Lean Banks
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7th Gear
Joined: Feb 2022
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Lean Banks
I've looked through the forums but couldn't find what I needed for certain.....
I've got a 03 Expedition with the 4.6. It was damaged, body damage only, and parked for about 20 months. While I had the front fenders, grill, bumper, etc. off I replaced the oil pump, timing chains, timing gears, guides, the works. Got it all back together and replaced the plugs and coils. It still appears to be "missing" while idling and moving. It almost immediately stored 4 codes that all indicated lean banks, poor air/fuel mixture and failing O2 sensors. There are no codes to indicate an actual misfire on any cylinder.
So, I'm replacing all the O2 sensors.
Could the EGR be stuck, or failing, after sitting? Should I replace it as well?
Any other suggestions are greatly appreciated!!
I've got a 03 Expedition with the 4.6. It was damaged, body damage only, and parked for about 20 months. While I had the front fenders, grill, bumper, etc. off I replaced the oil pump, timing chains, timing gears, guides, the works. Got it all back together and replaced the plugs and coils. It still appears to be "missing" while idling and moving. It almost immediately stored 4 codes that all indicated lean banks, poor air/fuel mixture and failing O2 sensors. There are no codes to indicate an actual misfire on any cylinder.
So, I'm replacing all the O2 sensors.
Could the EGR be stuck, or failing, after sitting? Should I replace it as well?
Any other suggestions are greatly appreciated!!
Laughing Gas
Joined: Feb 2003
Posts: 877
Likes: 27
From: South Florida
Any rodent damage to the harness while it was "stored" ? Most likely culprit is a vacuum leak. Best way to find that is with a smoke tester. Otherwise you will replace a lot of parts and waste time unnecessarily.
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7th Gear
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Now that you mention it....
Any rodent damage to the harness while it was "stored" ? Most likely culprit is a vacuum leak. Best way to find that is with a smoke tester. Otherwise you will replace a lot of parts and waste time unnecessarily.
Mechanics Smoke Test Machine on Amazon
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Mechanics Smoke Test Machine on Amazon
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7th Gear
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Codes
Not sure what freeze frame data means. Forgive me....I'm no mechanic. I like to try to do my repairs as a learning experience. Most of what know I've aquired through forums like this and videos.
Logistics Pro
Joined: Jan 2001
Posts: 3,740
Likes: 37
From: Central NYS
When the PCM sets a DTC, it takes a snap shot of available date and holds it in the “freeze frame” . That freeze frame data lets you know what was going on when the DTC was set. Things like engine coolant temp, rpm, throttle opening, engine load, fuel trims, etc.etc.
Fleet Mechanic
Joined: Jul 2019
Posts: 1,317
Likes: 314
A common cause for this on the previous generation trucks with Triton engines was a rear pvc hose elbow that ran from the passenger side valve cover to the back of the intake right up facing the firewall.
I’d definitely check that hose elbow for any deterioration if it’s still the same design.
I’d definitely check that hose elbow for any deterioration if it’s still the same design.
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7th Gear
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Will do
A common cause for this on the previous generation trucks with Triton engines was a rear pvc hose elbow that ran from the passenger side valve cover to the back of the intake right up facing the firewall.
I’d definitely check that hose elbow for any deterioration if it’s still the same design.
I’d definitely check that hose elbow for any deterioration if it’s still the same design.
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7th Gear
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Follow-Up...
Sorry it's been a while, but thanks for all the help.....here's where I stand.
-Vehicle still seems to be starving to death.
First, a list of things checked:
- All fuses
- Wire connections to insure proper fit
Second, a list of things replaced:
- All 8 coils & plugs
- All 4 O2 sensors
- Mass Airflow Sensor
- EGR valve
- PCV valve
- Fuel Filter
- Timing Chain, guides and tensioner
- Oil Pump
Third, a list of things I know:
- With everything connected and plugged up it idles rough and starts dying the instant you apply throttle.
- If I unplug the MAF sensor, even after installing a new one, it greatly improves and will take the throttle with slight hesitation.
- After installing new parts, and resetting codes, the only codes showing now are "system lean banks 1" & "system lean bank 2". (Not the proper wording, but thats what they mean.)
-Vehicle still seems to be starving to death.
First, a list of things checked:
- All fuses
- Wire connections to insure proper fit
Second, a list of things replaced:
- All 8 coils & plugs
- All 4 O2 sensors
- Mass Airflow Sensor
- EGR valve
- PCV valve
- Fuel Filter
- Timing Chain, guides and tensioner
- Oil Pump
Third, a list of things I know:
- With everything connected and plugged up it idles rough and starts dying the instant you apply throttle.
- If I unplug the MAF sensor, even after installing a new one, it greatly improves and will take the throttle with slight hesitation.
- After installing new parts, and resetting codes, the only codes showing now are "system lean banks 1" & "system lean bank 2". (Not the proper wording, but thats what they mean.)
Last edited by Moonpie1984; Mar 8, 2022 at 02:42 PM.
Logistics Pro
Joined: Jan 2001
Posts: 3,740
Likes: 37
From: Central NYS
Again, codes and freeze frame data can be helpful.
If the PCM sets the P0171/174 at idle or no load it is probably a vacuum leak.
I f freeze frame indicates the code trips at higher rpm and/or load I’d suspect fuel supply.
Where are your fuel trims and what is your fuel pressure?
If the PCM sets the P0171/174 at idle or no load it is probably a vacuum leak.
I f freeze frame indicates the code trips at higher rpm and/or load I’d suspect fuel supply.
Where are your fuel trims and what is your fuel pressure?
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7th Gear
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Again, codes and freeze frame data can be helpful.
If the PCM sets the P0171/174 at idle or no load it is probably a vacuum leak.
I f freeze frame indicates the code trips at higher rpm and/or load I’d suspect fuel supply.
Where are your fuel trims and what is your fuel pressure?
If the PCM sets the P0171/174 at idle or no load it is probably a vacuum leak.
I f freeze frame indicates the code trips at higher rpm and/or load I’d suspect fuel supply.
Where are your fuel trims and what is your fuel pressure?
Not sure of the actual pressure for the fuel, however; i am waiting on a tool i ordered to check that now. Also, I have a better reader on the way that provided live data.
It definitely seems like vacuum issue, but for the life of me I can not track it down.
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