Hearing one of
@Schurkey's standard queries in my mind ("Are all the tune-up items in good condition?")
I decided to verify the common sense stuff first. You know, build on a solid troubleshooting foundation.
Pulling the plugs, I was completely surprised by the XL size of the gaps. I've never seen gaps this big in one of my own cars?
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So I measured the gap, and it was an astounding .088"? What happened? I *know* I verified/installed these at the factory spec of .044"?
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According to my records, I had installed these ~40K miles ago. I dug through my old photos,
and came up with this photo (dated 14 May 2020) showing these same plugs going in:
Spring2020: Same Denso IK20TT above, when new, on left, replacing PO's worn NGKs {unknown age/mileage}
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So why did the plug on the left go bad in less than 4 years and 40K miles while being driven by a pretty chill old man in not that big of a hurry?
NOTE: Back when Iridium plugs first superceded Platinum plugs, articles were written touting a 100,000 mile service life.
Here's the opening of an article written in a service magazine back in 2014 talking about the new Denso Iridium plugs:
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(credit:
Spark plug article)
****
So I was trying to remember where & why I originally decided to purchase these? Since I've
bought so much online, I first thought that maybe I ended up with some counterfeit plugs,
especially since I hadn't yet learned about how all the 'jewelry level' plugs are so prone to
being copied. But no, I bought these at a brick & mortar store. And then I remembered
that I was going to purchase my default NGK copper V-groove plugs, and these were
being offered on deep discount for almost the same money?
And then this evening while researching spark plug lifespan, I finally found the real answer right
from the horse's mouth on the DENSO global website:
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(credit: Current page from their website on this subject:
Denso plug life)
Wait a minute -- as a 'Murican I gotta translate those kilometers into things I can wrap my
head around. So, to ensure I avoid being 'inexpedient economically', spark plugs beginning
in I = ~
12,500 mile recommended lifespan. Long lifespan plugs = ~
62,000 miles.
Well I'll be dipped. As mentioned previously, I had installed a set of
IK20TT Iridium Twin Tip spark plugs.
And by doing so I had managed to purchase a set of 'regular mileage' Iridium spark plugs that Denso
conservatively recommends changing every 12,500 miles or so?
And that's how I learned that an K24a motor will become a bit fussy/balky when you put 40K miles on a
set of Iridium plugs that were specifically manufactured to a much lower price point? At the time I thought
I was getting Iridium for the price of Copper. But those old V-grooves will last a long time in an engine with
good piston rings & valve stem seals. Sure, they would wear with a lot of miles, but they never just disappeared
on me like that?
So the final answer is that I didn't get counterfeit plugs. But now I also know why these plugs were such a 'deal' at
the time of purchase.
****
Almost forgot. The fresh set of plugs cured ALL of the driveability issues I outlined at the beginning of this article.
With fresh plugs verified at a .044" gap, the K24a motor starts as new, and takes the clutch (5-spd) flawlessly, hot or cold,
Open or Closed loop.
As per usual, Schurkey was proven right to (virtually) ask what is the condition that the normal 'tune up' stuff is in?
Trust but Verify. And just because I *think* I know I've covered all the bases...well, sometimes I haven't read
all the fine print.
The moral of the story? Even when you manage to avoid counterfeit parts, you still typically get what you pay for... ;-)