system lean in bank 1 - p0171

Hello,

In the diagrams down below I have included the factory diagnostic troubleshooting guide for Direct Trouble Code (DTC) P0171. I see no listing for DTC P1133 listed for your vehicle. If you double check the DTC number for me I will be happy to look it up for you. The guide for DTC P0171 is pretty straight forward. I would definitely check for vacuum leaks. By vacuum leaks, what I mean is any unmetered, or any air leaking into the intake air system after the Mass Air Flow sensor (MAF). A good way to do this is to get a propane torch and crack it open on the lowest setting, making sure not to light it. You just want the propane coming out of it. With the engine running, run the propane torch along the air intake duct, throttle body, intake manifold, vacuum hoses, EVAP hoses, paying special attention to Positive Crankcase Ventilation hoses, EGR inlet, and the intake manifold, both inside the valley and outside. Anywhere there is a leak when the torch passes by it the engine rpm's will pick up as the propane will get sucked into the system. This will take care of this DTC. I have also included a link below for you to go to:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Please get back to us with what you are able to find out.

Thanks,
Alex
2CarPros

Okay, I sure will and thank you for taking the time to write me back. I will have to have another repair shop look into everything you said as to I can't get to them myself etc. Oh, I do have one my question. When someone says the 02 sensor is a upstream sensor what does that mean? And is the number one firing cylinder on the drivers side or the drivers side of the van? Just asking and I will get back with you what I find asap. Love this site!

Hello Warren! I have worked at a Ford dealer for over 27 years and can tell you with confidence that the intake gaskets will need to be replaced. We usually replace the top portion because the baffles come apart inside and rattle, (it has a two piece upper intake) and replace the gaskets on the lower portion. This is the main culprit for a p0171, p0174 codes.

Okay, i will have to see if i can find someone to fix this without costing too much. :-( What i don't understand is why did the check engine light stay off for a week and then come back on again? All i did was (with the van off) I disconnected the MAF and sprayed it very good with some CRC MAF cleaner and then put it back together and cleared the codes.. and it stayed off for almost two weeks and then comes back on. But thank you for taking the time to answer my questions.. You just don't know how much i enjoy this site.

That is the nature of the beast with vacuum leaks, especially with rubber seals or hoses, the leak is never the same day to day. Keep us posted after those gaskets are replaced! This is a must if they have never been replaced! I’m glad you enjoy the site! Cheers

Update: Well i just took it to my repair shop and i ask him how much would it cost to replace a intake the gaskets and he said "It would only cost me $450.00 to fix it ($450.00 is the cheapest place i could find to fix it too) and then he asked me is the van running good and i said so far it is. Then he said well as long as it is running good replacing the gaskets would be to much work just to take it apart and the service engine soon like still may not go off. So what should i do now? I thought he would jump at the chance to fix it for $450.00. But he said what i just told you.

Hello again,

If your vehicle is running fine, then I wouldn't mess with it. The DTC will keep your MIL or "check engine" light illuminated until it is erased from the PCM. There are to ways to do this. The first is to take your negative battery off the battery for 5 minutes or longer. This will completely erase your PCM's entire Keep Alive Memory, including all learned values and your vehicle will be starting from scratch. The second and the more highly recommended method, is to hook up a code reader to the Data Link Connector (DLC) and erase the DTC that way. Either way please keep us informed as to your vehicle's progress.

Thanks,
Alex
2CarPros

Okay i will try that. I have a quick question though. Yesterday i came home and something caught my eye and i saw this dark line in my passenger side back fender well. Come to find out i have a wheel cylinder leak. Would this cause a service engine soon light to come on? here is a video of it. i tried to record it the best i could.

Hello again,

It might cause the MIL to illuminate with an ABS DTC. The only way to know for sure is to get a code reader and pull the code(s). This will also allow you to erase the DTC(s) when the problem(s) are fixed. Here is a link below with how to pull the DTC(s) if you are unfamiliar with how to do this.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please go through this guide, if necessary, and get back to us with what you are able to find out.

Thanks,
Alex
2CarPros

A wheel cylinder leak will not cause a mil light to turn on, specifically an ABS light. And clearing the code will be like brushing dirt under a rug. As the vehicle is running lean the PCM is adding fuel to compensate so your fuel economy will suffer for sure! The vehicle may run “fine”, but over time this is not good for the engine. I used to get a lot of these at my dealership because most techs don’t want to do the work. I would shop around at other shops, specifically Ford specialty shops. Not trying to step on any toes, just my opinion.

Oh, oh okay. i was hoping that it might but i didn't think so. Looks like i may have to find a new repair shop too. Because i have been to the same one and this problem keeps popping up. Not the wheel cylinder leak but the error codes. And i will borrow my brother's scan tool or go to AutoZone etc., and see what the error codes says. Because i erased the codes before in 2018 but they would just back again. And thank you for the scan too guide i will try that too. And thanks guys for writing me. Because there's not a good trust worthy shop in my town that is close by where i live at all. Anyway, so much for my complaining i will keep you guys updated.

BMDOUBLE is one of our best! Please let us know what you find. We are interested to see what it is.

Okay, i will let you guys know for sure. (last code scan the codes where p0171 and p0174). The p1133 doesn't even appear anymore now. Tomorrow i will get the wheel cylinder leak fixed first ($24100 plus tax) I will have to save up for the intake manifold gaskets to get repaired etc. Anyway i will keep you guys posted for sure. Oh yeah, i almost forgot to tell you guys. I tried the squirting water test around the hoses, and from what i could around the intake manifold to see if the vans idle would change any. But there where no changes at all. Anyway that is the latest.

Please let us know what happens.

