About 2 days ago i checked the spark plug for the cylinder closest to the passenger side (not sure if this is 1 or 4). The car was running fine but i was curious to see if these were the original spark plugs. They looked good so i put everything back together and drove the car a good 40 miles later that night. I took off from a stoplight and out of nowhere it starting misfiring like crazy, but without a check engine light. Me and my buddy took it back to his house and rechecked everything. It ran great the rest of the night. Well the next day it started misfiring just a little bit and the check engine light actually came on. So i checked the code and it said multiple cylinder misfire. I figured I'd try replacing the spark plug i had taken out the day before and to my surprise the ceramic had broken apart into small pieces. After about an hour of trying to get all the little pieces out to prevent them from falling into the motor, I put the new spark plug in. I start the car up and holy crap it's misfiring worse than ever. I shut it down, take the spark plug cover off, and start it back up. Now it's running perfect and continued to run great up until this afternoon. My check engine light popped back on again, but from what i can tell it isn't missing at all. The only problem i have noticed is that the cruise control will no longer shut off when i tap the clutch. I have to push it all the way in and the RPM's will rise about 2k higher before the cruise control disengages. Even the brake will not disengage it until i get on them pretty good. What would cause the ceramic to break and why is my cruise control acting up? I'm not an expert on all this computerized crap, but i know how to change spark plugs. Thanks for any help.

 

If you pull the plugs out you either have to replace the crush gasket or replace the plug. Did you replace all the plugs, or just that one? I would just replace them all and make sure you check the gaps. Also, I would make sure that you don't have a loose connection on the coil packs. The only other thing I can think is that you may have grounded something out and messed up the PCM.

 

replace the plugs back to stock and unplug the negative battery terminal to reset the ECU for 10 min . Then re-connect and test drive

 

Well it turns out that this time the CEL was for the thermostat. But the coil pack was a little loose and now its back to running like it should. Thanks