2002 Pontiac Firebird Cylinder 3 misfire

[quote:587ef02f8d="Cgill"]Engine Mechanical problem
2002 Pontiac Firebird 6 cyl Two Wheel Drive Manual 118000 miles

Good evening all,

I am a relative newbie to car repair and am having
some difficulty with my 2002 Pontiac Firebird. After
taking it to Advance Auto Parts and running a brief
free diagnostic on it. The code P0303 came up
indicating a cylinder misfire. I have since changed
replaced the spark plugs and wires and am still having the same issue. The second diagnostic at Advance
Auto Parts revealed a cylinder 3 misfire. Does anyone
have an idea what could be causing this misfire? Any help would be greatly appreciated.

Thanks[/quote:587ef02f8d]

Hello,

Thank You for the Donation

common causes include bad spark plug wires, worn or fouled spark plugs, a weak ignition coil, dirty fuel injectors, low fuel pressure, or weak valve springs.

Other causes...

vacuum leak in the intake manifold, throttle body or vacuum plumbing, a defective Exhaust Gas Recirculation (EGR) valve that is leaking exhaust into the intake manifold.


.

You need to check to see if there is power to the fuel injector. If there is, and everything else is new, check compression in that cylender.

Let me know what you find.

Joe