my engine turns over but it won't start. i took out one spark plug(the front right if your looking at it from the front of the car) to see if i had a spark, i turned the engine over and it didn't create a spark but the engine started. but when i put the plug back in the engine wouldn't start anymore. could some one please explain whats goin on?
thanks

 

Moved: This should help you better.

 

Let me see if i understand this correctly:

Your engine turns over but doesn't catch. You have narrowed it down to no spark. You pull the #1 plug (thats the plug on the driver side, closest to the front) to visually verify the no-spark condition. You turn the engine over and you get no spark through the #1, but the rest obviously spark as the engine catches. Upon placing the plug back into the hole, it continues its no-start condition.

That's how i am reading it. How are you testing the spark? Have you checked the other 7 plugs?

Just a WAG, but whens the last time the ignition module was tested/replaced? That has a tendency to just go "bad" without any warning. They can commonly act like that "no start, then it starts for a bit, then it doesnt start."