I’ve just replaced the stock NKG plugs IZFR6K13 with IZFR6K11 on my 06 EX 2.4L with 50K miles and immediately I notice that I now need to turn the key all the way to the bottom and stay a bit there before car can start. I did not have this issue with the old plugs. However; with the new plugs, I am getting better idle, acceleration, and quieter drive.

During plug installation, I tightened the plugs around 3/8 turn (between 1/4 and 1/2) passing finger tight as most the plug instruction available from the web suggest 1/4 to 1/2 turn. The NKG instruction on the plug box however suggests 1/2 to 2/3 turn. Could my ignition problem due to not tightening the plug enough?

I did not replace or adjust anything else other than replacing the plugs.

Thank advance for your input

 

Did you gap the plugs which is the difference between the IZFR6K13 and IZFR6K11. I tighten spark plugs by feel and believe you did just fine in tightening but the difference in gap may be enough to change the characteristics of your vehicle a little.

 

I did not re-gap the plugs and use pre-gap .044” came with IZFR6K11. I figure IZFR6K13 has a bigger pre-gap (.052”) which will require a bit more voltage to ignite therefore hard to start but I am getting the opposite. I am confused if the tightening seems fine.

 

I would gap the plugs to specs for your Honda and see what happens. A bit more voltage may give you a hotter spark. You can torque the sparks plugs to put your mind at ease.

 

I use a torque wrench on sparkplugs, just because I own a torque wrench sitting right there in my toolbox.

If your coil is OK it should be able to make a good spark across either 1.1mm or 1.3mm gap. That being the case, the difference is the size of the spark (15% smaller) and the corresponding amount of energy in that spark.

Once the engine is running & it gets just a bit warmed up, the fuel is easier to ignite. That probably explains what's going on.

 

Thanks guys for the reply. Re-tightening did not seem to help. The car drive better so I will just have to assume the ignition difference is due to smaller gap size of the plugs.

 

The owner's manual states to tighten the plug 2/3 of a turn, after the gasket contacts the head. 3/8 of a turn would be pretty light compared to that. Did you tighten them? 13 lb-ft?

What's the verdict? Which plugs are better, overall? What Jim Blake says sounds logical to me, with regards to the ignition.

 

If I understand NGK's numbers, IZFR6K-13 & IZFR6K-11 are identical plugs, gapped to different gaps. But the -11 plugs (0.043" gap) are correct, according to NGK's website.

So if you can adjust the gap without breaking the tiny bit of iridium off the electrode, you can turn one plug into the other. But... it's easy to break that thing off.