5.4 threw code p0171 and p0174 help?
Junior User
Joined: Nov 2003
Posts: 87
Likes: 0
From: Ohio
My 4.6 started that after I put the high flow throttle body and air filter on it. The computers on these trucks will adapt to changing engine conditions, such as both banks lean, and will compensate for any mods you have done. That being said, you may need an adjustable fuel pressure regulator or bigger injectors. I need to do one of the two because my truck pings on anything under midgrade. Just take it to autohell or someplace and get the light reset. It may take a couple three times, but the computer will eventually adjust. At least that's what the parts manager at the local stealership told me when I asked about injectors or something.
Senior User
Joined: Feb 2005
Posts: 414
Likes: 0
From: Southwestern Pa.
Originally Posted by bigg matt
it says left bank and right bank running lean...what should i do and has anyone ever had this problem...thx
- In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
- Inspect all vacuum and PCV hoses, replace if necessary
- Check for a dirty fuel filter and proper fuel pressure
Senior User
Joined: Mar 2003
Posts: 306
Likes: 0
From: Rancho Cucamonga, CA
Its a bad Mass Air Flow Sensor. We just had the exact same problem on our 98 navigator with a 5.4 (same codes) Cleaning it didnt help. The new MAF sensor from autozone was $89 with core exchange and it fixed our problem.
Hotshot
Joined: Jan 2004
Posts: 19,768
Likes: 1,082
From: St Louis
The most common cause of P0171 and P0174 codes together is due to a vacuum leak, not the MAF or any other sensor.
The most common reason on these trucks is that cheap-*** vacuum elbow located on the PCV tube that runs around from the passenger-side valve cover back around behind the engine where it connects to the intake next to the IAC.
If the elbow is bad, you can pick up a replacement tube with elbow at the Ford dealer (they'll have plenty in stock) or you can replace the elbow itself. Someone posted awhile back that they used a simple 90-degree spark plug boot as a satisfactory replacement...
Steve
The most common reason on these trucks is that cheap-*** vacuum elbow located on the PCV tube that runs around from the passenger-side valve cover back around behind the engine where it connects to the intake next to the IAC.
If the elbow is bad, you can pick up a replacement tube with elbow at the Ford dealer (they'll have plenty in stock) or you can replace the elbow itself. Someone posted awhile back that they used a simple 90-degree spark plug boot as a satisfactory replacement...
Steve
Thread Starter
|
New User
Joined: Mar 2005
Posts: 5
Likes: 0
checked and sprayed all vaccuum line with no leaks. everything checked out. i reset the light with a scanner tool 3 times but it keeps coming back on. i will clean the maf sensor and see if that helps-if it doesnt i will replace it...any other info? thx a bunch
Trending Topics
Senior User
Joined: Feb 2005
Posts: 131
Likes: 0
Also check all the vacuum lines that run up against the firewall and have a elbow that connects to the back of the throttle body. Also, change your fuel filter and clean your fuel injectors.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 6 Best Deals Available on New Fords & Lincolns Right Now
Brett Foote
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level
Verdad Gallardo
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
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
Thread
Thread Starter
Forum
Replies
Last Post
msradio
1997 - 2006 Expedition & Navigator
2
Jan 22, 2013 08:16 AM
Roushians
Ford Inline Six, 200, 250, 4.9L / 300
2
May 6, 2005 09:07 AM