Ask the Car People.SM


Ford Windstar - fixing PO171 and PO174

25 messages,  Last post on Feb 13, 2013 at 11:35 AM

You are in the Ford Windstar Forum.

What is this discussion about? Ford Windstar, Van

Messages Page 3 of 3

#19 of 25 po174 and po 175 nightmares by gec19delta

Mar 28, 2009 (10:25 am)

Replying to: diclemeg (May 01, 2008 6:28 pm)
---------------------------------------------------------------------------------
 
 A Ford P0171 is a LEAN code fpr cylinder bank 1, and P0174 is a LEAN code for cylinder bank 2. These codes commonly occur on many Ford vehicles, and are set when the powertrain control module (PCM) sees the air/fuel mixture is running too lean (too much air, not enough fuel).
 
When the Check Engine Light comes on, either one of these codes, or both, may be found when a code reader or scan tool is plugged into the vehicle diagnostic connector. IF the vehicle is driven long enough, typically both codes will be set.
 
A P0171 lean code for bank 1 is the cylinder bank on the RIGHT (passenger) side of the engine on Ford vehicles with a V6 or V8 engine and rear-wheel drive.
 
A P0174 lean code for bank 2 is the cylinder bank on the LEFT (driver) side of the engine on Ford vehicles with a transverse-mounted V6 engine and front-wheel drive. This code is not set on four cylinder engines (no bank 2).
 
WHAT A LEAN CODE MEANS
 
A lean fuel condition may exist if the engine is sucking in too much air and/or the fuel system is not delivering enough fuel. If bad enough, a lean fuel condition may cause lean misfire, a rough idle, hesitation or stumble when accelerating, and/or poor engine performance.
 
Unmetered air can enter the engine through a vacuum leak, a dirty airflow sensor that is not reading airflow accurately, an EGR valve is not closing and is leaking exhaust into the intake manifold, an EGR valve that is allowing too much flow (because the EGR differential pressure sensor that monitors EGR flow is faulty and is under-reporting EGR flow).
 
If the problem is not enough fuel, the underling cause may be a weak fuel pump, restricted fuel filter, leaky fuel pressure regulator or dirty fuel injectors.
 
DIRTY MAF SENSOR
 
One of the most common causes of Ford P0171 and P0174 lean codes is a dirty mass airflow (MAF) sensor. The MAF sensor is located in the air inlet tube
 just ahead of the throttle body. The MAF sensor should be protected from outside dust and debris by the air filter, but sometimes the air filter doesn't fit real tight inside the housing and allows unfiltered air into the engine. Dirt can stick to the MAF sensor wire and form a coating that slows the response of the sensor to changes in airflow. The MAF sensor can also be contaminated by fuel vapors that back up through the intake manifold and throttle body when the engine is shut off. The vapors can leave a waxy coating on the sensor wire. This causes the MAF sensor to under report airflow, which in turn misleads the powertrain control module (PCM) so it doesn't add enough fuel to maintain a properly balanced air/fuel ratio. As a result, the engine runs lean and sets a P0171 and/or P0174 code (see Ford TSB 98-23-10 for details).
 
If the MAF is dirty, the fix is easy enough: just clean or replace the MAF sensor. In many instances, the MAF sensor can be successfully cleaned by spraying the sensor element with electronics cleaner. Do not use any other type of cleaner as this may damage the sensor.
 
Disconnect the air inlet tube just ahead of the sensor, and then spray the electronics cleaner through the screen at the wire element in the center of the little MAF sensor. Let the cleaner soak in for several minutes, then give it another shot of cleaner. Let it sit another five minutes, then reconnect the air inlet tubing and start the engine.
 
If the lean codes keep coming back, the MAF sensor may have to be replaced if the engine does not have a vacuum leak or fuel delivery problem.
 
VACUUM LEAKS
 
Another common cause of Ford P0171 and P0174 ean codes is an engine vacuum leak. Ford TSB 04-17-4 details procedures for checking fuel trim and looking for vacuum leaks.
 
