mavrik2747

Yeah I didn't even think of that. Also Torque only reads Fuel Rail Pressure (relative to manifold vacuum), doesn't pick up the rest.

F150Torqued

@mavrik2747 - I been thinkin'. /// Look out - that usually spells trouble ///


I subscribe strongly to 'challenging' sensors in unusual and creative ways to build all the forensic test data, or 'constants', that I can before attacking a DTC with expensive parts. I was about to suggest Torque monitoring your Fuel Rail Pressure (which we know is 'relative to intake vacuum'), and unplug injectors until the engine died. Then there would be NO vacuum, thus no 'relative' adjustment to fuel rail pressure reading - and you could see absolute pressure and how quickly it bleeds off, ie: if a leaky injector. BUT, the fallacy in that crazy idea is, I have NO IDEA how efficiently the Fuel Pump (common to the whole test) holds back-pressure!

@LaMartian, or anyone else, may have some knowledge about that or be able to shed light on it, if so please do.


I know that the PCM uses input from MAF / IAT in calculating Fuel/Air ratio - adjusting it by adding short term fuel trim plus long term trim on top of a manufacturer's base injector pulse width - then monitoring O2 readings for proper Stoichiometry (that's some $2.50 word for fuel/air ratio). P0172 says the PCM's UNABLE to maintain proper mixture without adjusting some parameter beyond SPEC limit. In this case, shortening bank 1 injector pulse widths beyond the LTFT limit (<25%).

We spoke about MAF readings in your above freeze frames. You noted the second one was lower and I mentioned that I have no idea about Grams/Sec - (AND STILL DON'T). But I decided to set up the attached Torque dashboard set of gauges - and try to replicate the scenario in your second freeze frame to give you a frame of reference. SHOOT! As you might know, Torque displays air flow in CFM when configured for US MILES, GALLONS etc.


So, I added a custom PID to display "RAW DATA" directly from the MAF sensor in base/10 digital numeric, next to several other readings in your freeze frame. Then I started my truck and let it idle till coolant temperature was about where yours was and grabbed a screen shot (attached below). STILL NOT SURE WHAT MY Tst-MAF reading means - but I do know you can replicate it - and compare it to yours if you like.
If so, the 'custom PID' set up is as follows: go to Settings, Manage extra PIDs'/Sensors, Add custom PID: then


Mode and PID = 221671
Long name = Test MAF
Short name = Tst-MAF
Min = 0
Max = 65535
Scale factor = x1
Unit type = Raw GM/S
Equaton = (A*256)+B
Header =
Diag Start cmd =
Diag Stop cmd =


The raw GM/S reading bobbled around between 681 up to 700 at idle. I have NO IDEA what formula the PCM uses to convert that reading into grams per second (nor we shouldn't speculate) how to compare that reading to either my CFM reading - or gram/s in either of your freeze frames. NOR the reading for MAF 'Volts' from the diagnostic reference charts attached to post # 8 above. Unfortunately, it would ONLY me meaningful if you set up the same PID and compared your RAW reading, uncontaminated by some formula.


Faulty injectors are hard to isolate if you can't find evidence in the plug tips. I still think your most 'conclusive' / 'low cost' diagnostic procedure (that should be fairly 'conclusive' since bank 2 seems to be behaving) would be to swap all injectors from bank 1 to bank 2, cylinder for cylinder, and see if the DTC follows the injectors.


If it does - I'd change the entire set. If not ----- heaven forbid --- it would suggest misfires (on bank 1 only) or an aspiration or breathing problem on bank 1.

mavrik2747

So I set up Torque the same way and here are my 2 readings, the first is at idle, the 2nd is at highway speeds, 55-60 mph.

The one thing I did notice is that the intake temp was about 15 degrees higher than the temp reading from my dash.

mavrik2747

I'm going to pull my plugs on bank 1 and swap out my injectors tomorrow.

F150Torqued

I am impressed - you set up a Torque Pro dashboard identical to the one I created. You are off and running now. Just do a "Torque Scan", and email the results to yourself to find ALL the PIDs your ECU responds to. Then have lots of fun!


On a more serious note, trying to stay "on point" - you are correct in noting IAT is much higher than the instrument cluster. This is normal. Note that mine was 95º. And it's not EVEN that hot in San Antonio now. Apparently that black plastic intake duct picks up lots of under hood engine heat. I've seen mine reading 120º in traffic. But in the morning, before startup - it will match out outside temp as displayed on the instrument cluster. I also notice your idle RPM was less than mine, and THAT offers a plausible reason for the GM/S reading being somewhat less than what mine was at slightly more RPMS.


