P0171 and P0174 2006 F250 5.4L 3v

Since I don’t know how to diagnose, I decided to be a parts changer. I bought a new MAF, Fuel Pressure sensor, Runner control valve, and Fuel pump module. So now I have all of those parts. Which one do you think I should try first, what do you think is the most likely culperate? I would like to return the ones I don’t need. There was a Ford Tech who says the FRP Sensor can cause lean codes and drivability issues. He didn’t specify if that was an issue when the system is at desired fuel pressure. So again, missing info to be accurate.

I appreciate the info you have given. Thank you for that. However, some direction on what I should be looking at is what I need to know. I don’t have a vacuum leak, the MAF is new but questionable, the o2 sensors are all 4 new and honestly were probably never bad. Have lean issue and drivability problems. What could cause lean on both banks and drivability issues besides a MAF and low fuel pressure, as I have put those on the back burner. Fuel pressure is good, verified with manual gauge at 75 psi KOEO.

You keep saying to track down lean code problem but haven’t given me a possible cause of those. What all could cause my lean codes and drivability problem? MAF, FRP Sensor, Low Fuel pressure, what else?

How about bad injectors? I have a leaking fuel pump check valve so I am not sure if I can test the injectors as the pressure leaks down pretty fast at 5psi drop within one minute. Would there be a code if there was an injector problem, other than rich or lean codes?

This is info from Mitchell1 for diagnostics for P0171. There is no suggestion for both P0171 and P0174. So some of these may be bank specific causes????

Mitchell1: P0171
The adaptive fuel strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. Refer to powertrain control software, FUEL TRIM for more information.

Possible Causes:
Fuel System: Damaged or leaking fuel pulse damper (I have no idea what this part is or where it’s located or how to test it)
Fuel filter plugged or dirty (has new fuel filter)
Damaged or worn fuel pump (supposedly has new fuel pump but does have a out of range code and check valve bleeds down)
Leaking fuel pump check valve (definitely has this problem, but Danner said this can’t be the cause)
Leaking/contaminated fuel injectors (not sure how to test but very likely)
Low fuel pressure or running out of fuel (definitely does not have low fuel pressure, checked manually and on pid)
EVAP canister purge valve is leaking when the canister is clean (I checked this valve and it does close properly and doesn’t leak)
Fuel supply line restricted (I have no idea how to check this, could have good pressure and not getting enough flow? Wouldn’t run good at high rpm, I would think not anyways. Plus fuel pressure reads 40 psi on wot test)
Fuel rail pressure sensor bias (I have no idea what a sensor bias is, unless that’s sensor bias voltage?????, did have a code for fuel pressure sensor)

Air Induction System:
Air leaks after the mass air flow (MAF) sensor (not likely as I did a carb cleaner test and water test, no motor response)
Vacuum leaks (not likely, did water test and carb cleaner test)
PCV system is leaking or the valve is stuck open (no way to test as this part is build in to the valve cover and not accessible)
Improperly seated engine oil dipstick (checked this and no obvious leaks)
Air induction turbulence due to incorrect air filter (has correct air filter and its clean)
Again, no lean condition at idle after MAF replacement so not likely to be air system, according to Scanner Danner’s 28 years experience, Danner did say that a leak before the MAF sensor could cause drivability issues and lean codes. I inspected for this but did not smoke test. I would think it would have to be a pretty big leak prior to the MAF to cause problems, a pinhole leak would likely not effect the drivablility.

Exhaust System:
Exhaust leaks in the exhaust manifold gasket or mating gaskets before or near the HO2S (possible, but have no idea how to check, but do not hear any exhaust leaks in the manifold)

EGR System:
Vacuum hose disconnected on exhaust gas recirculation (EGR) system (not sure if I even have an EGR system????, but no hoses are disconnected anywhere)
module (ESM) applications (don’t know what this is or how to test it)
EGR valve tube/gasket leak (don’t know if this exists or where it’s located)
EVR solenoid vacuum leak (no idea what this is, but again, now have good reading at idle and no lean condition at idle)

Secondary Air Injection:
Damaged secondary air injection system or a mechanically stuck valve (No idea what or where this is or how to test it)

Air Measurement System:
Damaged or contaminated MAF sensor (I think this is still a possibility but MAF sensor is new)



Thanks,

I appreciate the info you have given. Thank you for that.

However, some direction on what I should be looking at is what I need to know. I don’t have a vacuum leak, the MAF is new but questionable, the o2 sensors are all 4 new and honestly were probably never bad. Have lean issue and drivability problems. What could cause lean on both banks and drivability issues besides a MAF and low fuel pressure, as I have put those on the back burner. Fuel pressure is good, verified with manual gauge at 75 psi KOEO.

