Loses power, suggested it might be a fuel pump or vacuum leak

Hi,

The idea that both bank 1 and 2 are being affected could be an issue with a lean fuel mixture. As he told you, that it can be the result of a vacuum leak or low fuel pressure.

By any chance, do you have the codes that were removed? If so, let me know what they are.

Next, a power loss as you described can also be related to a plugged catalytic converter. Take a look through this link. It explains common symptoms related to this type of issue.

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

Let me know if what you experience mirrors the symptoms mentioned in the link above.

At this point, without the codes that were deleted, I'm not 100% sure which way to tell you to start. However, I would think looking for vacuum leaks and checking fuel pressure would be a good place to start. If you are comfortable doing it, here are two links explaining how to test:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

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

Let me know your thoughts on the converter. Also, let me know if you are comfortable performing the checks above. You will need a fuel pressure gauge, but most parts stores will lend one to you. If you look at the pic below, I provided the manufacturer's fuel pressure specifications.

Let me know. Also, please confirm if this is a 3.0L engine or a 3.4L.

Take care,

Joe

See picture below.

P0171, P0174, I forgot there was a 3rd one P0401(the device I used said it relates to the EGR, which I recently replaced. Thanks for the quick response.

Hi,

You are correct. It is related to the EGR. When you replaced it, did you inspect the intake where it mounts for carbon or any restrictions? Also, is there a vacuum to the EGR? The code is specific to the EGR being stuck closed. Also, is the code still present?

There is an EGR vacuum regulator that can be bad as well. If you look at the pic below, I attached a pic of it. Have you inspected that component for vacuum leaks or the connector for electrical issues?

Let me know.

Joe

See pic below.

I assumed if I replaced the valve and solenoid, my mechanic should have done that. The light is still on, and I called him waiting to see when he has time. If I had got a new fuel pump, filter and strainer, will this allow me to drive without fear the car will stop unexpectedly?

Hi,

If low fuel pressure is the cause, yes, it should be okay. But we don't know if that is the case. Since we have a lean fuel mixture and EGR codes, I have a feeling there is a leak causing the issues and not the fuel pump.

Not being there does make it a bit more difficult for me, but that is my theory at this point. Do me a favor. Locate the regulator and see if it appears new. Also, make sure the vacuum hoses to it are in good condition and not loose.

Have you checked fuel pressure?

Let me know.

Joe

I went ahead a replaced the fuel filter, I then rented a fuel pressure gauge kit. I believe it should be anywhere from 37-48 range yet, idling it didn't go pass 25 and revving the engine it didn't get pass 31. Is it possible the fuel pump needs to be replaced? The car cranks over, starts, but the engine dies immediately. Besides a smoke machine is there a less expensive way to check if there are vacuum leaks? Oh, by the way I still have the same codes.

Hi,

The specs indicate 30 to 32 psi at idle and up to 30MPH. I attached them below. The 25 is low, so it may be the fuel pump is just weak.

As far as checking for vacuum leaks, you can use carburetor cleaner. Here is a link that explains how it's done:

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

Let me know if that helps.

Joe

See pic below (pressure specifications).

Joe, you got a moment?

Hi,

I would be happy to call, but it's prohibited by the site. They want everything kept online.

Let me know what is happening and what I can do to help.

I hope you understand,

Joe

Okay, after all the advice you provided, I eventually purchased a new fuel pump. The psi was low, so I had a new one installed. When I picked my car up on Mar 26, 2022, I then drove it on Mar 28th, and it literally cut off. I stirred it to the side of the road and was able to start it again. Once I got home, I called my mechanic and he suggested I bring it in. I then waited and today I drove it again, this time it stopped on five different occasions, the code this time showed p0401, my mechanic said it was the EGR valve, so I had it towed to the place where the EGR valve was put in. They said at first, the EGR gasket was out of line, after that mechanic drove it for a few minutes, the same error occurred. Now I am waiting for them to determine if it's a bad valve or solenoid. What is your assessment? Thank you

Hi,

The code is specific to the EGR (insufficient airflow). It could be the EGR is stuck, there is no vacuum to it or the diaphragm in it is bad, the intake is carboned up causing a restriction, or an electrical issue.

