Beware of Fake Spark Plugs

Discussion in 'Dodge Challenger General Maintenance' started by SRT-Tom, Mar 26, 2026.

Page 2 of 2
  1. Apr 19, 2026 at 10:52 AM #11
    fritzthecat

    fritzthecat Full Access Member

    Posts:
    440
    Likes Received:
    202
    Joined:
    Aug 15, 2019
    Location:
    Sunny Boca Raton
    Tom, from the looks of it, based on what our two cars came with, and on the RockAuto website, the Mopar ones ARE the NGK ones!

    HellKitten, have you changed the plugs in your car, and is it a 6.1? I’m guessing that buying from a Mopar dealer is the most expensive option.
     
  2. Apr 20, 2026 at 11:47 PM #12
    HellKitten

    HellKitten Full Access Member

    Posts:
    439
    Likes Received:
    177
    Joined:
    Sep 16, 2020
    Location:
    NH
    No sir.. not yet , mine is a V6 so probably a bit of a PIA. But I have purchased OEM plugs off eBay for my V6 jeep a few years back, don't remember what I paid but the cost must of been reasonable.
     
  3. Apr 21, 2026 at 6:37 AM #13
    SRT-Tom

    SRT-Tom Well-Known Member Staff Member Super Moderator Article Writer

    Posts:
    8,242
    Likes Received:
    2,795
    Joined:
    Oct 2, 2011
    Location:
    southern New Jersey
    I am using "garage queen" as a figure of speech. I don't have a garage- just a high quality Covercraft car cover.
     
  4. May 4, 2026 at 11:00 AM #14
    fritzthecat

    fritzthecat Full Access Member

    Posts:
    440
    Likes Received:
    202
    Joined:
    Aug 15, 2019
    Location:
    Sunny Boca Raton
    UPDATE…

    On my last post, I had swapped the plugs between #8 and #4, figuring that the CEL code would move to P0304, indicating a misfire on cylinder 4. I reset the code and drove around. Now it’s running fine, with only a very minor shudder in the engine at times, and no error code. So, nice, but why?

    Here’s a question - how does the computer detect a misfire? And since these engines have 2 plugs per cylinder, do they both have to be faulty or will the computer detect a problem if only one is bad?
     
  5. May 4, 2026 at 12:35 PM #15
    SRT-Tom

    SRT-Tom Well-Known Member Staff Member Super Moderator Article Writer

    Posts:
    8,242
    Likes Received:
    2,795
    Joined:
    Oct 2, 2011
    Location:
    southern New Jersey
    The PCM computer detects a misfire by monitoring the crankshaft sensor signal. If a cylinder does not fire, it will slow the crankshaft rotation at the time it should be accelerating. This slight fluctuation can be filtered out by the PCM and identified as a misfire. The PCM uses the crankshaft position sensor to determine the timing of the spark plug firing and the fuel delivery. If the PCM miscalculates any of these parameters, it can cause a persistent misfire.

    I would think that the PCM would detect if either spark plug is bad in a cylinder. That is because both plugs are necessary for a more complete and efficient burn (i.e., increased horsepower and torque), smoother acceleration, quicker throttle response and a more complete burn (i.e., fewer unburned hydrocarbons and other pollutants).
     
    Last edited: May 4, 2026
  6. May 28, 2026 at 4:49 PM #16
    fritzthecat

    fritzthecat Full Access Member

    Posts:
    440
    Likes Received:
    202
    Joined:
    Aug 15, 2019
    Location:
    Sunny Boca Raton
    UPDATE…

    Ok, so finally after swapping the plugs between #8 and #4, the CEL code did change to P0304, indicating a misfire on cylinder 4. So, that's enough evidence to say that it's the spark plugs failing.

    At this point I figure it's worth changing them all I'm just wondering what's the best tradoff between the cheapest plugs and the most expensive.
     
    baccaruda likes this.
  7. May 29, 2026 at 5:49 AM #17
    SRT-Tom

    SRT-Tom Well-Known Member Staff Member Super Moderator Article Writer

    Posts:
    8,242
    Likes Received:
    2,795
    Joined:
    Oct 2, 2011
    Location:
    southern New Jersey
    As previously stated, buy Iridium NGK plugs or the MOPAR ones. They will last you up to 100K miles. Paying a little more, up front, is your wisest choice. You don't want to be changing 16 plugs after 30k miles.
     
  8. Jun 1, 2026 at 6:39 PM #18
    fritzthecat

    fritzthecat Full Access Member

    Posts:
    440
    Likes Received:
    202
    Joined:
    Aug 15, 2019
    Location:
    Sunny Boca Raton
    Hey, Tom, appreciate the advice, but here's the confusion...

    Spark plugs come in 3 types, Platinum, Double-Platinum, and Iridium. The Mopar ones (SPLZTR5A13) are by far the most expensive at $10.88 each. They are made by NGK. But they're not Iridium, not even Double-Platinum, they're just regular Platinum. And it calls out another NGK plug (3381 G-Power) as a replacement and those are only $5.45 each. Wonder what the difference is?

    NGK has a Double-Platinum one (4998 Laser Platinum), supposedly better, for $9.23 each. Ok...

    NGK has a Iridium one as well (2314 Iridium IX), supposedly top-of-the-line, for $6.40 each! Quite a bit less.

    But they also have a closeout special on AUTOLITE XP5263 Iridium XP ones, for $3.06 each. That's a great deal compared to the Mopar ones. Is there really that much difference? The Autolite should be better, they're Iridium!

    So a full set of Mopars = $174. Full set of the NGK Iridiums = $102. Autolite Iridiums = $49.

    What's a muther to do??? :Big Laugh:
     
  9. Jun 1, 2026 at 6:56 PM #19
    SRT-Tom

    SRT-Tom Well-Known Member Staff Member Super Moderator Article Writer

    Posts:
    8,242
    Likes Received:
    2,795
    Joined:
    Oct 2, 2011
    Location:
    southern New Jersey
    I would buy the NGK iridiums. They are a great plug and are specified for the SRT. Autolites are mid-tier plugs and sometimes have longevity issues. After you install 16 new plugs in a HEMI, you don't want to do it again after 60K miles. Read the following link:

    Are Autolite Spark Plugs Good? An Honest Look at What You're Actually Getting - Daily Car Tips

    Here are the advantages of an iridium plug:
    • It’s as much as eight times stronger than platinum, so iridium can have a sharper center electrode that conducts a more durable, powerful spark.
    • Iridium is much harder than even platinum, so it resists wear for up to 25% more lifespan.
    • Iridium has a melting point over 4,400 F which ensures it can handle the hottest ignition systems.
     
Page 2 of 2