Mil - P0171 + P0174

Arsalan Manager Washington, District of Columbia Posted   Latest   Edited  
Question
Emissions
2004 Ford Explorer Eddie Bauer 4.6L (W) 5-spd (5R55S)—1FMZU74W54UB29946
Check Engine Light - P0171 & P0174

Hello.

I have this vehicle at my shop and giving me a big headache now and starting getting to the point where I feel like I'm starting to spend money from my pocket.

It have check engine light with DTC P0171 & P0174.

STFT B1 : +12

LTFT B1 : +25

STFT B2: +7

LTFT B2 : +25

Replaced Items

  • MAF Sensor, Both Upstream Oxygen Sensor, EGR Valve, Fuel Pump, Intake Manifold Gaskets, PCV Valve & Hoses (All Motorcraft Items). I checked for vacuum leaks on cold engine erly in the morning but did not find anything.

PLEASE HELP

0
Eri Technician
Larchmont, New York
Eri
 

Perhaps you should let us know when the fuel trims are lean (idle,2500,under load). what vehicle? What tests have you Done? Etc...

0 Ð Bounty Awarded
Arsalan Manager
Washington, District of Columbia
Arsalan
   

Fuel Trims at idle STFT B1 : +12 LTFT B1 : +25 STFT B2: +7 LTFT B2 : +25 If I rev the engine and hold at 2500 RPM then LTFT come down and STFT rises to around +25

0 Ð Bounty Awarded
Chris Technical Support Specialist
Commack, New York
Chris
   

With trims being lean both at idle and off idle, I do not suspect a vacuum issue What is the MAF reading at idle? Have you measured fuel pressure?? Have you performed an Ethanol / Water separation test on the fuel?

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Arsalan Manager
Washington, District of Columbia
Arsalan
 

Hello Chris. I have check the entire system properly for leaks and I did not found anything. (Cold Engine). I have also checked the fuel pressure and made sure pressure do not drop after turning the key off. MAF Sensor is also new but I'll get the reading in few seconds and post it here for you. Thank You

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Albin Diagnostician
Leavenworth, Washington
Albin
 

Herein lies your problem, you are out looking and searching for the problem. If you would let your scan data lead you to the problem, life would be a lot easier. If you would like me to explain how this can be done, I would be glad to do it. You will need a scan tool that will make a data capture and can display the data pids in a graph. Let me know, and I'll try to help you do this job the

+2 Ð Bounty Awarded
Arsalan Manager
Washington, District of Columbia
Arsalan
 

Hello Albin. Can you please help me with this problem because I'm starting to pull my hair from head.

0 Ð Bounty Awarded
Albin Diagnostician
Leavenworth, Washington
Albin
 

Here are two different posts I have put up here on DN about this subject. Read them over and get back to me with your questions. You can give me a call if needed … diag​.​net/msg/m6dd30cz5z… diag​.​net/msg/m385mqlbos…

+2 Ð Bounty Awarded
Martin Diagnostician
Burleson, Texas
Martin
 

I agree with Albin. We need to see data as it is trending in a graph. Read the links he posted. It is great information.

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Albin Diagnostician
Leavenworth, Washington
Albin
 

diag​.​net/msg/m61bqk58h6…

+1 Ð Bounty Awarded
Chris Diagnostician
Commack, New York
Chris
 

Can you please supply year, make, model, and engine size?

0 Ð Bounty Awarded
Arsalan Manager
Washington, District of Columbia
Arsalan
 

I'm sorry. Its 2004 Ford Explorer 4.6L Eddie Baur.

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Arsalan Manager
Washington, District of Columbia
Arsalan
 

2004 Ford Explorer with 4.6L

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Edward Owner/Technician
San Antonio, Texas
Edward
   

Hi there Arsalan have you check this TSB out

0 Ð Bounty Awarded
Arsalan Manager
Washington, District of Columbia
Arsalan
 

Hello Edward. I did check this TSB while I was talking to the tech on identifix hotline. We did the injector pulse test and all test out okay with same specs.

0 Ð Bounty Awarded
Edward Owner/Technician
San Antonio, Texas
Edward
 

Whats the drivability of the vehicle when driving beside the check engine light on.....

0 Ð Bounty Awarded
Arsalan Manager
Washington, District of Columbia
Arsalan
 

Vehicle drives normal. Can't even notice any problems that how it drives. Only concern is that customer do not like to see check engine light on dash.

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Chris Technician
Bryans Road, Maryland
Chris
 

Hello! Was the fuel filter replaced with the fuel pump? Was the condition of the fuel check ? Do you have anyway to check to make sure you are getting the correct volume of fuel? Chris

0 Ð Bounty Awarded
Arsalan Manager
Washington, District of Columbia
Arsalan
 

Hello Chris. Yes I did replace fuel filter. Fuel pressure on gauge I'm reading is about 63psi and drops to 55 after shutting down the vehicle for 10 min. And volume is fine aswell.

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Chris Technician
Bryans Road, Maryland
Chris
 

Did you compare a fuel sample to a new fuel sample? Maybe water or to much ethanol or other contaminates.

