Too Lean Codes
Thread Starter
|
New User
Joined: Jun 2019
Posts: 5
Likes: 0
Too Lean Codes
Running 218K on my 2005 F-150. Error codes are three Too Lean, P0171 (Bank 1) and a pair of P0174 (both on Bank 2).
In last nine months, have cleaned MAF sensor multiple times, and replaced it for second time in less than four years. Truck also developed a real bad habit of stalling out at idle while in drive (at the long red light, in other words), though that has not happened in more than two months. Fuel efficiency, particular on city, has flattened out. Highway mileage is still not too bad.
Is this the 02 sensors? To be clear, the lights only came on in the last month.
In last nine months, have cleaned MAF sensor multiple times, and replaced it for second time in less than four years. Truck also developed a real bad habit of stalling out at idle while in drive (at the long red light, in other words), though that has not happened in more than two months. Fuel efficiency, particular on city, has flattened out. Highway mileage is still not too bad.
Is this the 02 sensors? To be clear, the lights only came on in the last month.
FTE Community Team
Joined: Jan 2019
Posts: 10,769
Likes: 1,506
Remember, vacuum is highest with throttle plates closed . . . and the engine is not as easily able to deal with the extra air (coming in through a vacuum leak) at idle, which is at the bottom of its operating range. While driving on the highway, there is less vacuum to draw air in, and at the same time there is more air and fuel going through and what little air gets leaked in is easily digested without issues.
While we're here: How many miles are on the current set of spark plugs?
While we're here: How many miles are on the current set of spark plugs?
Thread Starter
|
New User
Joined: Jun 2019
Posts: 5
Likes: 0
Is that the little vacuum tube that runs immediately in front of the cab? I replaced that around 2014.
Thread Starter
|
New User
Joined: Jun 2019
Posts: 5
Likes: 0
Remember, vacuum is highest with throttle plates closed . . . and the engine is not as easily able to deal with the extra air (coming in through a vacuum leak) at idle, which is at the bottom of its operating range. While driving on the highway, there is less vacuum to draw air in, and at the same time there is more air and fuel going through and what little air gets leaked in is easily digested without issues.
While we're here: How many miles are on the current set of spark plugs?
While we're here: How many miles are on the current set of spark plugs?
FTE Community Team
Joined: Jan 2019
Posts: 10,769
Likes: 1,506
I wonder why they weren't all replaced at the same time?
Trending Topics
Thread Starter
|
New User
Joined: Jun 2019
Posts: 5
Likes: 0
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
Fleet Mechanic
Joined: Apr 2016
Posts: 1,653
Likes: 193
You have different vacuum tubes running around the truck. One can be the 4x4 iwe source,another is the pcv sytem ,one on the fuel rail pressure sensor, one on the evap system , brake booster . Any gasket or crack on intake manifold etc .
So you see where a homemade smoke machine off you tube comes into play .And using torque pro you can look at 02's and see if they are responding/ switching at idle and 2500rpm .I finally built my own little smoke machine . My wifes explorer had been acting up for a year and my mech did not have one.Second try smoke came up from under battery ,purge solenoid hidden there $29 bucks later it was fixed . Plastic had dissolved from alcohol in gas
Another friend had a van that had been connected to there different s.machines luckily it was on a lift and he saw a little puff from gas tank . Gas tank gasket folded at factory installation causing problem . when system pulls small vac on fuel system to check integrity.
Yes it does sound like a vac leak .
Good luck
So you see where a homemade smoke machine off you tube comes into play .And using torque pro you can look at 02's and see if they are responding/ switching at idle and 2500rpm .I finally built my own little smoke machine . My wifes explorer had been acting up for a year and my mech did not have one.Second try smoke came up from under battery ,purge solenoid hidden there $29 bucks later it was fixed . Plastic had dissolved from alcohol in gas
Another friend had a van that had been connected to there different s.machines luckily it was on a lift and he saw a little puff from gas tank . Gas tank gasket folded at factory installation causing problem . when system pulls small vac on fuel system to check integrity.
Yes it does sound like a vac leak .
Good luck
Hotshot
Joined: Jan 2004
Posts: 19,763
Likes: 1,081
From: St Louis
And you never will unless the leak is HUGE.
My usual method is to set up the scanner to graph the upstream O2 voltages, run the engine at idle and spray suspect areas with brake cleaner and watch for a response from the sensors. When the spray hits a vacuum leak, the response from the sensor is almost immediate.
My usual method is to set up the scanner to graph the upstream O2 voltages, run the engine at idle and spray suspect areas with brake cleaner and watch for a response from the sensors. When the spray hits a vacuum leak, the response from the sensor is almost immediate.
Thread
Thread Starter
Forum
Replies
Last Post
Paul Comeau
Escape & Escape Hybrid
2
May 28, 2019 07:35 AM