Rob Whaley
New Member
My 03 Expedition is showing code PO171 and bank 1 is too Lean. any suggestions?
Service Engine Code
- Thread starter Rob Whaley
- Start date
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docraymund
Full Access Members
Get yourself a bluetooth OBD 2 reader and download the Torque app on an Android phone. It has a graphing function. Choose long term fuel trim bank 1. With the engine warmed up, rev the engine to 2500 rpm. If the LTFT bank 1 drops, you have a vacuum leak.
stamp11127
Full Access Members
Welcome to the site.
The pcm is already detecting a lean condition so there isn't a true need to verify it. Usual suspects are the intake manifold gaskets or if you have a plastic manifold those will crack with age. You can use a can of carb clener and spray the gaskets and hoses. If it pulls some in the engine will speed up slightly. Do this with the engine at idle. Don't spray a hot egr or things will get exciting.
At the age of the vehicle it would be worth investing a little time inspecting the vac lines - you will later anyway.
The pcm is already detecting a lean condition so there isn't a true need to verify it. Usual suspects are the intake manifold gaskets or if you have a plastic manifold those will crack with age. You can use a can of carb clener and spray the gaskets and hoses. If it pulls some in the engine will speed up slightly. Do this with the engine at idle. Don't spray a hot egr or things will get exciting.
At the age of the vehicle it would be worth investing a little time inspecting the vac lines - you will later anyway.
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