Hey, i just bought a 05 RSX-type s w/ 62K on it. the CEL for cylinder 4 misfire came on the other day, and turns on and off every once in a while... I just changed the spark plugs, and there was slight "rust" residue on some of the coil packs... The CEL hasn't came on since i did the plugs.

How can i diagnose the problem further?

 

if it specifically cyl #4 swap your coil with another cyl and see if the problem changes cylinders also

 

I HAVE THIS SAME ISSUE.... ONLY ON NUMBER 4, AND IVE SWAPPED COILS AND IT CAME BACK ON AFTER 826 MILES AFTER THE FACT

 

check valve lash , clean your grounds.

 

I have a friend who has this issue before and his was due to 1 of the injectors not firing properly. Not sure how true this is being that he told me word of mouth and I didn't actually get to see if for myself...