Replaced Engine now have po171 code - Ranger-Forums - The Ultimate Ford Ranger Resource
Ford Ranger Forum - Forums for Ford Ranger enthusiast!

Go Back   Ranger-Forums - The Ultimate Ford Ranger Resource Arrow Ranger-Forums Technical Engine Forum Arrow 2.9L & 3.0L V6 Tech

2.9L & 3.0L V6 Tech General discussion of 2.9L and 3.0L V6 Ford Ranger engines.

LinkBack Thread Tools Search this Thread
Old 07-20-2016
Thread Starter

Join Date: Jul 2016
Vehicle: 2004 FORD RANGER
Drive Type: 4X2
Engine: 3.0
Posts: 1
Total Props: 0
Replaced Engine now have po171 code

2004 Ranger Edge 3.0 156,000 miles - I helped my step-son put a reman engine after the cam synch shaft went out. Not being too familiar with this set up I(we) didn't know what the alignment tool that came with the new shaft was for and it got lost/ thrown away during clean up after engine install. Anyway got it in and running but runs rough with po171 lean bank 1 code. Here's what I've tried :

brought #1 cylinder up and aligned tab on shaft to center of opening on shaft housing. It was off about 90 degrees from where I had thrown it in but didn't help ran the same.

Checked exhaust manifold temp to narrow down cylinder was the issue, found cylinder #1 had low temp compared to others so started there. With it running pulled wire off the injector which made no change so checked injector pulse with a noid which lit up so that lead me to think bad injector. Replaced it with no change. Tried pulling wire from #3 and engine ran worse so moved to #5 and pulled wire with no change. Moved new injector from #1 to #3 and #1 still made no change when pulling wire off and #3 did again.

The other possibility I understand is that there's an intake leak.

We also replaced the coil we found was bad after the new engine install.

What can I do/ check before pulling the intake?
Reply With Quote
+ 0 -
Old 07-20-2016
iTrader: (1)
I am: Ron Dean
Join Date: Jan 2014
Location: Vancouver, BC
Vehicle: 1994 Ford Ranger
Drive Type: 4x4
Engine: 4.0
Posts: 4,746
Total Props: 88
Welcome to the forum

Lean on one bank/side of an engine means computer is opening injectors on that side more than it "thinks" it should from the air flow it is getting from the MAF sensor.

O2 sensors read oxygen level in the exhaust, too much oxygen means Lean too little means Rich.
So O2 sensor on Bank 1 was showing too much oxygen in the exhaust, so computer added more fuel and it still show too much oxygen so computer added more fuel, and...........
Computer continues to add more fuel and then reaches a preset number at which time it will set the Lean code for that bank, it continues to add more fuel.
The CEL and code are to give the driver a "heads up" that something is wrong.

The misfire means no oxygen was burned in that cylinder so it all got dumped into the exhaust, and that in itself can cause the Lean code.

Easiest way to check fuel injectors is to unplug the coil pack wires and crank the engine a few times then pull out spark plugs, dry one would be suspect for injector issue.

For lower vacuum leak start with cold engine.
Loosen and remove fan belt from crank pulley
Start engine
Spray Quick Start or Carb cleaner around lower intake and fuel injectors on that side.

Also check upper intake, both banks could be close to pre-set limit for Lean code but only one bank is over it.

You can run a cold engine for 2 minutes without water pump or alternator, but no more or it could over heat.
Running engine without fan blowing makes things much easier.

Cam synchronizer is timed with #1 cylinder at COMPRESSION stroke Top Dead Center, so you can't just put crank on TDC mark, this is a 4-stroke engine so each cylinder has two TDCs, compression and exhaust.
So to time the synchro unit you need to make sure which TDC #1 is on

Last edited by RonD; 07-20-2016 at 04:46 PM.
Reply With Quote
+ 0 -

Similar Threads
Thread Thread Starter Forum Replies Last Post
Fix for Check Engine light codes: p0401, po171 and po174 TheBearJeweler General Ford Ranger Discussion 66 02-05-2013 08:54 AM
what is going on getting a code for parts i replaced after i replaced another part 894banger General Ford Ranger Discussion 4 05-11-2011 08:45 PM
replaced the door lock actuator - now I have a problem doogster General Technical & Electrical 0 04-20-2011 05:18 AM
Thermostat replaced. Coolant leak and now I have a squeak feh728 2.9L & 3.0L V6 Tech 1 11-03-2010 08:08 AM
2003 3.0L - To Those Who Still Have Fan Clutches & Have Replaced Yours Already (pics) HELMUT RONER 2.9L & 3.0L V6 Tech 41 06-21-2009 07:03 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 On
Pingbacks are On
Refbacks are On

All times are GMT -6. The time now is 03:00 PM.