0 Ð Bounty Awarded
Arsalan Manager
Washington, District of Columbia
Arsalan
 

Hello Chris. Yes I did do the fuel sample test and also I checked for ethonal while I was talking to the identifix on hotline. It test out to be okay and he also made me remove all the fuel out and add fresh fuel in there but we still have the same issue. Identifix also made me replace PCM and program but still same issue.

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Matt Diagnostician
Red Wing, Minnesota
Matt
 

diag​.​net/msg/m4gmsw4z9h…

-1 Ð Bounty Awarded
Sherwood Owner/Technician
St. Marys, Georgia
Sherwood
 

Have you done a VE test? If so, what are the readings and how exactly did you perform the test? We have to look at this logically - both banks are running lean and they are lean at idle and off idle. This would rule out anything that affects only one bank and anything that would only affect fuel trims at low or high rpm (O2 sensors and vacuum leaks) and we would need to concentrate only on

+2 Ð Bounty Awarded
Arsalan Manager
Washington, District of Columbia
Arsalan
 

Hello. I have not done the VE test. My MAF Sensor reading at idle is 4.74 (gm/S) & 0.98V (2500 RPM readings are 16.85 gm/S & 1.77V)

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Chris Technical Support Specialist
Commack, New York
Chris
 

Were all of these parts for this issue or have we already repair some other concerns? Make sure the air filter is the right filter, the V6 filter is shorter and will fit in the airbox. This can skew MAF readings.

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Arsalan Manager
Washington, District of Columbia
Arsalan
 

YES all of these parts were replaced because of DTC P0171 & P0174. I checked the air filter its about 2 months old and looks good and correct part and size.

0 Ð Bounty Awarded
James Owner/Technician
Brook, Indiana
James
 

How did you check your fuel volume, do you have a fuel volume guage?

0 Ð Bounty Awarded
Arsalan Manager
Washington, District of Columbia
Arsalan
 

Hello James. Customer needs to talk to his personal mechanic first, Because I have told him to drop the vehicle to my shop for proper diagnostic. He was wasting too much of his money by listening to someone else who calls himself a mechanic. Will come back and update with more info once he drop off the vehicle

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Ryan Owner/Technician
New Milford, New Jersey
Ryan
 

Good afternoon please perform volumetric effecicency test and post results. I think this will lead us in the correct direction!!

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Glenn Owner/Technician
New Sharon, Maine
Glenn
 

I had same issue on a honda pilot today. Clogged fuel injectors. I performed wynn's cleaning but same problem. Rreplaced injectors and fuel trim returned to normal. If stft is lean at idle and above idle suspect fuel issue. If pressure is good and fuel not contaminated probably injector issue.

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Arsalan Manager
Washington, District of Columbia
Arsalan
 

Hello Ryan. I will let the customer know about this test. He bring vehicle to me every two days after talking to his personal so called mechanic

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Geoff Diagnostician
Lahaina, Hawaii
Geoff
 

Were you able to get decent history, per chance? I'm wondering about things like: Did the car just suddenly "do it" after years of trouble free operation?, or did they just buy it (like this). e.g. I'm thinking if the injectors aren't simply old and evenly clogged, they could even be wrong for the application, if someone has "been in there" before the truck came to you. No need to respond…

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Daryll Diagnostician
Seymour, Tennessee
Daryll
 

Going to start with some basic info needed: Baro reading? Either Hz or psi reading is fine What’s your elevation? Fuel pressure at idle and under load while accelerating? MAF @ idle and WOT under load and at what rpm? DPFE sensor reading at key on and idle? Manifold Vacuum in Hg? O2 sensor switching range? Hose from breather tube to valve cover connected? Lot of other things I want to ask but

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Adrean Diagnostician
Bakersfield, California
Adrean
 

If u have fuel trims high at all rpm ranges could be wrong Injectiors ,,

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Chris Technical Support Specialist
Commack, New York
Chris
 

If there is an issue with the injectors I would suspect the FuelPW PID (injector pulse width) should be excessive. Expect normal readings about 3.5 ms at idle for this truck and 5ms or so 25 mph cruise

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Arsalan Manager
Washington, District of Columbia
Arsalan
 

I have talk to customer about leaving the vehicle in my shop for proper diagnostic, I guess he needs to talk to his personal mechanic first since he was telling all this time to owner to change this and that. Will come back and update if he drop off the vehicle with me.

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Fred Owner/Technician
Santa Barbara, California
Fred
 

Not sure if you fixed this one, dd you check the purge valve, sometimes they stick open causing a lean condition, can you confirm its lean, using a gas analyzer, did you reset your KAM, Fords get stuck with old memory even after you repaired the vehicle

+1 Ð Bounty Awarded
Arsalan Manager
Washington, District of Columbia
Arsalan
 

Hello Fred. I have checked the purge valve and its holding pressure and working properly. I have told the customer to leave the vehicle in my shop for proper diagnostic.

0 Ð Bounty Awarded