What have they checked so far? Also, if the gasket were leaking, it wouldn't be a restriction.

Let me know.

Joe

According to the mechanic after diagnosing whether the EGR valve is good, he said the throttle position center is not sending a signal. The code is gone, and the rpms go to 250, when they rev it up, it acts like it wants to shut down, thus far hasn't. They suggest a full diagnostic on their ob2 systems, or just replace the throttle position or for me to walk away since they determined it wasn't the EGR valve or solenoid. Any ideas?

I called my mechanic at the dealership and explained what the other mechanic said where i had the EGR installed, he insisted the EGR valve is not good. So, i called where the EGR valve was installed, suggested they install a new one since it was less than 2 months ago installed, can you explain the difference between a scanned code and a full in-depth diagnostic check. Also, if there are two different opinions from two mechanics, how as a consumer am I supposed to distinguish which is the correct one? I also noticed that your replies have been well thought of, unlike the actual conversations i am having with these two mechanics, for that i am extremely grateful. All i want is my car fixed and unless it is determined what is causing it to shut off, I am afraid to drive it in fear of causing an accident should it shut off in the middle of major traffic.

Hi,

A scanned code is basically retrieved from the vehicle's computer and nothing more. In most cases, the code is used as a starting point.

An in-depth diagnostic check is where the component in question is physically inspected to determine the true cause of the code.

As a mechanic, I start with a scanner to retrieve a code. That is what I use to start checking. One must keep in mind; a code is a generalization. It doesn't indicate the cause of a problem.

Does that make sense?

Let me know.

Joe

Okay, do I replace the throttle position sensor or run the in-depth diagnostic or both? What about the different opinions from the two mechanics? You never replied about the sensor not sending the signal. Though the car starts it's not safe to drive because it dies at any given moment. What is your expert advice because I have no idea what to do?

Hi,

If it were a family member's vehicle, I would follow through with an in-depth diagnostic test. Simply replacing the EGR may not fix the issue.

Please let me know if you have other questions. It is much more difficult doing it online and I don't want to miss anything.

Take care and I'm here if you have questions or if there is anything I can do to help.

Joe

So, what about the first question when the two mechanics did not agree? If they put a new EGR valve and it gets the same error, where do I go from there? I am having trouble believing both of them. You never responded on how I should proceed. The P0401 indicates an EGR issue, yet if the new one ends up with the same problem, I am not sure what to do. Again, I don't want to nickel and dime if neither one of them can determine the problem. I need some major advice and any at this time will be appreciated.

Morning Joe, sorry to bother you again. When i towed the car in i was able to pick it up on Friday, drove it home, no problems. I drove it the next day, no problems, today i drove it about 4-5 miles and it stopped again. While the car was in the shop, i had them replace the EGR valve, this time one of the mechanics did something, so they claimed they gave me a new fuel regulator. In summary, i keep getting the P0401 error, i replaced the pump, filer, valve, solenoid and regulator, not sure what to do next. I will have them hook it up for an in-depth diagnostic. any suggestions?

There are several different things that can cause the P0401. However, the code indicates insufficient airflow. When they replaced the EGR, was the inside of the intake where it mounts checked for debris?

Let me know.

Joe

Since the mechanic who installed my pump said the EGR valve was bad, I had my current mechanic replace it, so I am assuming if it's brand new it's okay and they by no means will tell me whether the new one is dirty or whatever. In saying all this, what can I expect after replacing all these parts.

Hi,

What can be expected? That's hard to tell. By replacing the EGR, we assume the wiring is good, the vacuum supply to the EGR is good, the controls are actuating correctly, and there is a clear passage through the intake allowing air to freely flow.

Is the P0401 the only code that is returning? Also, when it stalls, does it start right back up? Also, when this happens, how would you best describe it? For example, does it feel like someone simply turned off the ignition switch, or does it slowly lose power as if it is running out of fuel?

Let me know. Also, you are not a bother whatsoever. Please remember that. I'm here to do my best to help. I saw that in the first post you sent today and forgot to tell you this.

