OK, now what?
Thread Starter
|
Senior User
Joined: Apr 2002
Posts: 201
Likes: 0
From: Schaumburg, IL
OK, now what?
'97, 5.4, 135,000 miles.
A few years ago my truck developed a bad engine miss. My mechanic replaced the plugs, and although it improved the situation, it still didn't run smoothly. I got a check engine code, so I took it back in. The code was P304, cyl 4 misfire. The mechanic replaced the COP and it ran smooth as silk. Recently I started having the same problem. The plugs had about 75,000 miles on them so they were again replaced. (After reading the posts here about changing the plugs I really wanted to do it myself, but I don't have a heated garage, and it's cold out here, so I had it done). The mechanic read the code before he replaced the plugs and it was P303, cyl 3 misfire. After replacing the plugs it was again better, but still not right. Check engine light came on again, this time it was P301. I checked with the mechanic, & he said that he had pulled all the COPs off before he replaced the plugs, so the COP from cyl 3 could have gone back on cyl 1. I replaced the COP on cyl 1 myself and figured my problem was solved. Wrong! I still have a mild to bad miss - it varies day to day. Some days it idles almost perfect, other days it pops every couple seconds. It misses most on acceleration - if I'm going up an incline I either have to just barely add pressure to the gas pedal, or really mash it. When the mechanic replaced the plugs he also removed and tested the injectors, and said they were fine. I threw in a can of injector cleaner, which didnt' help. So if the plugs are new, the COP is new, the injectors are ok - what do I check next? btw, since I replaced the COP (a couple thousand miles ago) the mil light has NOT gone back on, even though the engine keeps missing.
Thanks for your help, guys.
A few years ago my truck developed a bad engine miss. My mechanic replaced the plugs, and although it improved the situation, it still didn't run smoothly. I got a check engine code, so I took it back in. The code was P304, cyl 4 misfire. The mechanic replaced the COP and it ran smooth as silk. Recently I started having the same problem. The plugs had about 75,000 miles on them so they were again replaced. (After reading the posts here about changing the plugs I really wanted to do it myself, but I don't have a heated garage, and it's cold out here, so I had it done). The mechanic read the code before he replaced the plugs and it was P303, cyl 3 misfire. After replacing the plugs it was again better, but still not right. Check engine light came on again, this time it was P301. I checked with the mechanic, & he said that he had pulled all the COPs off before he replaced the plugs, so the COP from cyl 3 could have gone back on cyl 1. I replaced the COP on cyl 1 myself and figured my problem was solved. Wrong! I still have a mild to bad miss - it varies day to day. Some days it idles almost perfect, other days it pops every couple seconds. It misses most on acceleration - if I'm going up an incline I either have to just barely add pressure to the gas pedal, or really mash it. When the mechanic replaced the plugs he also removed and tested the injectors, and said they were fine. I threw in a can of injector cleaner, which didnt' help. So if the plugs are new, the COP is new, the injectors are ok - what do I check next? btw, since I replaced the COP (a couple thousand miles ago) the mil light has NOT gone back on, even though the engine keeps missing.
Thanks for your help, guys.
Senior User
Joined: Feb 2005
Posts: 142
Likes: 0
From: Clinton,mi
The problem with cop is they run in series so when one goes it does effect the life of the others.You can get the Motorcraft brand ones at murrays discount auto for $39.99 i ended up doing all 8 of mine after chasing it for about 3 months.My buddy had about 60,000 on his and had the same problem so he bought all 8 and all is well.One of the problems is the hood seal up by the windshield it lets water in on the motor and the cop dont like the water down in the sparkplug hole making it short out
Hotshot
Joined: Aug 2002
Posts: 12,679
Likes: 15
From: BC, Canada
Your dealer can watch the cylinder power balance on their WDS scan tool. Quite often that's the best way to find which cylinder or cylinders are misfiring. Without doing that and without any trouble codes you're just guessing.
