P0171 and P0174 2006 F250 5.4L 3v

Hello, my name is Rex.

I could use some assistance with diagnosing my vehicle problems, please? It is a 2006 Ford F250, 5.4L 3v, Regular cab, XL, Long Bed.

I have two codes P0171/p0174. In addition, temporary codes of P0193, p1235, p2006, p1000. Should I test all these parts, not sure how to test the pump over current? The vehicle maybe has a bad vent valve (snap on reports that is common for the no fueling problem). Not sure if that caused the fuel pump out of range or if that is a real no signal problem that is maybe intermittent, since the vehicle runs and the pump is pumping? The check engine light is on for the lean codes only. The vehicle runs really rough intermittently and at idle and very rough on acceleration. Seems to smooth out about 3,000 rpm but still runs lean. Never equals out to zero. 02 sensors reads lean (down) on wot test.

Not sure if this is relevant but there is no code 10 data, its blank. Even with the check engine light on, no code 10 data. The link is there to check for it but comes back with no codes. The misfire data is showing no misfires. One of the checks revealed a couple misfires but it was like 1.254 or something really low. Nothing in the hundreds or thousands. When I cleared codes those went to zero after check was run. Did a diagnostics check and this is all the info I have.

I have done several WOT tests and ST tests and saved the data but don't know how I could send it as my scanner does not connect to the internet, and I don't know your email address. On all WOT tests I had a 15% improvement on the LTFT and 02 read lean signal, but the short term increase by same amount or more. When reving to 3000 RPM and holding, there is no long term improvement and seems to get worse.

After reviewing the WOT data, there seams to be a 15% improvement on all the WOT tests for long term trim but the short terms also are higher and do not have an overall improvement. Does this mean a possible vacuum leak even though I have sensor codes? I did not smoke test it but sounds like I should do that next or should I look at sensors or the temporary codes first? On all the WOT tests the 02 reads lean on take off and around 2500 rpm jumps up to rich and then back down to lean until throttle is released. All tests this same event occurred. Not sure if that means an intermittent problem or if that's what it is supposed to do or is relevant? To clarify, 15% improve on WOT test for the long term fuel trim but 15% or more higher readings on short term trim. Overall it gets higher fuel trim reading and no improvement. If you just consider LTFT it has 15% improvement. Only on WOT test and not constant high RPM rev above 3,000 rpm. Smoke test time? Maybe internal vacuum leak test? Or is this not a vacuum leak becuase the overall fuel trim did not improve and did not improve at high idle test?

Here is what I have done thus far:

I removed the MAF sensor and inspected it, it was very clean and likely new. I was told by previous owner the plugs, fuel pump had been replaced. I replaced fuel filter. Fuel pump has 70 psi KOEO, did not test while running because its a 2006 F250 5.4L 3v and I don't have the adapter to read fuel pressure while running. I did a carb cleaner check for vacuum leaks and also pinched all the hoses, including break booster check (inside and outside). No change. I checked the rods for the runner valve and they are connected. I don't understand if both rods are connected how it could possibly stick on bank one and not also on bank two. They are connected by metal rods????

Should I start with smoke test or internal intake leak test or sensor checks or injectors or could this be a bad computer driver or ac overload from alternator? Not sure which way to go here.

Not sure which codes are relevant and which parts I should check next or which tests to run? Any assistance would be greatly appreciated. I do have a verus scanner to get live data and limited scope tests. It is my knowledge and experience that I am lacking.

Thank you,

P.S. I wanted to add some information that may be useful. The when wot test initial acceleration to full peddle, there is a couple second response time.

Not sure if this will factor into the equation, but I have a pulse width modulation signal fuel pump. Verus notes say that may cause drivability issues under 3,000 rpm.

Hey RexPE1! Did you happen to save your scan data captures on your Verus? If so, you can send me the .SCM files and I can review them on ShopStream Connect.

I checked the rods for the runner valve and they are connected. I don't understand if both rods are connected how it could possibly stick on bank one and not also on bank two. They are connected by metal rods????

You're checking the IMRC rods because of the P2006 code, correct? That code description is a bit misleading. :lol: It says 'Bank 1', but in reality, both banks are controlled by one actuator. The PCM can't tell if one bank is stuck, or both. All the PCM knows is that the IMRC actuator didn't send the correct feedback signal when the actuator was commanded to move the intake runners.

