P0171, P0174 codes

[BlindViper]

My 2011 explorer has/had p0171,p0174. So this morning I go out to look for the vacuum leak. Little brake cleaner all over the engine and nothing. I opened the the air box and the engine stumbled and picked up RPM. Checked the filter and it was dirty. So I run to the parts store, get a new air filter, carb cleaner, MAF cleaner. In the parking lot I changed the filter and headed home. 4 miles down the road coming to a stop sign the engine stumbled then picked back up. Then the gas pedal did nothing. So I put the trans it M to keep the RPM up. Then a few more miles it completely died leaving a stop sign. It would start then die, did this 20 times. Then I thought all I did was change the filter. So I opened the air box and left open it started. Got home turned it off then put the air box cover on and it started with out issue.

So I cleaned the MAF, throttle body, then sprayed all the vacuum/air box/intake connections with carb cleaner. Cleared the codes(P0174 P0171)and took it for a test drive. Its running fine I'll see if gge P0171,P0174 comes back.

What really concerns me is that the car completely died with no codes. Anyone have any thoughts?

 

[ProjectSHO89]

Check the inlet to the air filter box. You might have some trash that is blocking it.

 

[94Eddie]

These videos explain how to diagnose lean codes using fuel trim information.

 

[ProjectSHO89]

The linked videos do not apply to this newer generation of engine management system (which uses UEGO sensors), they're for the older HEGO-based fuel control systems.

 

[muddyexplorer]

I have a lean condition that has me stumped. As the title says I have 2014 Explorer Sport, no modifications that has been setting a P0171 with a pending P0174.
Ignore all the other codes....they were set while I was doing testing.

Only drivability issue that I have is low gas milage, about 15mpg. I've noticed that the LTFT rises the more idling it does and if it is being driven it will come down to around 15%. That would make be believe that it is a vacuum leak but I have smoked checked the system and found no leaks, and also pulled individual vacuum lines off the intake and capped the ports with no changes in the fuel trims.


I've gone through Ford's PC/ED troubleshooting steps with Forescan and have not gotten any failed results. The only thing that I haven't checked are the O2 sensors but I would think they would be ruled out since I am having issues on both banks. I have cleaned both MAP sensors and cleaned and tightened the intake hoses as I am getting oil into the intake from the PVC system.

I think I might pull the throttle body off next and check to make sure the throttle plate is clean and not letting air through when it is closed. Anybody have any other suggestions.

Below are the results of the Mode 6 test from Forscan since you can't run a cylinder contribution test with forscan.

 

[Turdle]

Can you apply smoke with pressure to the throttle body? Check for leaks at tps area and throttle plate shaft bearing bushings which would explain more unmetered air at idle

 

[muddyexplorer]

Can you apply smoke with pressure to the throttle body? Check for leaks at tps area and throttle plate shaft bearing bushings which would explain more unmetered air at idle

My homemade smoke machine does use an air compressor to push the smoke in, but it is regulated pretty low, only a few PSI

Also forgot to mention I sprayed down the the intake manifold and the throttle body and never heard a change in the engine nor saw any change in STFT's

 

[2016 ExplorerSportCA]

My homemade smoke machine does use an air compressor to push the smoke in, but it is regulated pretty low, only a few PSI

Also forgot to mention I sprayed down the the intake manifold and the throttle body and never heard a change in the engine nor saw any change in STFT's

I have had the same issue with my 16 Explorer Sport having a P0174 with LTFT being high in both banks. Last year I had a crack/hole in the air intake tube that runs to the front turbo. A year later I am here with the P0174 code again. It took me some time to find a leak and was able to find a leak coming from the throttle body mainly from the electrical components in the throttle body. My Explorer Sports starts up but has poor MGPs and rough idle after letting off the gas. So I am waiting for the part to arrive and once I have installed I am hoping that resolves the issue. Also, I also sprayed the throttle body to see if there were any change in the engine but there were no noticeable change.

So check the Throttle Body for leaks.

I should be getting the part this upcoming Monday, 01/29 so I will post my results.

 

[ProjectSHO89]

Also forgot to mention I sprayed down the the intake manifold and the throttle body and never heard a change in the engine nor saw any change in STFT's

Yeah, that usually doesn't work as the computer is too fast in making adjustments.

Instead, monitor your short term fuel trims while you spray. If you hit a leak, you'll notice an immediate spike in the ST trim(s) that then tapers back to the previous value in a few seconds.

 

[muddyexplorer]

Yeah, that usually doesn't work as the computer is too fast in making adjustments.

Instead, monitor your short term fuel trims while you spray. If you hit a leak, you'll notice an immediate spike in the ST trim(s) that then tapers back to the previous value in a few seconds.

I was graphing and watching the STFT's while I was spraying and nothing changed between spraying and not spraying.

 

[Atlas Antipode]

Do LTFT decrease under load (with sustained higher RPM)? Might be intake gasket. Could verify by spraying water around intake gasket and listening for engine hesitation.

 

[muddyexplorer]

Do LTFT decrease under load (with sustained higher RPM)? Might be intake gasket. Could verify by spraying water around intake gasket and listening for engine hesitation.

It does seem to decrease over time while it is being driven, and goes up while it is idling. While it is idling it will slowing climb to 29% and after a day or 2 of driving it will come back down to about 15-20%.
I did the H6 test posted below to check for changes in the fuel trims.