Take care,

Joe

Yes, it starts right up. It feels as if the ignition is turned off, and yes thus far it's still the P0401 error code. I have been all over the internet trying to figure out what to do next. I am going to schedule an in-depth diagnostic cause I have no answers. Sorry I just feel both of these mechanics are not empathetic to my concerns. Also, instead of them driving it for a bit to ensure the codes are clear, they just say the car is ready for pickup. Since it's an older vehicle, selling it wouldn't do absolutely nothing. I do appreciate the time you invested in this, and I will keep you informed when the issue is fixed.

Hi,

You are very welcome. I just want to help you get it fixed. The odd thing is that it feels like the key is turned off. An EGR issue would usually cause it to slowly stall or just run poorly.

Regardless, let me know what you find or if there is anything I can do to help.

Take care of yourself.

Hey Joe, just keeping you updated. I bought my car on the 7th of April and asked for the in-depth diagnosis. Here it is the 21st and according to the service tech, they claim they did a combustion check, and it didn't look promising. My question is, when they run those diagnostics checks, shouldn't there be some sort of printout as to what was checked and what the results were? Also, shouldn't there be a schematic of what a in depth diagnostic consist of? I am extremely bothered because this auto shop has had my car for over 2 weeks and as far as I know, nothing has been done to determine the problem. I really need some advice as to know what to do next. The last time I was in, they put a new fuel regulator in, yet failed to drive it to see if the code shows up, so when i came and picked it up, and drove it home about 5 miles, it stopped and got the same code. They can't just clear the code without determining what the cause is, please any advice would be helpful

Hi,

I am sorry to hear this hasn't been resolved. If the P0401 is still present, we need to do is remove the EGR valve and check things ourselves. There are several things that can cause the code, but the code simply indicated an insufficient EGR flow problem.

Has anyone confirmed the intake where the EGR port is clean and free of debris? If not, that is where I would start. If it is clear, then we need to next test for an electrical issue that can also cause the issue. Take a look below and let me know if you are comfortable doing what is listed.

However, I would start by removing the EGR and inspecting the EGR port for restrictions. Follow the directions in pics 2 and 3 which are how to remove and replace the EGR. Once it is off, then check where it mounts on the intake manifold for evidence of carbon or anything that can restrict airflow.

Let me know what I can do to help.

Joe

See pics below.

Thanks, but can you answer some of the specific questions? They said the combustion test didn't look too promising, what could that possibly be? and will I be able to see the results of the diagnostic test? Not sure how to respond if they say it's something major without evidence. Please help me understand.

Hi,

A combustion test is meant to check the level of combustion gases in the engine coolant. If there are gases, there could be an issue related to a leaking head gasket.

As far as the diagnostic test is concerned, that is certainly for you to see. If they can't provide it, don't pay them.

Let me know how things turn out or if you have questions.

Take care,

Joe

Thanks Joe, just to keep you in the loop. I finally got the car back, they did a full diagnostic, cleaned throttle body and intake EGR passages, replaced IAC valve, also said he found a vacuum leak, parts were Fel-Pro fuel injection throttle body mounting gasket, Duralast idle air control valve. The owner drove it about twenty-five miles, various hills, roads, etc. No engine light came on. I picked it up, then a day later the engine light came back on. I called and explained so now it's a matter of time before he comes to look at it again. They didn't charge me anything. When i use the fixed, it shows codes p0174 and p0171. I sent him a text to see if the mass air flow sensor was cleaned or replaced. I really have no specifics as to what was the results of the full diagnostics. What next?

Hi,

Based on the codes you provided, it's getting too much fuel. If could be a few different things. However, I suspect it is fuel pressure related. Take a look below. I provided the info below related to both codes.

The first thing I recommend is to check fuel pressure. The fuel pressure regulator could be bad.

Let me know.

Joe

See pic below.

