Engine runs rough and codes PO175,PO172,PO351,PO161, and PO141

2003 FORD F-150
200,000 MILES • 4.6L • V8 • 2WD • AUTOMATIC
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SWEETIE1965
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Purchased this truck yesterday. The previous owner told me the engine was rebuilt about 6-8 months ago. Drove the truck home with it running rough. It has very little pick up power. It burned about $20.00 gas just to go about forty miles. When I got home, I scanned the truck with a handheld scanner. It gave me the following codes:PO175, PO172,PO351,PO161,AND PO141. According to the previous owner, someone told him the truck needs valve springs replacement. I'm really not sure where to start. I was going to try to do an entire tune up to see if that solves the problem, but I don't want to spend money for nothing. If you know what some or all of these codes have in common, would be greatly appreciated. And how do I go about repairing this truck? Thank you for your help in advance.
Oct 14, 2021 at 7:57 AM
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SQM
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Hello,

So, these are the codes:

P0141 - Oxygen sensor circuit malfunction
P0161 - Oxygen sensor circuit malfunction
P0172 - System Rich Bank 1
P0175 - System Rich Bank 2
P0351 - Ignition Coil circuit malfunction

Just about all of these are fuel / oxygen sensor related.
Possible causes are contaminated mass air flow sensor, faulty fuel pressure regulator, Leaking injectors, EVAP canister purge valve leak, vacuum leak, faulty oxygen sensor etc.

I think the best course of action would be to do a thorough inspection under hood for any fuel and vacuum leaks. Check all the vacuum lines as well as fuel lines. Inspect the fuel pressure regulator.
Do a thorough cleaning off the mass air flow sensor and the throttle body. Check the plugs for fouling. Replace if necessary.

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

After that you should clear the codes and run the truck and see what all code still exists.
This way you will be able to narrow down the possible issue.

I have attached more details on those codes below.

Let me know of any questions.
Thank you.
Oct 14, 2021 at 8:28 AM
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SWEETIE1965
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The motor oil in the truck smells like gas. Do you think it would be best to change the oil and filter? I have Motorcraft spark plugs and a fuel pressure regulator to replace them.
Oct 14, 2021 at 10:08 AM
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SQM
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Yes, it would definitely be a good idea to change the oil. Typically, you will get fuel in oil when the engine has been running rich for an extended period of time.
Oct 14, 2021 at 10:19 AM
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SWEETIE1965
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Okay. I will change oil and filter before starting the engine, so I don't cause further damage to the engine.
Oct 14, 2021 at 10:57 AM
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SQM
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Sounds good. Let me know how it turns out. Or if you have any questions.
Oct 14, 2021 at 11:08 AM
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SWEETIE1965
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Checked four spark plugs and coil packs, they seem to be in good condition. The plugs didn't have a gas smell to them. The coil packs had resistance of 1-1.5 ohms. Changed the fuel pressure regulator, it made a good difference in the way the truck runs. Would gas smell in the motor oil cause blue smoke to come from the tailpipe? All the codes are gone except the oxygen sensor codes. The previous owner told me all the sensors were changed when the engine was rebuilt about 6-8 months ago. Would gas fumes in motor oil cause blue smoke from tailpipe and slow pick up?
Oct 14, 2021 at 1:26 PM
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SQM
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Typically, the engine will produce blue smoke if it is burning oil (example: due to a leaky piston ring etc).

https://www.2carpros.com/articles/blue-smoke-from-engines-exhaust

Excessive smoke can make the oxygen sensor to not function properly or malfunction and go bad.
Follow this guide to test the sensor:

https://www.2carpros.com/articles/how-to-test-an-oxygen-sensor-02-sensor


Oct 14, 2021 at 2:00 PM
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SWEETIE1965
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Would a faulty oxygen sensor cause a hard to start condition? The truck runs better since I replaced the fuel pressure regulator, but it's still hard to start and the "get up and go" isn't there. It gradually picks up speed. Once the truck is going, I can smash the gas pedal and most times it will go. Sometimes not though.
Oct 14, 2021 at 2:37 PM
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SQM
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Oxygen sensor does not impact the start up. It could make it run rough afterwards.
Typically, hard start is due to either a fuel or spark issue.
Does it idle rough?
Oct 14, 2021 at 3:06 PM
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SWEETIE1965
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It idles fine. It just has slow pick up. Once it gets going its fine. Like about 40 MPH it's fine. Before that it's like slow pick up.
Oct 14, 2021 at 3:18 PM
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SQM
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So, it drives normal past 40 MPH? Normal acceleration?
Is there any noise associated with the slow acceleration?