You keep saying to track down lean code problem but haven’t given me a possible cause of those. What all could cause my lean codes and drivability problem? MAF, FRP Sensor, Low Fuel pressure, what else?

How about bad injectors? I have a leaking fuel pump check valve so I am not sure if I can test the injectors as the pressure leaks down pretty fast at 5psi drop within one minute. Would there be a code if there was an injector problem, other than rich or lean codes?

This is info from Mitchell1 for diagnostics for P0171. There is no suggestion for both P0171 and P0174. So some of these may be bank specific causes????

Mitchell1: P0171
The adaptive fuel strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. Refer to powertrain control software, FUEL TRIM for more information.

Possible Causes:
Fuel System: Damaged or leaking fuel pulse damper (I have no idea what this part is or where it’s located or how to test it)
Fuel filter plugged or dirty (has new fuel filter)
Damaged or worn fuel pump (supposedly has new fuel pump but does have a out of range code and check valve bleeds down)
Leaking fuel pump check valve (definitely has this problem, but Danner said this can’t be the cause)
Leaking/contaminated fuel injectors (not sure how to test but very likely)
Low fuel pressure or running out of fuel (definitely does not have low fuel pressure, checked manually and on pid)
EVAP canister purge valve is leaking when the canister is clean (I checked this valve and it does close properly and doesn’t leak)
Fuel supply line restricted (I have no idea how to check this, could have good pressure and not getting enough flow? Wouldn’t run good at high rpm, I would think not anyways. Plus fuel pressure reads 40 psi on wot test)
Fuel rail pressure sensor bias (I have no idea what a sensor bias is, unless that’s sensor bias voltage?????, did have a code for fuel pressure sensor)

Air Induction System:
Air leaks after the mass air flow (MAF) sensor (not likely as I did a carb cleaner test and water test, no motor response)
Vacuum leaks (not likely, did water test and carb cleaner test)
PCV system is leaking or the valve is stuck open (no way to test as this part is build in to the valve cover and not accessible)
Improperly seated engine oil dipstick (checked this and no obvious leaks)
Air induction turbulence due to incorrect air filter (has correct air filter and its clean)
Again, no lean condition at idle after MAF replacement so not likely to be air system, according to Scanner Danner’s 28 years experience

Exhaust System:
Exhaust leaks in the exhaust manifold gasket or mating gaskets before or near the HO2S (possible, but have no idea how to check, but do not hear any exhaust leaks in the manifold)

EGR System:
Vacuum hose disconnected on exhaust gas recirculation (EGR) system (not sure if I even have an EGR system????, but no hoses are disconnected anywhere)
module (ESM) applications (don’t know what this is or how to test it)
EGR valve tube/gasket leak (don’t know if this exists or where it’s located)
EVR solenoid vacuum leak (no idea what this is, but again, now have good reading at idle and no lean condition at idle)

Secondary Air Injection:
Damaged secondary air injection system or a mechanically stuck valve (No idea what or where this is or how to test it)

Air Measurement System:
Damaged or contaminated MAF sensor (I think this is still a possibility but MAF sensor is new)

I found a loose battery positive terminal and cleaned up a vehicle ground for the fuel pump driver module. Also noticed a wire hanging out of the fuel pump driver module connector, it was open and potentially could have shorted to a crack in the ground wire next to it. Fixed that and now I am waiting to see if i get anymore codes. The ignition key code was a B code, didn't see B codes in mitchell1 or on the Verus. Still have lean condition at any increase in throttle, idle is not lean but is rough. The temporary codes only show IMR valve stuck closed, but MIL hasn't come back on for the lean condition yet. Still waiting to finish drive cycles.

Thanks,

For the imrc the rods have two clips on each rod. One at the imrc motor and one at the intake. Usually it's the ones on the intake that break. Use a inspection mirror to see if the one end is broken. If it is you will need to remove intake and clean the butterfly's in the runners of the carbon buildup. This will take care of the imrc codes in question. The other possibility for the lean codes would be the egr assembly if it has a metal tube that runs from the egr into the intake. It's common that the egr flange to intake tube corrodes and deforms the calibrated gasket causing a vac leak. (May not be this way on your 5.4) but is worth mentioning.

I checked the rods and clips both visually and wiggled them manually to make sure they are connected. Checked the valve, it was not opening when the verus said it was opening. Need to check electrical but its pretty far in the back and havnt figured out how to check wiring when I cant reach the wires. If you have any suggestions, that would be cool.

I will check the egr valve hose and let you know.

I checked everywhere online and no one sells an EGR valve for my truck. Also couldn't find one online that anyone has replaced. If you could help me out and tell me how to locate this mysterious valve, that would be great. How about send a pic of my motor with the valve in the picture????? That would be really helpful.