Fuel pump has 70 psi KOEO, did not test while running because its a 2006 F250 5.4L 3v and I don't have the adapter to read fuel pressure while running.

Not sure if this will factor into the equation, but I have a pulse width modulation signal fuel pump.

No adapter required. As you noted, this is a PWM fuel pump. That means you can use the FRP (measured fuel pressure) and FRPDSD (desired fuel pressure) PIDs to watch pressure during at WOT run. Try to make the WOT run as long as you safely can. All the way through 1st AND 2nd if possible.

Should I start with smoke test or internal intake leak test or sensor checks or injectors or could this be a bad computer driver or ac overload from alternator? Not sure which way to go here.

Vacuum leaks are certainly possible, but that would not be my first guess. An alternator problem is not high on my list of suspects, either. I'd stick to the scan tool for now and try to get as much information out of it as you can.

If you can save a capture of your WOT run with the FRP and FRPDSD PIDs along with fuel trims, engine speed, MAF, engine load and the upstream O2's, that'd give us a much better idea of what's going on.

I will look for those pids on my verus and do another WOT test. I do have all the tests saved on my verus but not sure how to post them here as the verus does not have email. I could maybe save to a thumb drive if I could figure out how to do that. I will look into that. I was reading over the Mitchell 1 troubleshooting for the P0171 lean code and one of the possible causes was listed as the Fuel Rail Pressure Sensor. FYI. I do not know what those reading are supposed to be for that sensor or where to find them on the live data pids, if they exist, but I will research all of that and post the results here, even if I cant post the actual files. Maybe a pic with my phone? I could do that and post the reading through the WOT test.

I dont see the pid for FRP and FRPDSD. I looked on both global and manufacturer pids. I found Relative fuel pressure 40 psi at idle with min max 35-42. I also noticed that two of the snap throttle tests the pressure went down when the rpm and demand went up. One of the snap throttle tests the pressure went up with demand and rpm.

Fuel level input at idle 21.6, min max of 21.6-22.4. IMRC1M(V) stays at 5.11 volt through Snap Throttle, IMRC1M stays at 5.11 volts through snap throttle. IMRC stays at OFF condition through snap throttle. I imagine this is supposed to move to on at some point in the throttling acceleration?

If there is a pid for fuel rail pressure, can you tell me what it is called on the verus? Where it is located in global or manufacturer? Can you post a pic of one you have saved from another Ford? Maybe that would help me find it. Thanks

I will keep looking for the pids for the FRP and FRPDSD

I did eventually find them and did some snap throttle tests and will do an WOT and post them when done.

Update on pids for WOT test. I did the test you suggested, but do not know how to post pics or videos.
FRPDSD desired fuel pressure is 40psi constant through wot and at idle and during ST tests. Never changes
WOT test results:
700rpm/idle to 5100rpm results:
FRP V min max is 2.45 3.3.
FRP psi min max 40 - 44.9 w/ min at deceleration at 33.7
LTFT idle bank 1-24, bank 2-17 - at 5k rpm bank 1-16, bank 2-20. Stays around the high numbers through the wot throttle test
STFT idle bank 1-5, bank 2-6 - at 5k rpm bank 1-43, bank 2-39
FP% at idle 20%, full throttle until 5k rpm 32%
O2 bank 1 & 2 -lean on throttle up and normal cycle at idle, has slight signal to rich around acceleration 0.05, goes rich for a second at 2750rpm then immediately back to lean signal until throttle is released.
Baro inHg at idle 27.4, 1600rpm 27.1, 5100rpm 27.4, 5100rpm 28
Baro Hz at idle 151, at 1700rpm 150, 4100rpm 151, 5000rpm 153
LOAD% at idle 23.7, 950rpm 61.3. stays about there until release of throttle, comes down a bit at higher rpm, 5100rpm 49.9%, deceleration to idle 12%
MAF V 0.97 at idle, initial throttle 1.86 rising to 4.01 at 5100rpm
MAF G/S at idle 8, raises to 182 at 5100rpm

I am curious about the FP% readings. I just watched a couple videos where Danner explained this fuel pump system stating that 25% duty cycle is an off command and 50% duty cycle is full on. 20% at idle would then be completely off and below the 25% duty cycle. Unless some of the info is wrong and the FP is not duty cycle or the 25% is not off, on my vehicle???? That was a 2002 Taurus with same fuel system. Danners brother said FP% meant duty cycle. So that is where I got that idea from.