Update: Its not about the intake manifold gaskets but it is about the wheel cylinder leak. Or so i thought it was. Turns out my axle grease is leaking out and i need a new seal. So i just wanted to post this just in case someone sees the same black oil line inside their fender well and may not know what it is. Mine turned out to be axle grease etc

Good deal! Thanks for the update Warren!

Update: Getting closer to finding out what the problem is (intake manifold gasket). Someone i know is going to loan me a smoke machine and i need to know where to connect it so i can see if the smoke will come out of the intake manifold. I connect it to the brake booster vacuum lines correct? I haven't ever use a smoke machine before so.

Correct, connect it to the main vacuum feed to the intake manifold which goes to the brake booster. let us know what happens.

Okay and thank you so much for taking the time to answer. I didn't mean to post the same thing again.. I was trying to delete my other post but i didn't see how etc. And I sure will let you know. :-)

Please let us know what you find. We are interested to see what it is.

Just to let SCWICKEDSTANG know, someone saw the trouble i was having and bought me a new maf sensor and had it installed and they erased the error codes on my van. I think they think that is going to fix it but i have been replacing maf sensors on my van since 2018 and the error keeps coming back. the same ones P0171 and P0174. And by the way i have been driving my van and so far it hasn't been any new codes set as of yet and it still runs good so far. Also, A new maf sensor was installed not to long ago too and it didn't turn the service engine soon light back off either. It still shines so pretty and annoying too.. lol But i will let you know as soon as I can. Looks like i will have to find a shop that has a smoke machine etc..

The P0171 is because the system is too lean. it could be a fuel injector is becoming weak. I would remove all spark plugs and check the color to see if one is a little different this will be the cylinder that needs to injector. Here are two guides to help:

https://www.2carpros.com/articles/how-to-change-spark-plugs

and

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

Please run down these guides and report back.

Sorry to say Warren but the lean codes will not go away until that intake is replaced! The bolts that hold down the plastic intake to the lower aluminum intake have grommets on them that harden and fail over time and are non replaceable, they only come with the plastic intake. Monitor the upstream oxygen sensors HO2s11,HO2s21 and spray the intake with brake clean or carburetor cleaner where the plastic intake mates to the aluminum intake. If the volts spike up to 1 volt and stay there for several seconds, bingo vacuum leak identified. This is how I do it because it’s quick and effective.

Nice work on the vacuum leak detection method, is it okay to add this info to the site vacuum leak guide?

Thanks Ken! Absolutely!

Sweet!

Hey Ken and BMDouble thanks for the information. I will see if someone will do this for me. What both of you said to try etc But if the intake has to be replaced it will have to wait. I can't afford to have that done now. sad to say etc Also, I got tired of waiting on people to help out with the smoke machine so i tried what SCWICKEDSTANG said and clear the codes but before i did clear the codes i put in another mass air flow sensor in there. A new one that is. Well the box to the thing said it was new anyway etc. But i notice something on the old mass air flow sensor i pulled out of there. Someone wrote the word "good" or what ever it is they wrote on the bottom of it. Like they kind of engraved it sort of. And it had a red mark of some kind like they had marked it for some reason. Like a red dot on it. Now that may not mean anything but that's the condition the old mass air flow sensor was in when took it off etc. Well anyway, the check engine light is off for the moment now. I will post the picture of the mass air flow sensor up.. as soon as possible so you can see it for yourself etc.

Here's what it looked like the mass air flow sensor we took off ourselves. Plus it was a remanufactured one too. I had a brand new one on there before the repair shop replaced it with this one.

Hello again,

Usually, junk yards or pick n pull places will put red dots on parts that they recycle that are in good working order, so that's nothing to worry about. What you need to worry about on MAF's is the two fine platinum wires. You can purchase MAF cleaner at any auto part store specifically formulated for cleaning these wires. It is manufactured by CRC and dries very quickly so as not to damage these wires. The way a MAF sensor works is these two platinum wires heat up to 500 or so degrees. As the air flows past these wires as it is entering your engine, the wires cool down and more electricity is needed to be added to heat them back up to 500 degrees. The PCM is able to read this electricity and correlates it into the amount of air entering the engine. If there is corrosion, or a bug, or something on the wires, then more electricity is going to added, and the information that the PCM gets will be skewed. Anyway, please keep us informed as to your progress.

Thanks,
Alex
2CarPros

Oh, oh okay. I didn't know that. about how the junk yards operate. Thank you for the information Alex on how the mass air flow sensor works too. I have a can of CRC mass air flow cleaner. I had sprayed it on the sensor i posted up there at one time but the error code came back. I drove it today and it ran really good and the service engine soon light is still off where i cleared the codes. (I believe the Lord fixed it for me myself. People laugh at me when i say that. But I believe he did.) The funny thing is i am so used to it being on. It looks funny it being off, lol. Not that i am complaining it being off etc. Well anyway, if anything else comes up i will keep you guys posted. I just wished i had a scan tool that does live data so i could read the computer while it is running good and not producing any error codes.

Hello,

Good for you. We love to get posts that say the vehicle is fixed. The Good Lord or not, good job,

Thanks,
Alex
2CarPros

lean burn code PO174.

it may be an O2 sensor, but check fuel pressure first. you can get this code with low fuel pressure as well as a vacuum leak. so check hoses for cracks/broken etc. Auto parts rent gauge, see link.
https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Thanks again guys (SCWICKEDSTANG, Ken, BMDOUBLE) for all of your help!!!

Anytime Warren!

Thank you DMDOUBLE. Also, i posted something about my van door on here but i don't see what happened to it.. I have that fixed now.. I tried to delete the comment but it won't let me get to it..