Ford Truck Fanatics

Home Forum Gallery TOTM Links Sponsors Calendar Arcade Calculators
Go Back   Ford Truck Fanatics > General Maintenance, Performance, and Tech. Info > Certified Ford Tech Help Forum
Register FAQ Members List Search Today's Posts Mark Forums Read My Threads / My Replies Fliers

Find us on Facebook


Certified Ford Tech Help Forum Got a mechanical problem or question about your Ford Truck? Post it here for answers.


Welcome to the Ford Truck Fanatics forums.

You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact us.

Login for fewer ads.

Reply
 
Thread Tools Display Modes
  #1  
Old 02-16-2008, 01:15 PM
rowdy51 rowdy51 is offline
 

Join Date: Feb 2008
Location: Tn
Posts: 5
rowdy51 is on a distinguished road
codes 172,174; banks 1 & 2 running lean

my 1998 F-150, with 4.2 V6 has these codes from time to time; they always seem to come on when slowing to stop; have researched these codes and know what all will turn the check engine lite on; but I can't seem to find out what it actually is; I live in one of the counties where my vehicle has to pass emissions test in order to buy tags for it; plus, I just want my venicle running right; any and all help is appreciated; are there any common problems with this condition;
Reply With Quote
Sponsored Links
  #2  
Old 02-16-2008, 04:48 PM
blacksnapon's Avatar
blacksnapon blacksnapon is offline
Moderator

Moderator
 

Join Date: Feb 2007
Location: waynesville,mo.
Posts: 8,865
blacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond repute
Quote:
Originally Posted by rowdy51 View Post
my 1998 F-150, with 4.2 V6 has these codes from time to time; they always seem to come on when slowing to stop; have researched these codes and know what all will turn the check engine lite on; but I can't seem to find out what it actually is; I live in one of the counties where my vehicle has to pass emissions test in order to buy tags for it; plus, I just want my venicle running right; any and all help is appreciated; are there any common problems with this condition;
P0172, P0171, P0174 AND P0175: FUEL SYSTEM AT THE CORRECTED FUEL TRIM
Diagnostic Trouble Codes (DTCs) P0171 bank 1 (Cylinder 1) and DTC P0174 bank 2 indicate the fuel/air ratio is too lean. The fuel trim system is at the rich correction limit.

DTC P0172 bank 1 and DTC P0175 bank 2 indicate the fuel/air ratio is too rich. The fuel trim system is at the lean correction limit.

DTCs HO2S Reference list:

HO2S-11 = DTCs P0171 and P0172
HO2S-21 = DTCs P0174 and P0175
Possible causes:

Fuel system

Excessive fuel pressure.
Leaking fuel injector(s).
Leaking fuel pressure regulator.
Low fuel pressure or running out of fuel.
Contaminated fuel injector(s).
Vapor management valve (VMV) leaking.
Induction system

Air leaks after the MAF.
Vacuum leaks (vacuum lines and gaskets).
Restricted air inlet.
PCV system.
Fuel purge system.
Improperly seated engine oil dipstick.
EGR System

leaking gasket.
Stuck open EGR valve.
Leaking diaphragm.
Base engine

Oil overfill.
Cam timing.
Cylinder compression.
Exhaust leaks before or near the HO2S(s).
Check intake air system for leaks, obstructions and damage.
Check air cleaner element, air cleaner housing for blockage.
Verify integrity of the PCV system.
Check for vacuum leaks.
__________________
ase master tech--fmc senior master tech
Reply With Quote
  #3  
Old 02-19-2008, 10:47 AM
jbish28's Avatar
jbish28 jbish28 is offline
former Ford Master Tech
 

Join Date: Feb 2008
Location: Iowa
Posts: 18
jbish28 is on a distinguished road
There are a lot of contributing factors to your issue. Without knowing what kind of scan tool you are using it is hard to say. If I encountered this problem with a customer vehicle I would be looking at o2 sensors, maf sensor, fuel trim and bare data to see why the ecu is correcting to lean. Those codes are telling you that know how much fuel the ecu commands, it cannot get it rich enough. Check for vacuum leaks by spraying some carb cleaner around the intake and all the vacuum lines. Also spray it near your pcv hoses. Check for a fuel restriction with a fuel pressure gauge WHILE driving. Check your connections at the mass airflow sensor and also your fresh air ducting to make sure it is installed properly. Perhapstake the maf sensor off and inspect the wires to be sure there is no debris. after all that if you still have a problem write back.
Reply With Quote
  #4  
Old 03-08-2008, 10:16 AM
rowdy51 rowdy51 is offline
 

Join Date: Feb 2008
Location: Tn
Posts: 5
rowdy51 is on a distinguished road
using the SunPro scan tool; my mistake on earlier post; codes are 171, 174; changed the elbow under t-body; but didn't help; ( a friend at work had same thing on his 99, it fixed his problem took it easy on my driving for a few days, shifting to neutral every time I stopped; finally got enough drive time on comp to pass emissions testing and got new tags; seems like the codes come in when I am slowing down for a complete stop; this had happened 2 times before and I changed O2 sensore both times and it lasted about 12-14 months before happening again; I tee-ed off the vac line going to the VMV, it was reading about 17" vac; can clamp off this same vac line and vac goes up to about 19 1/2" vac; what kind of vac should I see on engine setting running idle; engine is not running rough at idle; I do appreciate all your help;
Reply With Quote
  #5  
Old 03-08-2008, 10:18 AM
rowdy51 rowdy51 is offline
 

Join Date: Feb 2008
Location: Tn
Posts: 5
rowdy51 is on a distinguished road
the vac lines and system are very difficult to get to, plus I have to work outside, so it had been very slow working on it, depends on weather;
Reply With Quote
  #6  
Old 03-08-2008, 10:23 AM
blacksnapon's Avatar
blacksnapon blacksnapon is offline
Moderator

Moderator
 

Join Date: Feb 2007
Location: waynesville,mo.
Posts: 8,865
blacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond reputeblacksnapon has a reputation beyond repute
From this point, its going to involve detective work on your part. Pay attention to my earlier post, and jbish's post. In there is your answer. Lean conditions are never easy. Best of luck.
__________________
ase master tech--fmc senior master tech
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump



All times are GMT -5. The time now is 09:03 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Ford Truck Fanatics is not affiliated with or endorsed by Ford Motor Company.