Not that anyone is replying but I have an update anyways. Replaced the MAF sensor with a new one. Much improvement but still ran a little rough and ran lean only at higher rpm this time. The lean condition at idle is completely gone. I figure Oreilly's gave me a bad MAF. Any opinions on this?

Sorry Rex, not trying to leave you on your own! :blush:

Glad you found the FRP and FRPDSD PIDs. FWIW, I dug up some data from a known good '07 F-150 5.4L I worked on previously:

Replaced the MAF sensor with a new one. Much improvement but still ran a little rough and ran lean only at higher rpm this time. The lean condition at idle is completely gone. I figure Oreilly's gave me a bad MAF. Any opinions on this?

Wouldn't surprise me that a parts store sold you a bad MAF. :lol: Just for educational purposes, it might be fun to do another WOT run while looking at the MAF g/s and voltage. See if the peak airflow improved.

Lean at higher RPM is still an issue. If you do a test drive and save the capture, it gets stored as an .SCM file on the Verus. Don't ask me where, I don't know exactly. But if you can dig it up, you can send it to me at wrenchturnsyou@gmail.com.

IMRC1M(V) stays at 5.11 volt through Snap Throttle, IMRC1M stays at 5.11 volts through snap throttle. IMRC stays at OFF condition through snap throttle. I imagine this is supposed to move to on at some point in the throttling acceleration?

Correct. I don't think you'll get this system to cycle during a snap throttle? Again, known good shows the IMRC only comes on under select conditions:



The easiest thing to do may be to use the KOEO Self-Test (under the Codes menu on the Verus) while watching the IMRC arms with a mirror. The PCM will actuate the runners during the self test. If you see some movement of the arms, you can be reasonably confident that power/ground/signal are present at the IMRC actuator. If you see zero movement, you may have an electrical issue.

WOW great data. The fuel pressure seams to be a couple psi below mine at 40 psi. All pids look same as mine except my FP% duty cycle never goes above 23% during snap throttle and my (new) maf is highest at 3v. Does reach 4v in wot test. My map sensor reads high around 182 during snap throttle and wot. So that is a bit lower. I had better maf voltage with the old maf sensor. My readings now (w/new maf) seem to be typical bad maf readings (I just finished watching chapter 12). However, I am not ruling out fuel pump or injectors and am not replacing maf until I run more tests.

I planned on doing a running fuel pressure manual test to see if the pressure matches what the verus says, under idle and during snap throttle only. Cant view pressure gauge while driving. Also, I was wanting to check the injector pressure bleed down test, to see if the injectors were pulsing a different amount? I would like to get a pulse width reading on the injector pulse, but don't know how to connect the wires. I think I can put scope wire on the inertia wire but don't know if that should be a low amp probe or just an alligator clamp to the yellow scope wire then monitor the feed circuit???? In addition, I plan on inspecting the plenum/air cleaner housing before the MAF sensor for possible leaks or bad seals. Actually, I would like to do all the tests in Danners classes, but just dont really have a place to conveniently work on my truck.

Danner helped me with the IMRC open closed. I did see it open but it only opens when under full demand, throttle.

Great suggestion on how to physically check the runner valve for opening. Good point, the computer could be requesting it on, it thinks its on, but it not actually be opening. Need to get a diagnostics helper for that one, so that test will have to wait a bit.

I know where the files are saved on the Verus, but do not know how to send an email from the Verus. No email app or account and Microsoft surely wont let me download one, haven't tried but I know now they are on software they don't support anymore. I could maybe connect online hardwired, wireless doesn't work good, and email from google mail web browser???? Maybe, I will try it. Thanks for the email address. That will help if you can actually see my test results.

I ran a new code scan, after reset for new maf, and now only have the two lean codes and the IMR valve stuck closed codes. Plus some kind of code for the ignition key???? I have no idea what that means???? The others may come back? So far they have not.

Mitchell1 Ford info says check the fuel pump DTC first before the pressure sensor. Also mentions duty cycle:
Diagnostic
Aids:
The FPDM sends a 25% duty cycle (250 ms on, 750 ms off) through the FPM circuit to the
PCM while the concern is being detected by the FPDM. If the concern is no longer
detected, the FPDM returns to sending an all OK (50% duty cycle) message to the PCM.
For ETC applications, check if ETC DTC P2105 is present. An ETC system concern could
cause P1235, and should be diagnosed first.

