Zero LTFT B1?

Elisha Technician Odessa, Texas Posted   Latest   Edited  
Question
Driveability
2005 Ford F-150 Lariat 5.4L (5) 4-spd (4R75E)—1FTPW12505FB22521
P0174 - System Too Lean Bank 2
Sluggish At Acceleration
Zero Ltft B1

I was trying to diagnose the P0174 when i noticed the fuel trims not right. Specially LTFT B1 no change whatsoever at any RPM. I am puzzled by this, make's me think PCM is malfunctioning. I have tried resetting the KAM and still the same issue. Driving it or upon acceleration STFT numbers stay around the same -3.6 to +4.8. Long term on B2 tries to adapt. I also have O2 sensor readings and it makes me think that CAT on B1 is plugged. Since B1S2 is mimicking the upstream. Don't know any help would be appreciated. Thank you.

0
Daryll Diagnostician
Seymour, Tennessee
Daryll Default
 

If sensor 2 is matching sensor 1 then the cat isn’t plugged, it just isn’t doing anything Did you do a code clear and KAM reset? If KAM reset was successful but the problem was still present then you should see fuel trims start adjusting immediately

+1 Default Ð Bounty Awarded
Elisha Technician
Odessa, Texas
Elisha Default
 

Yes i did clear the codes and did a KAM reset. Still the same symptom. Fuel trims adjust except on LTFT B1.

0 Default Ð Bounty Awarded
Ray Diagnostician
North York, Ontario
Ray Default
 

The P0174 is bank 2 too lean. In the Freeze Frame, what is the ECT, what are the fuel trims for both banks and the RPM. If the code sets at idle, then smoke the intake. If the code sets while cruising, you need to check fuel pressure and volume. Ck for a split intake boot, the wrong air filter, a plugged air filter, a damaged air filter housing or dirty MAF. Do a Search In Diagnostic Network…

+1 Default Ð Bounty Awarded
Elisha Technician
Odessa, Texas
Elisha Default
 

I was not able to retrieve FFD on this with my scanner. I have noticed i cannot do it on Fords, on other vehicles i can like Chevy. And i don't have an IDS available. I did not check the ECT temp at the time of diagnosing. Fuel trims do not change at idle which is around 600-900 RPM and at … I drove the vehicle and still no change. Vehicle entered CL. Forgot to mention that i replaced…

0 Default Ð Bounty Awarded
Albin Diagnostician
Leavenworth, Washington
Albin Default
 

Will the both oxygen sensors react enrichment and enlienmsnt? Are both banks running in closed loop? Since the fuel trim comes directly from the oxygen sensor data, they need to be verified for proper operation first. If perchance the sensors will not respond, then fix that problem first.

+1 Default Ð Bounty Awarded
Chris Technical Support Specialist
Commack, New York
Chris Default
 

Ford should have a pid for Fuel System or Loop. When the O2's don't respond as expected it may put the system in closed loop fault, on IDS it will read CL-Fault. This can happen when one O2 sensor fails to provide a correct signal.

+2 Default Ð Bounty Awarded
Elisha Technician
Odessa, Texas
Elisha Default
 

I have not tried to add propane to the system. I believe the sensors maybe working. Kind of sketchy of B2S2 though.

0 Default Ð Bounty Awarded
Elisha Technician
Odessa, Texas
Elisha Default
 

Sensors are working properly i believe. Created a vacuum leak at the Brake Booster and all the 02 sensor reading's dropped.

0 Default Ð Bounty Awarded
Matthew Mobile Technician
Bartlett, Illinois
Matthew Default
 

Check your loop status. Closed loop fault will have both bank trims the same, it uses the bank the PCM thinks is "good". Open loop fault you will see default values sometimes for LTFT, but STFT is usually 0. HO2S data is your best friend when the trims are in open loop fault.

+2 Default Ð Bounty Awarded
Elisha Technician
Odessa, Texas
Elisha Default
 

I am unable to check the other or the rest of of the OL/CL PIDs. Since i do not have an IDS.

0 Default Ð Bounty Awarded
Matthew Mobile Technician
Bartlett, Illinois
Matthew Default
 

Most of the aftermarket scan tools I have used list it the same as IDS.

0 Default Ð Bounty Awarded
Jim Curriculum Developer
Frederick, Maryland
Jim Default
   

Plus one on the two gentleman mentioning loop status. Too many people think there are two (open and closed) when there are five.

+1 Default Ð Bounty Awarded
Matthew Mobile Technician
Bartlett, Illinois
Matthew Default
 

Yes - and Ford just does a better job clarifying in their scan data.

0 Default Ð Bounty Awarded
Geoff Diagnostician
Lahaina, Hawaii
Geoff Default
 

You should write/post an article on that, Jim. Sounds interesting.

