Repeated CEL with blinking Cruise light and Cyl #4 misfire report. Anybody help? on 2005 Subaru Forester

At irregular intervals, my CEL illuminates with a blinking Cruise light. My OBD II reader says it's a cylinder #4 misfire. I've changed plugs. Engine has 90K miles. Mechanic says engine has coil packs, but not "wires" to change. No symptoms, though. No oil or coolant lose. Run 93 octane fuel faithfully. No rough idle, and I feel nothing when the CEL illuminates. Car runs like a swiss clock, so we're baffled. Any ideas on what's causing this?

by in York, PA on October 21, 2011
Get Your Car Fixed at a RepairPal Certified Shop.
We certify shops based on expertise, quality work, and verified customer reviews
2 answers 1 comment
ANSWER by , October 22, 2011
coil, vacuum leak, injector or wiring issue. you need to let your mechanic diag it for you to pinpoint the failure. Roy
COMMENT by , October 22, 2011
Thanks for your prompt reply. With plug changed, absolutely no rough idling or breakup under acceleration, we've ruled out vacuum leak, O2 sensor, and MAS for now. Replacing the injector and coil pack, since wiring checks out. Mechanic's "gut" says injector, but while we're in there, we'll get the coil, too, and do a quick compression check on #4. I'll report back. UPDATE: On my mechanic's advice, we replaced both coil and injector on #4. After three-plus weeks, no indicators, so I'd say, "Problem solved." Thanks.
ANSWER by , December 06, 2012