Multiple Codes....related
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Postmaster
Joined: Aug 2004
Posts: 4,004
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From: North of Boston MA
Multiple Codes....related
So, my 2003 F150 4.6 that I just put back on the road after a four month break is running like crap. I took it off the road for the winter because it was missing (no codes) and didn't feel like dealing with it then but after running it for a day the CEL comes on. It shows the following:
P0304 - hoping it is a coil pack
P0456 - pending. Gas cap?
P0171 - pending. One bank too lean?
Does the 171 code possibly have to do with the misfire in Cylinder 4? I know it is impossible to tell yet but am hoping there is a potential connection.
Before I parked it in January, it was running a bit rough and stumbled on acceleration but never would show a code. Now all this. Going to change the coil first, tighten the gas cap, check for leaks and see what happens but is there anything common on these trucks that I should also be looking at?
Thanks in advance.
P0304 - hoping it is a coil pack
P0456 - pending. Gas cap?
P0171 - pending. One bank too lean?
Does the 171 code possibly have to do with the misfire in Cylinder 4? I know it is impossible to tell yet but am hoping there is a potential connection.
Before I parked it in January, it was running a bit rough and stumbled on acceleration but never would show a code. Now all this. Going to change the coil first, tighten the gas cap, check for leaks and see what happens but is there anything common on these trucks that I should also be looking at?
Thanks in advance.
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Postmaster
Joined: Aug 2004
Posts: 4,004
Likes: 1
From: North of Boston MA
Wish I had more than 10 minutes at a time...maybe I could actually work on the truck.
I will post back once I have had a chance to work on it some. Thank you for your posts SHO89- they are appreciated and trusted.
I will post back once I have had a chance to work on it some. Thank you for your posts SHO89- they are appreciated and trusted.
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Postmaster
Joined: Aug 2004
Posts: 4,004
Likes: 1
From: North of Boston MA
Okay, got some time to play with the truck today. It started and ran pretty smoothly and the CEL was out (I hadn't reset it). The code reader was still showing the P0304 Code and the other two as pending.
I put a vacuum gauge on it and was getting 20" at idle (brake booster hose) and absolutely no fluctuation. Seems good for 145k. I did check around the hoses and can't find any obvious vac leaks.
While I had the hose off I ran some Sea Foam through it. Didn't seem to change anything and threw no smoke at all.
I reset the codes and am going to drive it for a while and see if the CEL comes back on.
Doing this now.....
Any ideas?
TYVM.
I put a vacuum gauge on it and was getting 20" at idle (brake booster hose) and absolutely no fluctuation. Seems good for 145k. I did check around the hoses and can't find any obvious vac leaks.
While I had the hose off I ran some Sea Foam through it. Didn't seem to change anything and threw no smoke at all.
I reset the codes and am going to drive it for a while and see if the CEL comes back on.
Doing this now.....
Any ideas?
TYVM.
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
Just FYI, you cannot find an intake leak by looking at a vacuum gage test.
It would have to be so large you would have larger drivability issues.
The 171 code is detected by the OX sensor at a level so small you could not see this on a vacuum gage.
The code is set by proxy.
The Ox sensor tells the computer to richen up the fuel table after detecting excess oxygen in the exhaust (the lean condition in the description). This action makes the table go beyond a limit set by program.
This out of limit shift is what sets the code (by proxy).
Normally no connection to a misfire on one cylinder. The boot, coil or plug is probable cause. The code indicates the issue is on the secondary side of the coil circuit, not the primary side toward the PCM.
The Evap code is totally separate.
Good luck.
It would have to be so large you would have larger drivability issues.
The 171 code is detected by the OX sensor at a level so small you could not see this on a vacuum gage.
The code is set by proxy.
The Ox sensor tells the computer to richen up the fuel table after detecting excess oxygen in the exhaust (the lean condition in the description). This action makes the table go beyond a limit set by program.
This out of limit shift is what sets the code (by proxy).
Normally no connection to a misfire on one cylinder. The boot, coil or plug is probable cause. The code indicates the issue is on the secondary side of the coil circuit, not the primary side toward the PCM.
The Evap code is totally separate.
Good luck.
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Postmaster
Joined: Aug 2004
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From: North of Boston MA
Thanks for the reply, Bluegrass.
Been a while since I have been near the computer but here is what has been going on the last few weeks.
I changed the coil which immediately fixed the misfire. I reset the computer and been driving the truck more than usual and so far, no codes. I seems to be lower on power than it should but that may be because I am running the a/c more and have a cubic yard of wet mulch in the back.
Starting to think I need to scrap/part out the truck. The bed is going, the driver side doors are rusting out, it needs an exhaust and the tires are worn out. Hate to give it up but thinking the next repair that costs more than time may be the last...
Thanks again for the help.
Been a while since I have been near the computer but here is what has been going on the last few weeks.
I changed the coil which immediately fixed the misfire. I reset the computer and been driving the truck more than usual and so far, no codes. I seems to be lower on power than it should but that may be because I am running the a/c more and have a cubic yard of wet mulch in the back.
Starting to think I need to scrap/part out the truck. The bed is going, the driver side doors are rusting out, it needs an exhaust and the tires are worn out. Hate to give it up but thinking the next repair that costs more than time may be the last...
Thanks again for the help.
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