4.0L OHV & SOHC V6 Tech General discussion of 4.0L OHV and SOHC V6 Ford Ranger engines.

P0171 System Lean (Bank 1), Knocking, Low Idle

  #1  
Old 04-30-2009
Member
Thread Starter
Join Date: Jul 2007
Location: Snellville, GA
Posts: 5
Icon5 P0171 System Lean (Bank 1), Knocking, Low Idle

I recently failed my emissions with a P0171 code. I know this could be a lot of things, but there are some other symptoms that go along with the problem.

My engine has a faint knocking that sounds like a misfire. I tried higher octane gas and the sound kept on.

I idle rough down at 500-600 rpm's, and have stalled in the past. I changed the fuel filter and that helped with the stalling, but there is still some occasional hesitation. Once I get going it runs great, but my fuel mileage is down to 15-16 MPG highway.

I cleaned the MAF and throttle body tonight, but I am sure there is more to all this. I am going to get a new hose for my PCV valve because it seems to fit over the valve pretty loose.

What else do I need to do?

Also, I disconnected the neg. terminal to take off the MAF and of course the CEL went off and the code is cleared. How long or far do I have to drive before I know whether or not the problem is fixed?

I know I'm throwin' a bunch at y'all, and I appreciate any feedback.

Thanks.
 
  #2  
Old 05-01-2009
Member
Join Date: Jun 2004
Location: Orange City, FL
Posts: 1,601
you should reall learn to use the search feature on this forum.

p0171 is a lean on bank one, most often caused by a vacuum leak somewhere. Go check all your hoses for crack/dry rot or leaks/holes.
 
  #3  
Old 05-01-2009
01_ranger_4x4's Avatar
Member
iTrader: (4)
Join Date: Mar 2009
Location: Muskegon, Michigan
Posts: 3,585
Originally Posted by PickupMan92 View Post
you should reall learn to use the search feature on this forum.

p0171 is a lean on bank one, most often caused by a vacuum leak somewhere. Go check all your hoses for crack/dry rot or leaks/holes.
X2
 
  #4  
Old 05-01-2009
NVRDONE's Avatar
Member
iTrader: (2)
Join Date: Feb 2009
Location: Union, NJ
Posts: 114
Get a can of carb cleaner and while the truck is running spray some on the vacumme lines, one at a time. If the idle picks up then right where you sprayed is your leak.
 
  #5  
Old 05-01-2009
Member
Join Date: Jun 2004
Location: Orange City, FL
Posts: 1,601
Personally... I wouldn't go around spraying carb cleaner all over a hot motor... I'd go more for the soapy water and look for bubbles.
 
  #6  
Old 05-01-2009
NVRDONE's Avatar
Member
iTrader: (2)
Join Date: Feb 2009
Location: Union, NJ
Posts: 114
Originally Posted by PickupMan92 View Post
Personally... I wouldn't go around spraying carb cleaner all over a hot motor... I'd go more for the soapy water and look for bubbles.

Well no, you dont do it hot. I figured everyone would have figured that out. Best time to do it is first thing in the am after the high idle has calmed down.
 
  #7  
Old 05-01-2009
Member
Join Date: Jun 2004
Location: Orange City, FL
Posts: 1,601
I had to say it lol Can't ever tell with people on here haha.
 
  #8  
Old 02-01-2018
Join Date: Jul 2017
Location: Montrose, PA
Posts: 71
Originally Posted by PickupMan92 View Post
Personally... I wouldn't go around spraying carb cleaner all over a hot motor... I'd go more for the soapy water and look for bubbles.
I know this thread is many years old, just thought I'd add a note for newbies that soapy water does not make bubbles when there is vacuum in a line. That's negative pressure and if there are bubbles the bubbles are getting sucked into the line. Soapy water is for positive pressure, like leaks in compressed air systems or natural gas & propane piping.

Unless I'm full of crap here. If that note's wrong, someone tell me how!
 
  #9  
Old 12-13-2018
Join Date: Dec 2018
Location: Swanzey NH
Posts: 9
Originally Posted by Sparky-WIshItWas View Post
I know this thread is many years old, just thought I'd add a note for newbies that soapy water does not make bubbles when there is vacuum in a line. That's negative pressure and if there are bubbles the bubbles are getting sucked into the line. Soapy water is for positive pressure, like leaks in compressed air systems or natural gas & propane piping.

Unless I'm full of crap here. If that note's wrong, someone tell me how!

no you're good. In order to use the soapy water method, you have to disconnect the vacuumsystem and pressurise it from an outside source.( i.e. air compressor. )
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
RangerJeff420
DOHC - 2.3L Duratec / Mazda L Engines
2
02-25-2011 08:06 PM
j99ranger4x4
4.0L OHV & SOHC V6 Tech
46
05-28-2010 10:29 PM
bryanjints
4.0L OHV & SOHC V6 Tech
21
12-19-2009 11:39 AM
rellim_63
SOHC - 2.3L & 2.5L Lima Engines
15
03-17-2008 05:37 AM
acxlt01ranger4x4
4.0L OHV & SOHC V6 Tech
4
06-24-2006 06:52 AM


Thread Tools
Search this Thread
Quick Reply: P0171 System Lean (Bank 1), Knocking, Low Idle


Contact Us - Sitemap - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.