2001 Ford F150 V8 Four Wheel Drive Automatic 187000 miles
I recently had a misfire and check engine light, and the OBD-II reading gave a misfire on cyl # 7. I changed all the plugs and the misfire/CEL disappeared for about three weeks. Then it came back (the misfire and CEL) and the OBD reading again gave a mis on #7 but this time also said fuel pump secondary circuit high. I'm not sure if I may have caused the 2nd code from when I pulled the fuel rail (with the injectors conncted to it) to access the plugs, but my next step was to change the Coil on Plug over cyl #7. The CEL went away on its own, but the engine still missed. So I went ahead and changed the coil, and the misfire seems to have stopped (no more stumbling or hesitation). But then when I drove it, I noticed a new sound (nothing too horrible sounding) that only comes when I open the throttle. It sounds like a tick (almost like I can hear the injector shooting the fuel in or something else shooting air at a fast pace). After driving about 20 miles, the CEL came back. Could I have not fully seated the fuel injectors, thereby causing the sound? Does it sound like it could be anything else I'm not thinking of, like maybe a vacuum leak or something? As of now, the truck still hasn't repeated the misfire, but I'm almost sure the sound was not present before I changed the coil and removed/replaced the fuel rail.