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5.4 l 2v P071 & P0174 high lean long term fuel trims bank 1 & 2, Low power under load

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5.4 l 2v P071 & P0174 high lean long term fuel trims bank 1 & 2, Low power under load

 
  #16  
Old 07-11-2019, 11:45 PM
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Originally Posted by R&T Babich View Post
Have you checked out the fuel pump relay?
If the relay contacts are badly pitted the power the pump receives can be be reduced.
I have not checked the fuel pump relay. That' probably the easiest thing to check. Thanks for pointing that out.
 
  #17  
Old 07-11-2019, 11:50 PM
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Originally Posted by JWA View Post
Much like an SMB or adventure vehicle I have too much built in over top of that area. Even so I'd never cut the floor away like that---it opens that area up to rust being formed and spreading rapidly.

When my fuel pump failed I paid for the new Motorcraft part, new fuel filter and two new OEM tank straps. As luck would have it one of the straps had worn a small hole that was relatively easy to fix. Had I not done this no telling how long the undetected leak would have remained plugged by the tank strap insulators.

Yeah dropping the tank is not the cheapest way to go but I think its the best route for higher reliability.

Motorcraft fuel pumps can be found on eBay for just about $100 or more less than I paid at the dealer. I didn't have the luxury of waiting time so had to spring a full $430---Ouch!
JWA, fortunately for me, I live in California. My van is 1998. The motor will burn out long before the van rusts out. Even if this was a new van, I would cut a hole in it. However, I cannot even think of cutting a hole in the roof! I see so many camping vans with vents on the roof. Cutting through the roof means leaks are going to find there were inside the van.
 
  #18  
Old 07-12-2019, 05:20 AM
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Originally Posted by coolfeet View Post
JWA, fortunately for me, I live in California. My van is 1998. The motor will burn out long before the van rusts out. Even if this was a new van, I would cut a hole in it. However, I cannot even think of cutting a hole in the roof! I see so many camping vans with vents on the roof. Cutting through the roof means leaks are going to find there were inside the van.
Fair 'nuff---I keep forgetting you live in the land of no rust!
 
  #19  
Old 07-12-2019, 04:39 PM
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I tested the 4 electrical connections coming out of the MAF with a digital voltmeter and everything is working. I used the following procedure found online at Easy Auto Diagnostics

These are the test steps:


  • Put the multimeter in VOLTS DC mode
  • With the RED multimeter test lead and an appropriate tool, probe the MAF sensor connector's circuit labeled with the number 4, as shown in the photo.
  • With the BLACK lead of the multimeter probe battery (-) negative terminal.
  • Turn Key On with the engine Off You should see 12 Volts on the multimeter. Do you have 12 volts? 12 volts.

In the previous test we checked and confirmed that the mass air flow (MAF) sensor is receiving 12 Volts.

Now we'll check that the MAF sensor is getting a good ground. This Ground is a chassis Ground.

These are the test steps:

1, Turn the key to the OFF Position and put the multimeter in VOLTS DC mode.

2, With the BLACK multimeter test lead and a wire-piercing-probe, probe the MAF sensor connector's circuit identified with the number 3, as shown in the photo.

3. Connect red lead to the battery (+) positive terminal. You should see a voltage of 12 Volts. Do you have that? 12 volts.
Now, we'll check the second Ground Circuit of the MAF sensor (this is known as the MAF RTN circuit).

This ground is provided by the PCM (Powertrain Control Module=Fuel Injection Computer) internally.

Be careful and take extreme care not to short-circuit this wire to Ground or power as you're probing it.

Alright, here are the test steps:

1. Turn key to the OFF Position and place the multimeter in VOLTS DC mode.

2. Probe the MAF sensor connector's circuit identified with the number 2 as shown in the photo with the BLACK multimeter test lead and a wire-piercing-probe.

3. Connect RED lead to the battery (+) positive terminal.

4. Turn the ignition switch to the RUN position. You should see a voltage of 12 Volts. Do you have that? 12 Volts.

Now that the basics have been checked, we'll check the MAF signal coming out of the sensor and going to the ECM.

Start the engine and let it reach it's normal operating temperature. You'll be using the voltage reading you will obtain at idle as a base to diagnose the MAF sensor.

The MAF sensor on your Ford (Mercury or Lincoln) must be connected to its connector to perform this test.
  • With the key in the OFF position probe the number 1 circuit of the MAF sensor connector shown in the photo with a suitable tool connected to the RED multimeter lead.
  • Put the multimeter in VOLTS DC mode and connect the BLACK lead to the battery (-) negative terminal.
  • Start the already warmed up engine and let it run.
  • Note the Volts reading on your multimeter at idle (should be about .9 to 1 Volt DC). This reading may be stable (with only small fluctuations) or unstable with very extreme fluctuations. No matter what the instability in the reading, this will be your base reading.
  • Accelerate the engine (by manually opening the throttle) as you watch the multimeter's voltage readings.
  • At about 1500 RPM you'll see about 1.4 Volts DC. Yes
  • At around 2500 RPM the multimeter should register around 1.8 Volts DC. Yes
  • The actual voltage reading on your multimeter may/will vary slightly.
  • The voltage numbers should correspond to the amount of acceleration.
  • When you release the throttle and the engine returns to idle, the voltage reading should go down and hover around the reading that your multimeter registered in step 6 (about .9 to 1 Volt DC).
  • Repeat this as often as you need to verify that the voltage numbers on the multimeter rise smoothly every single time.
  • If the MAF sensor is good these readings will not spike up and down crazily but will correspond to the amount of air the engine is breathing at the different RPMs you're accelerating the engine to.
  • Did the signal rise smoothly with each increase in engine acceleration and stay steady at idle? Yes
 
