Not sure what the problem is. I have 2000 Mustang GT manual trans. I recently changed the spark plugs and then my engine started a knocking in the engine, but only when it is in idle. Nothing seems to be wrong with the engine I checked the spark plugs again. i tightened one of the covers for the spark plug that the screw was stripped out and I fixed it so that it was tight then the knocking stopped. Then i went and cleaned the engine at a car wash with that degreaser stuff. Then once I pulled into my driveway and it was idleing down it started again very bad. Im not sure what to do to fix it. And it only does the knocking when the car is in idle only. If anyone has any ideas any would be appreciated.

 

Did you check to make sure the plugs were gapped properly?
Did you torque them down properly?
Are all the CoPs put back on in the right spot?
What type of replacment plugs did you use?

 

Not sure if it is a blown rod bearing or what?

 

I checked all the gaps, they were good. The plug i used as a replacement were the NGK R Vpower. The car is not knocking, that i just found out, it still has a weird noise to it and the engine bounces a little more than usual, but once the car warms up it all stops and runs great. So it still works(thank god)