Long term fuel trim out of wack.

[Starjammir]

Here we go boys..... 2020 ranger 60k
Had a CEL for 10k and ended up taking it in. CEL for O2 sensor heated circuit. Ford and myself have replaced that sensor a total of 8 times. Never fixed it. They replaced the O2 sensor. Didn't fix it. The replaced the cat, didn't fix it. Replaced the intake valves( for some reason) didn't fix it. Replaced the vacuum pump( again why?) Didn't fix it. I told them, check the wiring. They said they did. Ford told them to replace the harness, boom CEL off.
Now the fuel trims are at 11-13%. They have replaced the O2 sensor again( again why) didn't fix it. They are now thinking injectors, no CEL for anything however that's what they see on the scanner.
Any idea where to start? I should add this is all under my extended warranty so no charge to me.
Thanks all!

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[RangerBill]

Here we go boys..... 2020 ranger 60k
Had a CEL for 10k and ended up taking it in. CEL for O2 sensor heated circuit. Ford and myself have replaced that sensor a total of 8 times. Never fixed it. They replaced the O2 sensor. Didn't fix it. The replaced the cat, didn't fix it. Replaced the intake valves( for some reason) didn't fix it. Replaced the vacuum pump( again why?) Didn't fix it. I told them, check the wiring. They said they did. Ford told them to replace the harness, boom CEL off.
Now the fuel trims are at 11-13%. They have replaced the O2 sensor again( again why) didn't fix it. They are now thinking injectors, no CEL for anything however that's what they see on the scanner.
Any idea where to start? I should add this is all under my extended warranty so no charge to me.
Thanks all!

Positive fuel trims are trying to correct for a lean mixture. It is increasing fuel injector pulse duration to compensate. It could be caused by low fuel pressure, clogged fuel injectors, or a vacuum leak.

 

[diesel924]

Here we go boys..... 2020 ranger 60k
Had a CEL for 10k and ended up taking it in. CEL for O2 sensor heated circuit. Ford and myself have replaced that sensor a total of 8 times. Never fixed it. They replaced the O2 sensor. Didn't fix it. The replaced the cat, didn't fix it. Replaced the intake valves( for some reason) didn't fix it. Replaced the vacuum pump( again why?) Didn't fix it. I told them, check the wiring. They said they did. Ford told them to replace the harness, boom CEL off.
Now the fuel trims are at 11-13%. They have replaced the O2 sensor again( again why) didn't fix it. They are now thinking injectors, no CEL for anything however that's what they see on the scanner.
Any idea where to start? I should add this is all under my extended warranty so no charge to me.
Thanks all!

What is the actual P-code it is throwing?

 

[airline tech]

Here is something I posted awhile back

use this for normal readings (compare)

Engine PID Data- Fuel Trims and Related | 2019+ Ford Ranger and Raptor Forum (5th Generation) - Ranger5G.com

The key for diagnostic on the direction to go is:

LTFT at Idle
LTFT at Cruise (2,000) RPM under load or just in park at 2,000 rpms

Does it change?

and did they do a KAM reset? Reason is that the PCM has learned bad data from the O2 sensor issues - A KAM reset will reset the fuel trims to zero, now you have a valid starting point and if the fuel trims still average 13% then dive into the troubleshooting steps.

The key is to watch the following PIDs at Idle & Cruise and note what the Fuel Trims do between the 2 conditions

MAP
O2 Sensor
STFT
LTFT
Fuel Press
Fuel Rail Press

Post the 2 separate conditions and i can give you a direction to go next.

You have stated O2 sensor replacement - Which One? Upstream or Downstream? for the Ranger they both have control on fuel delivery only the downstream is a smaller window than the upstream.

and Vacuum Pump???? I assume you are referring to the brake booster hose (aspirator valve)

IF LTFT is High at Idle only = Unmetered Air
If LTFT is High at Idle & Cruise (2,000 RPMs) - Fuel Delivery or MAP/O2 Sensor bias

I am assuming you are not registering misfires and only have the high LTFT, to me this most likely rules out Injectors.
You can run a Cylinder Balance Test and an Injector Relative Flow Test to get a visual indication on cylinder and injector condition with the scan tool.

 

[Starjammir]

What is the actual P-code it is throwing?

No codes

 

[airline tech]

No codes

LTFT has to be above 20% (range) before it will code

 

[diesel924]

Well he says he is getting a CEL. Now there are no codes? Are there no codes because they were erased?

 

[airline tech]

Well he says he is getting a CEL. Now there are no codes? Are there no codes because they were erased?

Previous issues with 02 Sensor codes - numerous replacements- Wire Harness, fixed that issue.
He has another issue- currently, High LTFt’s and no codes - I do question the reason for the- high labor cost for replacing the Intake Valves - it appears it’s being shot gunned troubleshot without any real data to back it up or we are only getting basic details.
What did the valves look like and why did they not clean - first
The first Red Flag = 8 - O2 sensors replaced and no one checked wiring - it needs to move to another shop , that has better technicians.

 

[diesel924]

Ah, I see that now.

 

[Starjammir]

More work was done
Ford said to replace the fuel injectors. That was done and didn't fix the problem. They have another engineer coming out to look at it this week.
Seems to be problematic!

 

[Starjammir]

As for replacing the valves, it's what Ford, the hotline, said to replace.

 

[diesel924]

Do you have repair orders you could attach?

 

[rang19ca]

This sounds like parts replacement and no real reason other than Ford said do it. Since they seem to be taking care of the cost, let them do it. Let us know what the end result it, i'm curious.

 

[airline tech]

So what is the specific fuel trim readings of STFT and LTFT and MAP between Idle & 2,000 RPMs - I need the LTFT data mainly, and many other PIds to actually see what is off or out of specs , something simple is being overlooked that is not bad enough to code and with the data so far it appears to be on the emission side , but this is why the LTFT is important on what it does at idle and above idle.

 

[Starjammir]

L

Do you have repair orders you could attach?

I have nothing other than phone calls.

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