 On 3.8L Fords with a split-plenum intake manifold, the port gaskets and isolator bolt assemblies for the upper plenum can deteriorate over time and leak air, often as a result of oil being sucked into the intake manifold through the PCV system. Also the vacuum hose that connects the fuel pressure regulator to the intake manifold can swell and leak vacuum where the hose connects to the manifold. Ford TSB 03-16-1 says the fix involves several steps: remove the upper manifold plenum and replace the original gaskets and bolts with revised ones, replace the front valve cover with a revised valve cover that reduces the amount of oil vapor sucked into the PCV system, inspect and replace the fuel pressure regulator hose, and finally, reflash the PCM so it is less sensitive to lean fuel conditions.
 
BAD DPFE SENSOR
 
Ford p0171 AND p0174 lean codes can also be set by a bad EGR differential pressure sensor. These sensors have a very high failure rate once a vehicle has more than about 60,000 miles on the odometer or is more than five or six years old.
 
 The DPFE sensor is mounted on the engine, and is attached with two rubber hoses to the tube that routes exhaust gas to the EGR valve. The original equipment sensor has an rectangular aluminum housing about three inches long. Corrosion inside the sensor reduces its sensitivity to EGR flow, causing it to under-report EGR flow. The PCM responds by increasing EGR flow, which may keep the EGR valve open longer than usual creating a lean condition in the engine. Thus, a bad sensor may set a P0401 code (insufficient EGR flow), or it may not set an EGR code but a P0171 and/or P0174 lean code instead.
 
The cause of the P0401 code in most cases turns out to be a bad DPFE sensor, not an EGR valve problem or an EGR valve that is plugged up with carbon (though this can also set a P0401 code). An aftermarket replacement DPFE sensor costs less than $50 and usually gets rid of not only the P0401 code, but also the P0171 and P0174 codes, too.
   
 
good luck god bless

#20 of 25 Re: po174 and po 175 nightmares [gec19delta] by autodr

Mar 28, 2009 (11:46 am)

Replying to: gec19delta (Mar 28, 2009 10:25 am)
Good write up. Just a few details I'd like to add or change.
 
"A P0171 lean code for bank 1 is the cylinder bank on the RIGHT (passenger) side of the engine on Ford vehicles with a V6 or V8 engine and rear-wheel drive.
  
A P0174 lean code for bank 2 is the cylinder bank on the LEFT (driver) side of the engine on Ford vehicles with a transverse-mounted V6 engine and front-wheel drive. This code is not set on four cylinder engines (no bank 2)."

 
Right/Passenger/Rear... depending on longitudinally mounted (rwd) or transverse mounted (fwd)
 
LEFT/Driver's/Front... depending on mounting.
 
"One of the most common causes of Ford P0171 and P0174 lean codes is a dirty mass airflow (MAF) sensor."

 
"one of" I agree... but probably the most common is a vacuum leak.
 
"If the lean codes keep coming back, the MAF sensor may have to be replaced if the engine does not have a vacuum leak or fuel delivery problem."
 
Careful. What would happen if it had E85 added to the tank? What if someone damaged the inlet screen to the MAF (not sold with a MAF unless you get the entire air cleaner housing). I've also seen some really P-Poor quality air filters (especially go-fast types) cause rich and lean codes because the nose cone is shaped wrong causing a distorted air flow shape through the MAF sensor. No part should be replaced based on the reoccurred of a code because codes don't mean "replace this" or "this part is bad". In the case of a lean or rich code, fuel trim characteristics should be observed, plus BARO reading PID, and/or volumetric efficiency calculations should be made to peg a bad MAF. One common characteristic of a faulty MAF is that the Load% PID and the LTFT PID will follow each other perfectly when graphed out.
 
All of the Ford Plastic intake manifolds have seal issues. I know that old TSB may only mention one style. But a lot has happened since then. Also, on Wind-ed Stars, the lower intake also leaks. Not mentioned in the TSB. The IMRC shaft seals leak vacuum. FoMoCo released a reflash that hides the leak so they didn't have to eat many under warranty. But eventually they leak bad enough there that the lower intake manifold also has to be replaced because they leak beyond what the new software can hide... the actual aluminum manifold.
 
