Mil - P0171 + P0174
I have this vehicle at my shop and giving me a big headache now and starting getting to the point where I feel like I'm starting to spend money from my pocket.
It have check engine light with DTC P0171 & P0174.
STFT B1 : +12
LTFT B1 : +25
STFT B2: +7
LTFT B2 : +25
- MAF Sensor, Both Upstream Oxygen Sensor, EGR Valve, Fuel Pump, Intake Manifold Gaskets, PCV Valve & Hoses (All Motorcraft Items). I checked for vacuum leaks on cold engine erly in the morning but did not find anything.
Perhaps you should let us know when the fuel trims are lean (idle,2500,under load). what vehicle? What tests have you Done? Etc...
Fuel Trims at idle STFT B1 : +12 LTFT B1 : +25 STFT B2: +7 LTFT B2 : +25 If I rev the engine and hold at 2500 RPM then LTFT come down and STFT rises to around +25
With trims being lean both at idle and off idle, I do not suspect a vacuum issue What is the MAF reading at idle? Have you measured fuel pressure?? Have you performed an Ethanol / Water separation test on the fuel?
Hello Chris. I have check the entire system properly for leaks and I did not found anything. (Cold Engine). I have also checked the fuel pressure and made sure pressure do not drop after turning the key off. MAF Sensor is also new but I'll get the reading in few seconds and post it here for you. Thank You
Herein lies your problem, you are out looking and searching for the problem. If you would let your scan data lead you to the problem, life would be a lot easier. If you would like me to explain how this can be done, I would be glad to do it. You will need a scan tool that will make a data capture and can display the data pids in a graph. Let me know, and I'll try to help you do this job the
Hello Albin. Can you please help me with this problem because I'm starting to pull my hair from head.
Here are two different posts I have put up here on DN about this subject. Read them over and get back to me with your questions. You can give me a call if needed … diag.net/msg/m6dd30cz5z… diag.net/msg/m385mqlbos…
I agree with Albin. We need to see data as it is trending in a graph. Read the links he posted. It is great information.
Can you please supply year, make, model, and engine size?
I'm sorry. Its 2004 Ford Explorer 4.6L Eddie Baur.
2004 Ford Explorer with 4.6L
Hi there Arsalan have you check this TSB out
Hello Edward. I did check this TSB while I was talking to the tech on identifix hotline. We did the injector pulse test and all test out okay with same specs.
Whats the drivability of the vehicle when driving beside the check engine light on.....
Vehicle drives normal. Can't even notice any problems that how it drives. Only concern is that customer do not like to see check engine light on dash.
Hello! Was the fuel filter replaced with the fuel pump? Was the condition of the fuel check ? Do you have anyway to check to make sure you are getting the correct volume of fuel? Chris
Hello Chris. Yes I did replace fuel filter. Fuel pressure on gauge I'm reading is about 63psi and drops to 55 after shutting down the vehicle for 10 min. And volume is fine aswell.
Did you compare a fuel sample to a new fuel sample? Maybe water or to much ethanol or other contaminates.
Hello Chris. Yes I did do the fuel sample test and also I checked for ethonal while I was talking to the identifix on hotline. It test out to be okay and he also made me remove all the fuel out and add fresh fuel in there but we still have the same issue. Identifix also made me replace PCM and program but still same issue.
Have you done a VE test? If so, what are the readings and how exactly did you perform the test? We have to look at this logically - both banks are running lean and they are lean at idle and off idle. This would rule out anything that affects only one bank and anything that would only affect fuel trims at low or high rpm (O2 sensors and vacuum leaks) and we would need to concentrate only on
Hello. I have not done the VE test. My MAF Sensor reading at idle is 4.74 (gm/S) & 0.98V (2500 RPM readings are 16.85 gm/S & 1.77V)
Were all of these parts for this issue or have we already repair some other concerns? Make sure the air filter is the right filter, the V6 filter is shorter and will fit in the airbox. This can skew MAF readings.
YES all of these parts were replaced because of DTC P0171 & P0174. I checked the air filter its about 2 months old and looks good and correct part and size.
How did you check your fuel volume, do you have a fuel volume guage?
Hello James. Customer needs to talk to his personal mechanic first, Because I have told him to drop the vehicle to my shop for proper diagnostic. He was wasting too much of his money by listening to someone else who calls himself a mechanic. Will come back and update with more info once he drop off the vehicle
Good afternoon please perform volumetric effecicency test and post results. I think this will lead us in the correct direction!!
I had same issue on a honda pilot today. Clogged fuel injectors. I performed wynn's cleaning but same problem. Rreplaced injectors and fuel trim returned to normal. If stft is lean at idle and above idle suspect fuel issue. If pressure is good and fuel not contaminated probably injector issue.
Hello Ryan. I will let the customer know about this test. He bring vehicle to me every two days after talking to his personal so called mechanic
Were you able to get decent history, per chance? I'm wondering about things like: Did the car just suddenly "do it" after years of trouble free operation?, or did they just buy it (like this). e.g. I'm thinking if the injectors aren't simply old and evenly clogged, they could even be wrong for the application, if someone has "been in there" before the truck came to you. No need to respond…
Going to start with some basic info needed: Baro reading? Either Hz or psi reading is fine What’s your elevation? Fuel pressure at idle and under load while accelerating? MAF @ idle and WOT under load and at what rpm? DPFE sensor reading at key on and idle? Manifold Vacuum in Hg? O2 sensor switching range? Hose from breather tube to valve cover connected? Lot of other things I want to ask but
If u have fuel trims high at all rpm ranges could be wrong Injectiors ,,
If there is an issue with the injectors I would suspect the FuelPW PID (injector pulse width) should be excessive. Expect normal readings about 3.5 ms at idle for this truck and 5ms or so 25 mph cruise
I have talk to customer about leaving the vehicle in my shop for proper diagnostic, I guess he needs to talk to his personal mechanic first since he was telling all this time to owner to change this and that. Will come back and update if he drop off the vehicle with me.
Not sure if you fixed this one, dd you check the purge valve, sometimes they stick open causing a lean condition, can you confirm its lean, using a gas analyzer, did you reset your KAM, Fords get stuck with old memory even after you repaired the vehicle