Thanks,

I did inspect the IMRC valve for opening, it was not opening even though the verus said it was. After further inspection, I found that the connector was not connected. After playing stretch-arm-strong and twisting and turning and maneuvering my arm in directions I did not know it would bend, I got the connector plugged back in. It seems someone had disconnected it. It appears to be opening and closing now. Haven't verified yet, but from the sound of the motor on snap throttle, I think it's working.

Thank you for the direction which led to this discovery, I believe my (IMRC valve stuck closed) issue is solved. 1 down 4 to go...

I can not find the EGR valve. I found a hose that goes from the valve cover to the intake, which I think is my pcv valve hose, but no EGR valve. Mitchell shows one on the throttle body but it's a turbo diesel diagram. I can not find one on my truck. I researched online and they said it looks like the purge valve and is located near it, but no luck finding it. I have no idea where it is located.

Ok your engine must not have one then. So don't sweat looking for one.

Oh no, Im going to keep looking for it. Im sure it's there somewhere, otherwise you wouldn't have sent me looking for it.

I wouldn't waste your time the 06 f150 with 5.4 has a EGR valve not a f250 5.4 for whatever reason.

I have found that information to be accurate. The F150 has the 5.4L but it does have a different setup. I believe it has the air filter in a different spot and also seems to be many differences.

How can you possibly help me if you don't know what system I have?

Danner says that the only way to work on a car, is to learn your systems first. Diagnosis 101.

When you work on alot of different makes and models it is hard to remember accurately which has what system. It is another thing entirely when you work at a Ford dealer and work on only ford's or a few off brands. Hense why I said in my one response this may not be the case with your 5.4 liter.

RexPE1 wrote:

How can you possibly help me if you don't know what system I have?

Danner says that the only way to work on a car, is to learn your systems first. Diagnosis 101.

You might want to give Hardtopdr2 a break. He's going out of his way to help you through a complex diagnosis. I seriously doubt it was his intention to send you down the wrong path. He did also qualify his remarks about the EGR valve:

It's common that the egr flange to intake tube corrodes and deforms the calibrated gasket causing a vac leak. (May not be this way on your 5.4) but is worth mentioning.

Back to some of your questions:

Yes, the code is key in switch. I saved a pic but cant find it now. It does not say what triggered the code. The code is not even on there anymore. Lost it after I cleared the codes post MAF. Can't remember if it came back or not. Why? What does key in switch code mean?

There's a physical switch attached to the top of the lock cylinder housing that detects if a key is physically in the lock cylinder. It's what triggers the key-in chime, to remind you not to leave the key in the lock cylinder when you turn the ignition off. :lol: When the key in switch isn't closed but the ignition switch shows a position other than OFF, that code sets.

It's a pretty harmless code, especially if it's not resetting right now. I've often seen that fault associated with aftermarket remote start systems. Not saying your truck has remote start, just that there are ways of setting that code other than part failure. In short, I wouldn't worry about it.

Since I don’t know how to diagnose, I decided to be a parts changer. I bought a new MAF, Fuel Pressure sensor, Runner control valve, and Fuel pump module. So now I have all of those parts. Which one do you think I should try first, what do you think is the most likely culperate?

None! I hate 'trying' parts for a long list of reasons, not the least of which is the poor quality of aftermarket parts these days.

Fuel Rail Pressure Sensor and FPDM - Not likely? I think it's more likely that P0193 and P1235 were set when the previous owner were trying to diagnose this problem. :silly: I honestly don't recall - have you compared your fuel pressure gauge reading to what the pressure sensor says, KOEO? If they agree, I'd say the pressure sensor is doing its job. And based on your pressure sensor readings at WOT, I'd also say the FPDM and fuel pump are working well, too.

IMRC - You got this one fixed.

MAF - Still possible. Have you tried going for another WOT run after you fixed the IMRC issue? I'd be interested to see what the MAF is saying now. If it's improved (and closer to the known good values), then I'd worry less about the MAF. If the readings are still low, we'll leave MAF on the list of suspects.

Chapter 8 about 30 minutes in, any vehicle with a MAF sensor does not have an EGR valve. Some chevy and other designs may have a MAP sensor and a MAF, but Ford does not.

www.scannerdanner.com/scannerdanner-prem...ressure-sensors.html

I did find an EGR pid on the Verus. Sometimes I find things that don't work on my truck, but this one would allow me to control it's percentage rate under functions. I didn't mess with it, but it was there. Which is a pretty good indicator that it does control something, probably EGR related. What do you think it is for?

I told you I wasn't going to stop looking for it

Anyone have any suggestions on what may be causing my lean codes????