I had just bought 8 new plugs for my car. They are NGK TR55IX. I installed the first 4 on the driver side...then started up the car...it instantly started misfiring. I then removed them to find out that 2 out of the 4 had cracked..one real badly. Im going to be returning these tomorrow. I think i might have had a bad batch of them....has anybody else had this problem before with NGKs? Iv installed and removed my old delco ones a few times and had no problems with cracking.

 

No prob here with my ngk tr55's bought them a year ago.

 

You probably over-tightened them, or cranked on them too hard in an akward angle. Just be careful replacing them next time, as they are ceramic, and break relatively easily.

 

I had bought some plugs for my dad and they were cracked, went to the store to replace then and the next 5 boxes the pulled out all had cracked plugs in them, Someone must have droped the box they were shiped in.