As for the 4cyl engine not having a bank2.... as long as you are talking FoMoCo, then you are right. No FoMoCo 4cyl that I know of... yet... have a bank 2. But, a 4 cylinder in-line engine can have a Bank2. Just look at about a 2002 Nissan Sentra. Cyls 1 and 2 are piped to the B1S1 O2, and the #3 and #4 cyls are piped to the B2S1 O2. Then they have 2 separate Cats (inside a common housing), with a B1S2 cat monitor, and a B2S2 cat monitor. A total of 4 O2 sensors with a bank 1 and bank 2 on an inline 4cyl engine. They are out there Just not in the FoMoCO world.... so you are still in the right.

#21 of 25 2001 ford windstar transmission issues by trounda

Jul 04, 2009 (11:18 am)

i pulled the transmission and replaced torque converter and front seal drove down the road 0/d light started flashing getting this code p1744 please help need this van so my mom can go to work

#22 of 25 Can MAF Icing cause "Lean" codes? by bigredrasa

Jan 29, 2011 (11:28 am)

In the good/bad old days, carburetor icing could cause driveability problems in cold, damp weather. We have had very cold and damp weather in the last month, and I've had the P171 & P174 codes come on twice. After resetting, they stay off for some time. Could ice build up on the MAF Sensor cause the codes? It could explain why they come on only in very cold and damp weather.

#23 of 25 replaced alot still code 174 by kc9kpq

Jan 25, 2012 (8:55 am)

Hi
 New to this forum.I have a 02 windstar. I replaced the isolator bolts gaskets imrc bushings valve stem seals (bank 2 only) valve cover fuel pressure vac line and pcv + vac line. dorman kit 615-177 and still getting the code for bank 2. I was getting bank 1 and 2 before all this. . Odes any body recommend the DPFE, mine is not the metal one mounted near the fuel rail. it is plastic and mounted with short hoses about midway between the egr valve and radiator. also I wonder if I should reflash the pcm (not really happy about Ford charging 100 dollars to fix thier mistake)
 
Thanks in advance

#24 of 25 Same problem same codes 99 windstar FWD 6 cyl by billyzeke

Aug 01, 2012 (4:00 pm)

OK i had these problems since i bought the piece of shit a year ago ! both codes came up when inspected thought i lost papers where i wrote them down but found em ! Was told two sensors were bad and EGR valve ! Problems are bad MPG city maybe 11 MPG surges and kicks when stop at light stalls after idling too long etc... I reset the CE light by disconnecting battery van ran far better after that but of course CE light comes back on after about 15 - 20 mins driving !
 
SAW the last answer and i agree has to be in the exhaust or air intake thingy I did spot crack in housing fixed it , and it didnt close too good ! Also fixed that ! I also presume a vacumm leak some where is the problem !
SO after i fix or cannot find a vacumm leak or it's not the air filter housing what do i need to replace That MAF thing or The EGR valve and that too ? I get good used parts at yard where you pull it off maybe cost $15 - $35 tops ! IF they don't work then i go good ol pep boys and get the best priced ones ! I need this van to go another year because I make money with it ! It has 198,000 on it right now only major problem i had was starter went kaput when coming out of Home depot LOL Got it started by rocking van and turning key ! BUT next day wouldnt start 2nd time and had to tow it in total cost lifetime starter $340
 
Has other wacko problems electrical but somehow they just start working right again ! THIS is MY last FORD product ever ! Had EM all Mercury Lincolns etc .. each one lived up to it's name FIXED OR REPAIRED DAILY back words DRIVER RETURNS ON FOOT ! LOL

#25 of 25 Re: fixing PO171 and PO174 [dmdkana] by kendermo

Feb 13, 2013 (11:35 am)

Replying to: dmdkana (Mar 26, 2008 5:21 pm)
DIRTY MAF SENSOR fixed my errors. It's easy and cheap, try it first. Buy a can of MAF cleaner, spray it on. Hardest part is loosening the darned gigantic air filter and reconnecting it (this used to be so easy!) Broke 2 fingernails doing this and got my hands dirty. I hate this vehicle!! Simple things are such a pain on it.

Messages Page 3 of 3

To POST a message, please Sign In.

Advertisement

Browse by Category

Browse by Vehicle
   View All Vehicles

Browse by Board
Browse by Topic
View All Topics

Edmunds Community

Advertisement