5.4L performance problems
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Senior User
Joined: Oct 2006
Posts: 186
Likes: 1
5.4L performance problems
I'm working on a 2002 F250 w/5.4 and 6-spd. 160000 miles. At 1st it was missing under load at lower rpm's (below 2200). It is also under powered. It should run stronger than it does. The miss goes away an higher rpm's but still no power.
This is what I have done so far:
-Check codes. none
-Check air filter and clean mass air flow sensor.
-Change fuel filter and check fuel pressure. 35 psi 42 psi with vac unhooked from pressure regulator. Not sure what the spec is.
-Fuel injector cleaning. This seemed to help the miss but not completely.
-Change spark plugs. They didn't look bad, but were due for a change.
-Compresssion check. All were between 160 and 180. Not sure what the spec is.
-Several of my coils had bad boots and some had bad corrosion on the terminal on the coil itself, and some look burned. I changed three so far ( the ones that looked the worst). Two of them look ok and three more are questionable. This made the miss go away almost completely, but it is still there a little bit. Still no power.
-Removed the exhaust at the flange behind the y-pipe to check for restricted exhaust. Still runs the same and with the exhaust off I can hear the miss more distinctively now.
I think I might take the exhaust off at the manifolds to eliminate a restriction. Should I keep going after coils? A'm I missing something. I'm running out of ideas. Please help.
This is what I have done so far:
-Check codes. none
-Check air filter and clean mass air flow sensor.
-Change fuel filter and check fuel pressure. 35 psi 42 psi with vac unhooked from pressure regulator. Not sure what the spec is.
-Fuel injector cleaning. This seemed to help the miss but not completely.
-Change spark plugs. They didn't look bad, but were due for a change.
-Compresssion check. All were between 160 and 180. Not sure what the spec is.
-Several of my coils had bad boots and some had bad corrosion on the terminal on the coil itself, and some look burned. I changed three so far ( the ones that looked the worst). Two of them look ok and three more are questionable. This made the miss go away almost completely, but it is still there a little bit. Still no power.
-Removed the exhaust at the flange behind the y-pipe to check for restricted exhaust. Still runs the same and with the exhaust off I can hear the miss more distinctively now.
I think I might take the exhaust off at the manifolds to eliminate a restriction. Should I keep going after coils? A'm I missing something. I'm running out of ideas. Please help.
Hotshot
Joined: Mar 2007
Posts: 10,101
Likes: 40
From: Pa
First thing I would do is replace all the old COP boots you didn't replace. Just because they look good doesn't mean they are good. I don't see the point in pulling off the manifolds. You could have a bad sensor and not even know it. Best thing IMO is to datalog the truck and make shure everything is functioning within specification.
Thread Starter
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Senior User
Joined: Oct 2006
Posts: 186
Likes: 1
The problem is that I don't have a book that tells me what the pids should be. I don't want to replace the coils if they are not bad. Usually if they are bad they will through a code, but they could just be worn out and not performing. Anyone ever here of this?
