I have a 2004 Cavalier with a 2.2 Ecotec engine, I replaced the spark plugs over a year ago and had the wrong gap on them, too wide (0.05"), the car was working ok until recently had a check engine light and had to do with the cylinder 3 misfire. I decided to change all the spark plugs with the right gap but the light is still on. Is it possible that the coil got damaged due to the wrong spark plug gap?.

 

If it's running no. Is it running rough? Did you get the plug wires on correct?

 

The vehicle is running fine, power is ok, it passed the emissions test, and the only issue is the check engine light on the dash
I have not checked the electric wires.

 

That dtc is what needs to be posted. If you don't have a scanner is there an auto parts store that will scan it for you?

 

the coils (and modules) can go bad. I've even seen single cylinder misfires due to bad coils; even though it is a waste spark system.

it's coil over plug design so there are no secondary plug wires.

must be an intermitent misfire as this would never pass an emission test. Does it happen after the engine gets hot?

 

The DTC is P0303

 

How do I know if it happends after the engine gets hot? the MIL light is present all the time. I have change to premium fuel to see if helps but it doesn't

 

That is misfire #3 cylinder.What does #3 plug look like? Are these iridium or platnum plugs? Swap the plug with another cylinder, still the same, swap plug wire, no change, swap coil pack if the problem follows with any of the three that whats bad.

 

The spark plug looked orange/brown, these are iridium plugs. The vehicle does not have coil wires has an integrated module with 4 coils mounted on top of the spark plugs, so I can not swap coils, as far as I know. I put new spark plugs on all the cylinders and problem persist.

 

If it's not pristene white it is misfire. Common cause in fuel, mainly injector. Have you put any additive in the gas to clean injectors? If not, try that. The ignition system in my opinion (electronic) either works or dosen't. One other thing, with an insulated handle screwdriver put the end in the plug boot, and hold the shaft 1/4 or so away from the plug or ground. Start the car, the arc should be very bright white to blue, orange is no good. Make sure you aren't in any danger of fire, or in the exterior engine drive train.