0 Default Ð Bounty Awarded
Albin Diagnostician
Leavenworth, Washington
Albin Default
 

That is one of the benefits of using Ford enhanced data over OBD2 Generic data. The 5 different versions of loop status give a lot of cool pointers as to what is going on with the fuel control. I can remember back when Ford first got data stream, it was like pulling teeth to get data that actually worked and was useful. Then someone flipped a switch and the switch with the data. When OBD2 came…

0 Default Ð Bounty Awarded
Matthew Mobile Technician
Bartlett, Illinois
Matthew Default
 

I did one awhile back: members​.​iatn​.​net/forums/read/ms… From that post: Open Loop - Drive, also known as fuel enrichment, occurs during heavy acceleration and WOT. On a two bank vehicle Closed Loop - Fault is when one bank O2 sensor or A/F sensor has a fault. This can be caused by a bad sensor or by one bank being extremely rich or extremely lean. The vehicle…

+2 Default Ð Bounty Awarded
Geoff Diagnostician
Lahaina, Hawaii
Geoff Default
 

Thanx Matt!

0 Default Ð Bounty Awarded
Jim Curriculum Developer
Frederick, Maryland
Jim Default
   

Open loop fault can be caused by more than exhaust gas sensors but the general concept is solidly explained. We rarely see OLD on modern systems using wide band sensors compared to the past. Ford is not the only ones to recognize the five states of fuel control. I think a little research will show it is in the J standard for OBD data. Toyota teaches it as well.

0 Default Ð Bounty Awarded
Elisha Technician
Odessa, Texas
Elisha Default
 

Thank you Matthew. This is good info i will have to check it out.

0 Default Ð Bounty Awarded
Elisha Technician
Odessa, Texas
Elisha Default
 

That is very interesting! I did not know there were that many Loop status. Thank you.

0 Default Ð Bounty Awarded
Daniel Owner
Long Beach, California
Daniel Default
 

I had an issue with a 2002 f150 with lean code Cant remember what bank was it..but it was giving me a code for closed loop fault.. and it was the o2 sensor also make sure the thermostat its not stuck open..

+1 Default Ð Bounty Awarded
Caleb Technician
Mishawaka, Indiana
Caleb Default
 

You should be able to view freeze frame data in the generic/OBDII side no problem. I have the same scanner just go thru the OBDII tab.

+1 Default Ð Bounty Awarded
Elisha Technician
Odessa, Texas
Elisha Default
 

Thank you Caleb. Did not know that. Too bad i deleted the DTC's. No DTC's have come up since.

0 Default Ð Bounty Awarded
Elisha Technician
Odessa, Texas
Elisha Update
 

Started the truck up today. Still doe's the same thing. I noticed the fuel trims actually somewhat working now. It is sluggish,bogs down and sounds like it is misfiring @WOT.

0 Update Ð Bounty Awarded
Caleb Technician
Mishawaka, Indiana
Caleb Default
 

Not trying to make a silver bullet here but I would check the spark plug gaps. Does it smoke at all on acceleration?? Verify base timing by scoping cam an crank. Also look at VVT data to verify it's working properly. If it's not going lean on hard accel indicating a lean condition I personally would be having a look at the plugs. Your 02 data doesn't look like clogged cats. Although no harm in a…

0 Default Ð Bounty Awarded
Elisha Technician
Odessa, Texas
Elisha Default
 

Caleb. I think you may be on to something here. I just remembered that i had a vehicle with bad plugs in it and you really couldn't tell it was misfiring at idle or while driving. I know it sounds weird. I will have to check them out but, I am really not looking forward to it. It's a TRITON...

0 Default Ð Bounty Awarded
Chris Technical Support Specialist
Commack, New York
Chris Default
 

I have had the best luck with this OTC tool. tooltopia​.​com/otc-tools-6918… The center piece clamps on the metal end and locks the porcelain to the outer sleeve that turns the hex. It will give you that extra little bit that helps keep it together. If you combine this with a bit of penetrating oil, after barley cracking the threads loose, and a few hours of soak time it typically…

0 Default Ð Bounty Awarded
Caleb Technician
Mishawaka, Indiana
Caleb Default
 

Chris is correct also I've had really good success with getting the engine hot an using a 3/8 impact on the plugs.

0 Default Ð Bounty Awarded
Elisha Technician
Odessa, Texas
Elisha Default
 

Thanks Caleb for your input. Just as i said i remembered a similar situation a couple weeks ago. It was the SPARK PLUGS. Swapped them out and Runs like a CHAMP!

0 Default Ð Bounty Awarded
Elisha Technician
Odessa, Texas
Elisha Default
 

Oh yeah it's a MUST have for every Technician.

0 Default Ð Bounty Awarded
Elisha Technician
Odessa, Texas
Elisha Update
 

Well the problem was solved thank God and ALL of you who gave your opinion and feedback. In the end it was bad Sparky's causing the problem. It is weird for me this being the second time it happened to me. I did not bother thinking of that yet, until one of you mentioned it. I really appreciate the HELP to EVERYONE. I was able to learn some stuff from You all. I hope to maybe give my input one…

0 Update Ð Bounty Awarded