My duty cycle stays at 22-23%. Does that mean there is a fault? I do have the fuel pump out of range code. Could this be related to the sensor code and also to my lean on both banks codes?

RexPE1 wrote:

The FPDM sends a 25% duty cycle (250 ms on, 750 ms off) through the FPM circuit to the
PCM while the concern is being detected by the FPDM. If the concern is no longer
detected, the FPDM returns to sending an all OK (50% duty cycle) message to the PCM.
For ETC applications, check if ETC DTC P2105 is present. An ETC system concern could
cause P1235, and should be diagnosed first.

My duty cycle stays at 22-23%. Does that mean there is a fault? I do have the fuel pump out of range code. Could this be related to the sensor code and also to my lean on both banks codes?

Negative, your FP% readings are fine. The system description you found is talking about the FPM (Fuel Pump Monitor) circuit. For clarity, the FP% is the requested fuel pump duty cycle from the PCM. This is the value that the FPDM doubles and runs the pump accordingly. As in, the PCM signals 23%, so the FPDM runs the pump at 46%. The FPM is the circuit the FPDM uses to signal if there's a problem, and what the problem is (to an extent).

These are the normal values for FP%:



And these are the normal values for FPM:



Since P0193 and P1235 haven't come back so far, and your fuel pressure readings look good, I'd put those codes on the back burner and focus on your lean codes.

Plus some kind of code for the ignition key???? I have no idea what that means???? The others may come back?

Something about Key In Switch? Which module set this code?

I got your data captures, thank you! I grabbed this from day three after MAF:



I'm OK with the small changes in fuel pressure as demand changes. My other capture doesn't show it, but I have seen similar behavior on other good FPDM systems. If the fuel pressure dropped below desired and stayed there while under load, I'd be more worried.

I grabbed this from the day three WOT:



The MAF is reading a bit low at WOT, but that could have something to do with the IMRC system not working correctly. However, that doesn't explain the lean condition. Two separate problems, IMO.

Any chance this truck got filled with E85? :huh:

I just purchased this truck a few weeks ago, so anything is possible. However, I have run the tank empty, so if it was filled with E85 gas, there is none left in the tank.

I Ford mechanic on youtube said the Fuel Rail Pressure sensor could cause lean codes and could cause drivability issues. The pinpoint test on mithcell says to address any fuel pump codes prior to fuel rail pressure sensor. So I seem to be getting conflicting info.

So I think my only next option is to be a parts changer and put a new pressure sensor. The fuel pump out of range code makes me want to look at the FPDM but if you say it's fine, and the 18-23% duty cycle is normal, I will go a different way. The IMRV stuck closed may be an issue, but like you said, it's only used during wot and you stated it wouldnt cause a lean code. So I agree, I am going to look a different direction. If you don't have any suggestions as to what I should look at or what test to run, parts changer I will be. New FRP sensor. What do you think?

I am still keeping bad MAF as most likely cause. Only because I had drastic improvements from the new MAF and yet it still has classic bad MAF symptoms. Good fuel trim at idle, lean on wot test. Fuel pressure is reading normal, o2 go lean at wot test. Classic bad MAF, but like danner says, that's only a guide, other things could cause the same symptoms. Just not of the other options fit my symptom list.

I would think about an injector problem, but I put lots of seafoam and had zero improvement. If it were injectors clogged, there would have been a slight improvement, I would think????

The fuel pressure is at 40 psi, so that couldn't be causing my lean condition as that is the desired pressure. So I don't suspect fuel pump or FPDM. Unless the driver module also controls the injectors? Then that could cause lean codes and drivability issues. I have not seen that anywhere. Do you know if the FPDM has any influence in the injector pulse or control over the injectors?

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?

The reading where it is running lean at idle are from before I replaced the MAF sensor. It now has good fuel trim at idle and lean on wot and snap throttle test only. Idle reads good but still has a little mis at idle. I suspect maybe a coil isn't firing exactly perfect causing the slight misfire at idle???? It could also be related to my lean issue and sluggish acceleration at low rpm? Fuel trims now read good at idle, though. So that has improved with new MAF. Also, there was a slow response in throttle response, that has drastically improved with the new MAF sensor. Some of the hesitation has improved also with the new MAF.