One of mine just did and got it replaced, but it sure caused mis-fires and a compression leak. Unless I had a faulty spark plug, what else can cause them to crack? By the way, I baby my car and dont drive it hard. I have only 59K miles and I had the new spark plugs put in around 8 months ago, so they werent even that old before one of them cracked recently.

 

Usually running lean, heat, and incorrect gap. Most likely you had a defective plug. I had one in my last set, caused idle and low rpm acceleration issues.

 

What type of spark plugs?

 

OEM NGK

 

Did you check the gap and torque them correctly also? Sounds like I'm blaming you, I'm not. Probably defect like stphotographer said.

 

actually it could have been a gap problem like u say unless it was defected. This honda mechanic guy (not dealership) did them for me so it is possible he could have gapped them wrong. I think he said they came pre-gapped, but I was told afterwards that they arent pre-gapped. So I think he may have not gapped them right too maybe

 

OEM NGK's do come pre-gapped. I have only done mine once, so I'm by no means an expert or even an authority. I checked the gap anyway as I have read it is good practice. There was indeed very slight differences on the gap of 2 of them. One was a little "snug" (narrow) one was little "loose" (wide) I'm pretty sure they were all within spec. They are pretty difficult/stiff to gap. I just made my best effort to make the gaps uniform on all the plugs, within spec of course.
I guess they do come gapped, but you're supposed to check them anyway. So the mechanic guy is/was half right.

 

oh ok

 

What should the gap be?

 

Spark Plugs:
NGK: PFR7G-11S
DENSO: PK22PR-L11S

Electrode Gap:
Standard (New): 1.0-1.1mm (0.039-0.043 in.)
Service Limit: 1.3mm (0.015 in.)