My 03 hasn't been idling properly for a couple of months, cleaned the MAF and TB and it improved slightly but would still idle down to 400rpms and shake the truck and then bounce back up to 600-750. The NGK Iridiums in there only had 15K on them but decided to try and change them anyway. In researching if there was a better plug, came across information from NGK on determining if you were buying counterfeit plugs so pulled one of mine and sure enough, it was a fake (the printing on the porcelain was blurry and crooked - should have noticed when I installed them but 3 years ago, counterfeit plugs weren't on my mind.

Well, I got those plugs from Rock Auto so sent them an email with the photo of the one plug and my order number from 3 years ago. They immediately responded with an apology, said they were aware they had received some fake plugs but no way to tell who they went out to. Sent me six new ones at no charge and a 20% off discount code for my next purchase.

Installed new plugs (and all the rest removed were fake as well) and idle problem fixed and the truck actually feels "better". Hats off to RA for not insisting on all the plugs be photographed or returned to them, they just immediately stepped up and did the right thing.

So, if you have driveability problems, check your plugs - counterfeit Iridium plugs are not an urban legend and NGK gives you specific ways to check out the plugs.

Interesting. I need to check mine. I have the same symptoms. Lower idle and a slight shake then sometimes it’s smooth as butter. No codes. Did your MPG improve also?

@08TxRunner

You rang?

You were asking for links earlier, I'm just referencing someone who has had issues with fake plugs.

Appreciate it man. In the other thread, the post I was responding to inferred that the dealer is the only safe place to get spark plugs - don't trust parts houses such as Advance, Auto Zone, etc. That's what I disagree with.

I think everyone knows that buying parts off Rock Auto is risky. There are lots of posts on many forums about crap Chinese parts and counterfeit parts. It's kind of a given.

Never said it was the "only" place to get safe plugs, however it probably is the "safest" option. I bought on amazon and haven't had any issues, but for someone who is having issues with plugs not purchased from the dealer I feel like the best next step to take is buy plugs from the dealer. Rock auto vs parts houses isn't much different IMO except for price.

We'll just disagree on that point. I know that local parts houses buy from manufacturers. Online sales - Ebay, Amazon, Rock Auto, etc - always run the risk of counterfeits.

Why not just go to dealership for this?? This kind of stuff I am a huge huge PRO oem parts person for electrical and engine parts for maintenance and for good reason.. I know dealerships get bad rap but for parts I think not many beats oem!

Haven't had them in long enough to properly measure MPG but the dream-o-meter MPG gauge says yes, about 1mpg but I put very little faith in that device since it has never, ever been accurate when I measure mileage the old fashioned way.

Cost.

Any chance you can show a pic with counterfeit next to the real deal?

I just pulled these today. Orilleys bought, about 3yrs ago.

Here's a topic about fake Denso Iridium plugs with photos of both the real and fake plugs side by side, also observations of the differences, the fakes were bought off eBay, the real ones came from Rockauto.

PSA: Beware of Fake Iridium Spark Plugs (Ex. Denso SK20R11)

Thanks for posting this up. Had me pulling a plug this morning, even though nothing at the time at install gave me a reason to question them, just having myself 2nd guessing and being safe. Used the Denso this time.