During the test the combined fuel trims at idle were 32% and 31% and they both dropped to 23% at 3500rpm. So that was a drop of about 9%. 15% of the total value at idle would be 4.65%.....so my answer would be NO, 9%>4.65%. I went on to H8 which is locating a vacuume leak, which is basicly capping the vacuume ports while watching the STFT's. I got no change in the STFT's, so the next step was check for vacuume leaks in the intake system and manifold. there was no procedure listed for that. That's when I sprayed all the intake parts with brake cleaner with no changes. When it quits raining here I am going to get under the car and check the tubing and connections at the turbo's

 

[muddyexplorer]

So I pulled off the intake tube to the front turbo because I was getting some smoke from the turbo area when I did my smoke test, and found the the molded plastic "clamp" the joins the rubber boot that clamps to the turbo intake to the plastic tube cracked.

I'm not confident that a leak between the air box and the turbo would cause a big issue since the air is not metered until past the turbos but I am going to clamp it temporarily while I wait for the replacement to come in, and monitor it to see if it changes anything.

 

[Turdle]

You used brake cleaner? Oooops

Try unlit propane hand torch, direct raw fuel right to suspect area.

Brake cleaner will damage chit

 

[2016 ExplorerSportCA]

So I pulled off the intake tube to the front turbo because I was getting some smoke from the turbo area when I did my smoke test, and found the the molded plastic "clamp" the joins the rubber boot that clamps to the turbo intake to the plastic tube cracked. View attachment 449377

I'm not confident that a leak between the air box and the turbo would cause a big issue since the air is not metered until past the turbos but I am going to clamp it temporarily while I wait for the replacement to come in, and monitor it to see if it changes anything.

I had the same issue with my Explorer Sport last year in March. Once it was replaced it had no issues with the P0174 lean code. This time that the P0174 lean code came back I was able to pinpoint the throttle body after putting smoke the electrical components weren't sealing. The new throttle body and gasket to arrive tonight so I can replace it tomorrow.

 

[muddyexplorer]

I had the same issue with my Explorer Sport last year in March. Once it was replaced it had no issues with the P0174 lean code. This time that the P0174 lean code came back I was able to pinpoint the throttle body after putting smoke the electrical components weren't sealing. The new throttle body and gasket to arrive tonight so I can replace it tomorrow.

I was able to use a hose clamp and and reclamp it for testing and there was no change in any readings, so I threw in the towel and took it to the dealer. They said there was a crack in the intake tube to the rear turbo so that is geting replaced. Hopefully that solves it.

 

[peterk9]

I had the same issue with my Explorer Sport last year in March. Once it was replaced it had no issues with the P0174 lean code. This time that the P0174 lean code came back I was able to pinpoint the throttle body after putting smoke the electrical components weren't sealing. The new throttle body and gasket to arrive tonight so I can replace it tomorrow.

The throttle body was an issue on the 2016 Explorer. There is a thread on it.

Peter

 

[2016 ExplorerSportCA]

The throttle body was an issue on the 2016 Explorer. There is a thread on it.

Peter

I was able to work on replacing the throttle body and gasket last night, but was unable to remove the hose that connects before the throttle body assembly and the intercooler pipe where the MAP sensor for the turbo boost pressure sensor connects. I sprayed some lubricant and let it sit overnight in hopes of being able to take off the hose to put on the new throttle body later today. Otherwise I would need to buy the Intercooler pipe Part #db5z-6f073-b as it is sold as one piece.

 

[peterk9]

Good luck, but in case you have to purchase the part; Original 2013-2019 Ford Inter-Cooler Pipe DB5Z-6F073-B | Levittown Ford Parts
Levittown is a forum vendor and offers members a discount.

Coupon Codes for Forum Members

Hi Guys, We have codes available for forum members so if your looking for Genuine Ford replacement parts or Accessories please let us know, Feel free to reply to this thread here and we will message you. Thanks! -Benny

www.explorerforum.com

Peter

 

[2016 ExplorerSportCA]

Good luck, but in case you have to purchase the part; Original 2013-2019 Ford Inter-Cooler Pipe DB5Z-6F073-B | Levittown Ford Parts
Levittown is a forum vendor and offers members a discount.

Coupon Codes for Forum Members

Hi Guys, We have codes available for forum members so if your looking for Genuine Ford replacement parts or Accessories please let us know, Feel free to reply to this thread here and we will message you. Thanks! -Benny

www.explorerforum.com

Peter

Well, I was able to get the hose and install the new throttle body, and run the re-learning procedures. However, I still have high LTFT.

I have noticed before and after the throttle body replacement that during a cold start once the idle drops from 1k rpm to 5k rpm the idle will surge like it is struggling to stay on for a brief second but then returns to normal idle. Given that the LTFT go down when accelerating I probably still have a vacuum leak. I will have to look at all the air intake hoses.

Things I have done:

1. MAP Sensor on top of the Intake Manifold - Replaced
2. MAP Sensor next to the intercooler outlet pipe - Replaced
3. Throttle Body - Replaced

Air Intake tube that connect to the front and rear turbo - Replaced last year in March- 2023 due to having a hole on them. Spark Plugs and one coil pack were replaced in April of 2022.


Mechanic that replaced the tube to the turbos told me that it could not be a vacuum leak and instead advised to have all spark plugs and coil packs replaced. I bought a smoke machine and checked for leaks but could not find one, but I am sure I probably missed it. I probably need to get under the truck and see if I seen anything.

So back to square 1.

I will check it out this weekend.

Any advise will be greatly appreciated.

Thanks!!!