P0171 code - Ranger-Forums - The Ultimate Ford Ranger Resource

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

LinkBack Thread Tools Search this Thread
Old 06-14-2012
CIB-11B's Avatar
Thread Starter
Join Date: Feb 2012
Location: Central Point, Oregon
Posts: 88
P0171 code

2003 Ranger 4.0, 203k. CEL on, checked with code reader and got a P0171 code, lean condition in bank 1. I know what the possible causes are, but I checked spark on bank 1 and it is very weak. To me a weak spark would cause a rich condition not a lean one, all 3 plugs on bank 1 were weak. Is the PCM trying to compensate for the lean condition by dropping spark to try to fatten it back out on that side? Or is there some magical way that weak spark is causing the lean condition? Maybe the weak spark is only igniting partially and the part that is left over is lean, causing the O2 sensors to read it as lean? I'm stumped, any ideas?
Reply With Quote
Old 06-18-2012
CIB-11B's Avatar
Thread Starter
Join Date: Feb 2012
Location: Central Point, Oregon
Posts: 88
No insight from the super gurus?
Reply With Quote
Old 01-21-2013
Join Date: Mar 2010
Location: Roy, Utah
Posts: 25
Your logic seems good if you have the cause and effect correctly figured. What if the cause is weak spark so the PCM leans out the bank in order to get ignition. I guess I am saying this to get you to go after the lean condition, since the trouble code says that's the problem. Once fixed, if you are correct in your thinking, the weak spark will than be adjusted and not be a problem. Go for the likely causes: air infiltration or lack of fuel to that bank. Good luck.
Reply With Quote
Old 01-22-2013
john93rangerstx's Avatar
Join Date: Mar 2008
Location: WARWICK RI
Posts: 895
replace the o2 and you will be fine 90% sure of it that a commin code
Reply With Quote

Related Topics
Thread Thread Starter Forum Replies Last Post
P0171 Code. . .need a little help chevyslayer925 4.0L OHV & SOHC V6 Tech 25 05-14-2011 07:32 PM
P0171 code nek396 General Technical & Electrical 2 10-26-2010 04:13 PM
cel p0171 and p0174 tspoon General Technical & Electrical 6 12-07-2008 11:19 AM
P0171 - system too lean rellim_63 SOHC - 2.3L & 2.5L Lima Engines 15 03-17-2008 06:37 AM
p0171 and p0174 rdy4mud General Technical & Electrical 13 02-20-2008 12:17 PM

Thread Tools Search this Thread
Search this Thread:

Advanced Search

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

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

All times are GMT -6. The time now is 11:32 PM.

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.