Any other codes? See if you can scan for historical codes.
Oct 14, 2021 at 3:21 PM
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SWEETIE1965
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No. It has slow pick up until I get to about 40 MPH. After 40 MPH it gets a little bit better. And so on until I reach the speed limit. When I was driving it home last night, I noticed it backfired slightly only one time at about 30 MPH It hasn't done it since then.
Oct 14, 2021 at 4:10 PM
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SWEETIE1965
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No noise is associated with the acceleration. No excessive fuel pump noise or anything like that.
Oct 14, 2021 at 4:10 PM
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SQM
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I wonder if the catalytic converter is clogged. A clogged converter will have this type of slow acceleration as it will have too much back pressure.

Just so we have a clear picture. What have you replaced or serviced so far? and what is the code that you currently have?
Oct 14, 2021 at 6:38 PM
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SWEETIE1965
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I have checked 4 spark plugs which appears to be in good condition with a very faint gas odor, I have changed the fuel pressure regulator, which helped a lot. I have checked 4 of the coil packs, each one has a resistance of 1-1.5ohms, which according to Google is within specs, I have checked the mass air flow sensor and cleaned it out. It's hard to start any light blue smoke is coming from the tailpipe. The codes I get are oxygen sensor codes only. I was going to pull them off and try to clean them up before I replace them. I may be able to get away with cleaning them. The codes are: PO161 and PO141. That's the only codes. What is causing the hard to start condition after the previous owner told me the engine was recently rebuilt? But he may have lied. I can tell you; all the gaskets appear to be new. No leaks anywhere and engine is super clean. I did check the engine oil. It smells like gas, and it did go down some since I drove it home which is about 30-35 miles.
Oct 15, 2021 at 5:16 AM
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SWEETIE1965
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I forgot to mention, I also unplugged the PCV valve while the engine was running. There is no blow-by coming from the PCV. There is strong vacuum from PCV hose like normal.
Oct 15, 2021 at 6:18 AM
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SQM
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It is good possibility that the issue lies within the oxygen sensor or the circuit.
Inspect the harness for the oxygen sensors. Make sure there is no corrosion, short or broken/damaged wires. This can also be triggered by a damaged oxygen sensor. If the sensor is not getting adequate power due to wiring issue.
Oct 16, 2021 at 9:11 AM
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SWEETIE1965
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I checked everything I can think of. The only thing I haven't checked is the fuel pressure. I can check that to see if it has proper pressure and check for leaks at the same time. I will also check the fuel pump driver module. Everything I checked so far check out. I replaced the oxygen sensor. It was full of black soot so I'm sure it wasn't functioning properly.
Oct 18, 2021 at 7:02 AM
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SQM
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Here are the fuel pressure specifications:
Engine Running: 193-310 kPa (28-50 psi)
Key On Engine Off: 240-310 kPa (35-45 psi)

