My '03 2.5L X-Type came home running rough last week with the engine lite on.

I took it down to AutoZone where they read the codes for me. It P0304, P0455, P1314, and P1316.

Basically thses indicate a vacuum leak and a misfire in the #4 cylinder. I changed the plugs ~30,000 miles ago and installed E-3's.

I replaced the fuel filler cap tot ry and eliminate the vacuum leak and I pulled the coil and spark plug from the #4 cylinder. The plug was wet and smelled like gas so the cylinder was probably not firing. I did not run a compression test but I've changed the oil religiously every 5,000 miles and use full synthetic so the mechanicals should be fine at 120,000 miles.

I cleaned, dried, and replaced the plug and installed a new coil I got from a local parts store. Still missing. Any thoughts?

 

start looking for cracked air hoses...thats your vacuum leak