Spark plug gap discrepancy between manual and pre-gap.

My new spark plugs, Denso Iridium SK20HR11, are pre-gapped at 0.037". My manual calls for a 0.043" gap. Should I re-gap the spark plugs or leave them since they are iridium?

 

Where’d you buy them from?

 

This is from AllData

 

Bought from an auto parts dealer on eBay. They're definitely genuine parts and from a US dealer.

 

I don’t believe that one bit, as someone who is a mechanic I wouldn’t trust those but you do you

seen it happen way too many times

 

Perfect world you want the largest gap possible without the spark blowing out to expose as much flame front as possible for maximum combustion.

Real world, .002” aint going to make a hill of beans difference. I’d run em.

 

First. This ^^^.

Second. OP: adjust the gap closer to 1.1mm.

I have bought 3 sets of these Denso Iridiums. Two from a Toyota dealer and one from an authorized Denso reseller, Advance Auto Parts. Not one plug out of those twenty-four needed to be regapped. Everyone was spot on.

If it was me, and I was getting this feedback, I wouldn't dick around and would spend the $70-$80 and source them from an absolutely 100% reliable source. Such as the two I mention.

Also, search around this forum. There's a thread somewhere from about 3/4 years ago where the physical differences in the plug box and the plug itself are shown (photos) for the counterfeits.

 

I just did my spark plugs, I bought OEM straight from Toyota cause I wanted the quality, I could’ve bought Denso through Oreillys or advanced or where ever, but I wasn’t happy with the way the Denso non oem looked. I did get I think 2 spark plugs from Toyota where the gap looked a little funky and I just had them swap them out

 

I am one of those people who received counterfeit plugs and didn’t know it until I pulled them and inspected more closely. Long story short, I purchased them from Amazon - not a reseller on Amazon, but Amazon itself, hoping that it would lend legitimacy to the parts. Price was a few dollars cheaper per plug than the dealer, so no alarms went off. My dealer wants ripoff prices compared even to local parts stores. I installed them at 120k-ish and noticed no change in idle or mileage. In other words, they were no better than the worn factory plugs with 120k miles on them. I attributed it to the miles and weight of the vehicle.

Shortly thereafter, I starting getting what felt like a slight miss at idle, but it didn't trip a CEL and it was very intermittent. So I attributed it to poor quality fuel and started using a different gas station and occasionally higher octane fuel (I was still using Regular unleaded at the time, which I don't recommend to anyone, but that's another discussion). The miss was still intermittently there and my mileage slowly decline a little bit - which I again attributed to more aggressive tires and more weight in the truck.

After 60k miles, I wised up and purchased another set of new plugs from a dealer when they were on sale. I decided to swap them just because I was doing a slew of other maintenance. Mileage jumped 2-3 MPG, idle was smooth and silk, and the truck ran better than it had in years. So I inspected the plugs.

Plug gaps were all over the place. Comparing printing on the plug bodies, colors were a bit off, inking wasn't consistent, layout varied a scoche - all the tell tale signs of counterfeits. Then I found this plug:



Hint - look VERY closely at the electrode.. So I swore off Amazon and eBay car parts, even if from what appears to be a reputable source. Same goes for tools like Milwaukee: I got several very good knockoff m18 batteries that looks 99.9% legit. They almost fooled me but I could tell the difference and noted as much. I'm guessing the average homeowner would have no idea.

 

And here's what the plugs should look like when they come out of the 3UR. Or close thereto.

 

Gap to your preference & install...

 

Buy the real deal, my friend

 

That’s the proper Toyota part number for plugs then. Curious as a friend thought 5.7 and 4.7 use same plug. Is this true?

 

I know both are iridium’s, but I honestly can’t remember the p/n, very well could be the same

 

I’ve checked. Definitely different.