Let me know how it turns out.
Oct 18, 2021 at 11:24 AM
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SWEETIE1965
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I wasn't getting any fuel pressure at all but yet the engine would start and run. That's a new one to me. I think maybe the Schrader valve is bad or something. Well anyway, I found the fuel pump relay was not in the proper place, so I put it in its proper place. It started up easy the first time. Ever since then it's back to the same thing. Hard to start. It still idles rough but not quite as bad. I know there is gas in the oil or at least gas fumes in the engine oil. I have some brand new oil I will change it tomorrow. Now I'm leaning towards the fuel pump is weak.
Oct 18, 2021 at 3:00 PM
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SQM
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What was the fuel pressure?
Oct 18, 2021 at 6:52 PM
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SWEETIE1965
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The fuel pressure gauge was not reading anything at the fuel rail. I had all the proper fittings connected and all that. It wasn't picking up anything. So, I guess the Schrader valve on the rail is either worn out or just stuck. The fuel pressure gauge was brand new. I rented it from a local parts store. So, to answer your question, I have no idea what the fuel pressure was.
Oct 18, 2021 at 7:14 PM
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SQM
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Got it.
Knowing the pressure sure would have helped you.
You should be able to get a new shredder valve from the parts store. This way you are not just replacing the fuel pump without being sure. Also, if you have not yet changed the fuel filter.
Also, a clogged fuel filter can reduce the fuel pressure. Has that been replaced?
Oct 18, 2021 at 7:20 PM
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SWEETIE1965
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I will check the fuel filter tomorrow. I will also get a new Schrader valve tomorrow then recheck the fuel pressure.
Oct 18, 2021 at 7:24 PM
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SQM
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Let me know how it turns out.
Oct 18, 2021 at 7:32 PM
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SWEETIE1965
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I sure will.
Oct 18, 2021 at 7:43 PM
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SQM
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Great.
Oct 18, 2021 at 8:20 PM
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SWEETIE1965
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I found the problem. There are three faulty fuel injectors. I have a set ordered. I'll let you know how it does after I change fuel injectors.
Oct 23, 2021 at 8:26 AM
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SQM
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Glad you found the problem. Were those injectors not spraying properly? clogged?
Oct 23, 2021 at 8:29 PM
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SWEETIE1965
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The injectors were mechanically stuck open. Constantly spraying gas.
Oct 24, 2021 at 9:22 AM
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SQM
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Got it. That's why the rich running.
Oct 24, 2021 at 5:18 PM
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SWEETIE1965
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Sure is. I have a set of 8 ordered. They're supposed to be here Tuesday. If the weather permits, I will change them Tuesday if it's not too late. If it is then I'll just do it the next day. Thanks for all your help and advice on this subject.
Oct 24, 2021 at 7:50 PM
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SQM
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You are welcome.
Oct 24, 2021 at 7:54 PM
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SWEETIE1965
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Good morning. I received the new fuel injectors. Then I had to have emergency surgery or lose my foot. Well. While I was in the hospital, my stepson said he knows someone who can change the injectors. I said okay that's great. Well, when I got home from the hospital yesterday, I popped the hood on the truck to check things out. I was very seriously shocked to say the least. Almost the entire driver side of the engine was burnt!! Now this guy isn't answering my stepson's calls or anything. My question is, what would be a good, educated guess of repairs needed now? I know these for sure: coil packs, fuel injectors, hoses, EVAP solenoid, mass air flow. When I am able, I will take a few pictures to send you so you can see the damage done. And can I force him to pay for the repairs.
Oct 29, 2021 at 5:30 AM
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SQM
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Wow, that is crazy with the truck. I wonder what he did.
I hope you are doing well though.

As for the burnt parts, can you upload a video of what you can see is burnt?
Oct 29, 2021 at 6:41 AM
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SWEETIE1965
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Here's a video.
Oct 29, 2021 at 7:10 AM
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SQM
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That is quite something with all the damages. I think it will be the best option, as you mentioned in the video, is to go to a junk yard and take off all those components from a truck. All the harnesses and lines and any other burnt components.
From the video it looks like all those plastic components got burnt.
Did he install the injectors on this side?
Oct 29, 2021 at 10:24 AM
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SWEETIE1965
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Yes. They were installed on both sides.
Oct 29, 2021 at 11:17 AM
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SWEETIE1965
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I would need to remove all damaged components. Would I remove the main power cable from the PCM to the battery?
Oct 29, 2021 at 11:23 AM
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SQM
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If the main cable is burnt/melted, then yes.
From the video it looks like good amount of work. I think the best approach would be to first get those replacement components then start the remove them from your truck one at a time. This can help with keeping track of all the locations for those parts, especially the wiring harness.
Can you tell if it melted back of the injectors?
Oct 29, 2021 at 11:28 AM