They replaced the fuel regulator, what about the mass airflow sensor. Remember, i have a new fuel pump, regulator, filter, EGR valve/solenoid, everything i recently described and now these codes, The purpose of me replacing the pump was originally because of those two codes. I mentioned earlier i rented a fuel pressure gauge and based on the numbers i determined the pump was bad. Now I am getting the 171 and 174 codes. Please any ideas, i am so frustrated because all the time the mechanic had the car they still can't seem to figure it out. Again, i wasn't charged, but how do i pinpoint exactly what the issue is?

Hi,

If the mass airflow sensor is faulty, it can cause either a lean or a rich fuel mixture based on how it's reading. Do me a favor, we can do this one of two ways. First, you can try cleaning the MAF to see if it takes care of the issue.

Here is a link that explains how it's done. Note that you should purchase a cleaner made specifically for the MAF.

https://www.2carpros.com/articles/mass-air-flow-service

Second, clear the codes and disconnect the sensor. That will force it into a predetermined setting and should indicate a code for the MAF and not the other issue.

If you have a live data scan tool, check to see if the ECT (engine coolant temperature sensor) is signaling an accurate temperature. Do this with the engine cold. It should be very close to the ambient temperature. If it is faulty and telling the PCM it's -40F, the ECM doesn't know it's wrong and makes the fuel mixture very rich to run in such cold temperatures. See pic 1 for location.

Also, we could check the voltages at the O2 sensors to see if they are off causing a rich mixture.

Is the P0401 still active?

Let me know.

Joe

See pic below.

I no longer have the P00401 code, just the 171 and 174. I talked with the mechanic and i told him to order a new MAF and a new 02 sensor, got an appt next Thursday. The things you mentioned I am limited to try, so i had a meeting with the owner and am willing to give them a chance. So far, I have no money out of my pocket. I will keep you in the loop and if you have any new revelations, don't hesitate to share. Thanks again.

Hi,

Thank you for the update. I look forward to knowing if that takes care of the problem.

I'll watch for your reply.

Take care,

Joe

Hi Joe, sorry it took so long getting back to you. Long story short, I took it somewhere else, they diagnosed the problem in about 10 minutes. Looks like there is a vacuum link on the manifold. It still is runnable yet overtime it may get worse. The guy told me that this part may be hard to find so i will see what happens next. Appreciate all your help and i will keep in touch should any other crazy problems arise. Thanks again

Hi,

Thank you for the update. I appreciate it. So what part are they telling you may be hard to find? The 3.0L v6 is an extremely common engine.

Regardless, take care of yourself, and please feel free to come back anytime. You are always welcome here.

Happy 4th of July!!!

Joe

It's the lower intake manifold.

Hi,

The lower intake manifold isn't difficult to find. The original part number for it is XF2Z9424EA. If you type in Ford part number XF2Z9424EA, it will bring up places selling it. The only issue is cost. They are expensive new. However, take some time and see if you can possibly find a used one from a salvage yard or even eBay.

Let me know if there's anything I can do to help.

Take care,

Joe

Hey Joe, been awhile. Just to keep you updated. The light hasn't come on since, except today. I Googled the part number and it said this: Intake Manifold - Ford (XF2Z9424EA)
MSRP: $516.18
Discount: $51.62 (10% off)
Sale Price: $464.56
This part does not fit your 2012 Ford E-350 Super Duty
Change vehicle
But it also said this below : Intake Manifold - Ford (4C3Z-9424-AA)
Shop for related parts in Engine Parts
MSRP: $276.67
Discount: $89.92 (32.50% off)
Sale Price: $186.75
This part fits your 2012 Ford E-350 Super Duty
Change vehicle

Do I need to confirm the VIN number to insure it fits?

Where are you getting that information? I don't feel either of the vehicles they indicated would have a 3.0L.

In 1996, they had a standard 3.0L, one that could run on flex fuel, and one that had a duel overhead cam which I believe was in the SHO. It was a high performance. The part number I gave you is for the standard one or the one that can use flex fuel. If you do have the DOHC engine, that would be different.

Just to confirm, I looked up a 2012 E350 super duty. See pic 3. It either had a V8 or a V10 engine.

Let me know.

Take care,

Joe

See pics below.

Joe, you sent me that number and I googled it like you suggested. This is for my 96 Ford Taurus.