Something I do notice however: The "Highest Value" readings on your Fuel Rail Pressure is 54.6 and 52.0 respectively. ?????? I went back and checked ALL FOUR screenshots I captured on my phone that day. Not a single one of them have "Highest value" for Fuel Rail greater that 42.6. In fact all four are exactly 42.6, even though other readings varied wildly with engine RPM, speed and so forth, during the 'rather long' engine run cycle.


While I am MOST interested in seeing the results of your efforts this weekend, I am also curious about this Fuel Rail reading and intend to watch "Highest Value" on my fuel pressure under varied conditions the next couple of days. This COULD suggest potential corrosion or impending problems with your Fuel Pump Driver Module. They are prone to corrosion & failure. And (FLAKEY) high fuel pressure indication would result in the PCM response of reducing injector pulse width to compensate - [ie: negative short term fuel trim which migrates into Long Term Fuel Trim]. {Agreed, the effect would be common to both banks, but both of your banks have exhibited slightly negative LTFT and there could be a second issue further aggravating bank 1}


When you complete your plug / injector efforts this weekend, I hope you will do a battery disconnect and relearn procedure to clear out all old compensation parameters from the ECU, and start a-fresh. Then post your findings.


Good luck

mavrik2747

So good news! Replaced the injectors on bank 1 and so far the P0172 code hasn't come back yet, and all of the fuel trims have been within tolerance so far, but I haven't driven it very much yet. I did a battery relearn and everything looks good.

As for the air intake temp, makes sense, that the black plastic would heat up the air from the engine heat.

I'll keep an eye on the fuel rail pressure, I looked at it momentarily yesterday and this morning and pressure was around 38-40, but I didn't pay attention to the highs and lows, I'll do that on my way home today. I've already replaced the FPDM, so hopefully it was just the worn down fuel injectors, but I'll report back on what I find on the pressure.

As for the Torque App, I've gotten the hang of it pretty well, but still am a novice on how to properly diagnose things and I'm sure there are still a ton of stuff on it that I've just barely scratched the surface. I just loaded a custom tune from PHP and think I might be running into an issue with the Torque App.

I bought an OBDII splitter, and Torque won't run with my Gryphon simultaneously, so I just loaded my custom tune, unplugged it and leave the Torque connected. I get all my readings except for misfires on the real time info, when I was previously getting them on start up on both banks. Also my test results don't complete either, so I can't go in there and check anything. So I'm thinking I probably need to switch it back to stock or a can tune, for some reason it's not reading everything with the custom tune.

I will say that the custom tune is awesome! Shifts so much more smoothly and the performance is so much better. Still getting a slight misfire in OD at 55 mph or so, but overall performance is so much better.

F150Torqued

That's good news.


I put up the above Torque dashboard screen yesterday on a longer drive cycle - and at the end I noticed that Highest Value fuel rail pressure was 44.6 and lowest was 38.7. I also noticed that my "Raw GM/S" was still 'slightly higher' (500 +-5) than yours even though my idle RPMs were lower (600 +-5) at full operating temp (195º). May mean nothing, IDK, as there remain several other variables - (including Rail Pressure sensor, the fuel pump itself, calibration of the MAF sensor - or even the effect of a Tune). As you properly suggest - just keep an eye on it and consider it in analysis of any further symptoms.


As for the Tune having an impact on Torque or any scanner or its readings, I can say with certainty, having a process control programming career in my rear view mirror, that modifying one routine in a process control program can have a bearing on other routines. Even an unexpected effect! Without benefit of the source code and programmer comments -- I don't even see how they can reverse engineer things sufficiently to create a custom tune.


Don't sell yourself short in diagnosis. There is plenty of evidence all through the forum of snap diagnosis based on one DTC or scanner reading - even among seasoned mechanics.


Good Luck, and I hope that "P0172" is HISTORY!

nnuzzo141

Sorry to bring up an old thread but I've been trying to diagnose the source of me rich codes for awhile now. I've been running rich on both banks and also have a p0451 code for emissions. From my understanding they are unrelated but I'm not 100% sure on that. So far I've replaced or checked the following for correct operation: oxygen sensors, MAF, all injectors, and intake manifold. I'm at a loss with what to do now. My gut tells me it's the fuel pressure regulator on the rail but when I checked that it was dry. I'm going to change it since everything else is new but if someone can give me some input that would be really appreciated because I'm running out of ideas and my knowledge on this has reached its end. Thanks in advance everyone

Hongstertruck

Do you have a K&N air filter? If you do then remove it and clean your MAF.

nnuzzo141

i do have a KN, I already tried cleaning the MAF which had done nothing and then tried swapping it with my friends truck which is the same as mine, also did nothing