  #20  
Old 07-12-2019, 04:46 PM
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Originally Posted by JWA View Post

HC4 CHECK FUEL PRESSURE

[img]VY2~us~en~file=ani_caut.gif~gen~ref.gif WARNING: BEFORE SERVICING OR REPLACING ANY COMPONENTS IN THE FUEL SYSTEM, REDUCE THE POSSIBILITY OF INJURY OR FIRE BY FOLLOWING DIRECTIONS IN FUEL SYSTEM CAUTION, HANDLING AND WARNING AT THE BEGINNING OF THIS PINPOINT TEST.
  • Install fuel pressure tester.
  • Release fuel pressure.
  • Key on, engine off.
  • Access Output Test Mode and run the fuel pump to obtain maximum fuel pressure. (GO to Pinpoint Test HC to refer to the Fuel Delivery System Test Information/Specification Chart.)Note: The fuel pump will only operate for approximately 8 seconds when Output Test Mode is selected and activated.
Is the fuel pressure within the specified pressure range as stated in the Fuel Delivery System Test Information/ Specification Chart?
YesNo
How do I access Output Test Mode?
 
  #21  
Old 07-12-2019, 05:02 PM
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Originally Posted by R&T Babich View Post
Have you checked out the fuel pump relay?
If the relay contacts are badly pitted the power the pump receives can be reduced.
I pulled the relay and the contacts look good. All roads are leading to the fuel pump.
 
  #22  
Old 07-12-2019, 08:40 PM
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Originally Posted by coolfeet View Post
I pulled the relay and the contacts look good. All roads are leading to the fuel pump.
Did you open the relay case to inspect the relay contacts or just looked at the relay connector tabs that plug into the CJB?
I didn't think the casings were removable.
When the relay contacts are pitted the power the pump gets may be reduced causing the pump to run hot and fail prematurely.
I usually see 13.2-13.4v at the Inertia Switch with the engine/fuel pump running.
 
  #23  
Old 07-13-2019, 04:56 AM
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Originally Posted by R&T Babich View Post
Did you open the relay case to inspect the relay contacts or just looked at the relay connector tabs that plug into the CJB?
I didn't think the casings were removable.
When the relay contacts are pitted the power the pump gets may be reduced causing the pump to run hot and fail prematurely.
I usually see 13.2-13.4v at the Inertia Switch with the engine/fuel pump running.
The cases are removable but that's not their design---I've accidentally pulled the cases off the relay base trying to extract one from the under hood relay/fuse box or CJB, even using the fancy relay pulling pliers. Most times the cases will snap back into place without any long term issue.

Just a question but shouldn't the read voltage at the inertia switch or even at the under body connector be closer to the alternator output with engine running? If we're seeing about 14.3 VDC that's not a huge loss but to my mind it should be a bit higher.

And yes a hotter running fuel pump can be early death---another way to somewhat keep that at bay is never running the tank below 1/4 full---it keeps the pump bathed in fuel helping keep it a bit cooler.
 
  #24  
Old 07-13-2019, 07:04 AM
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Originally Posted by JWA View Post
.... Just a question but shouldn't the read voltage at the inertia switch or even at the under body connector be closer to the alternator output with engine running? If we're seeing about 14.3 VDC that's not a huge loss but to my mind it should be a bit higher. ....
Yes, the voltage should be reading about what the alternator is outputting.
14.3v is "high charge" and can be seen for a short time right after starting the engine.
Our Exped and Excur usually are running at 13.2-13.6v .
 
  #25  
Old 07-13-2019, 10:10 AM
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I did not pull the case off. I will attempt to gently pull the case off and take a photo of it in order for someone to point out the inertia switch.
 
  #26  
Old 07-13-2019, 11:46 AM
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Originally Posted by coolfeet View Post
I did not pull the case off. I will attempt to gently pull the case off and take a photo of it in order for someone to point out the inertia switch.
The Inertia Switch is probably behind the passenger right side kick panel, not sure where it is in a van.
Your year van probably has an easy to replace fuel pump relay in a breaker panel with other relays, probably in the engine compartment.
You could try swapping the fuel pump relay with another one in the breaker panel for testing.
 
  #27  
Old 07-13-2019, 03:14 PM
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Originally Posted by R&T Babich View Post
The Inertia Switch is probably behind the passenger right side kick panel, not sure where it is in a van.
Your year van probably has an easy to replace fuel pump relay in a breaker panel with other relays, probably in the engine compartment.
You could try swapping the fuel pump relay with another one in the breaker panel for testing.
I swapped the relay with one nearby and no change in the long term fuel trim.

I have an SCT Tuner. During our month long camping trip, I set the PCM back to "stock". The SCT tuner has 3 options-return to stock, 5.4 Eseries van, and 87 Tow. I will call 5 Star Tunes and ask for clarification. I ran the tow tune a few times on the camping trip and prefer how the van drives without the tune on the freeway.

This afternoon, I set the SCT tuner for 5.4 Eseries Van option which I believe has the most updated files for the PCM. Long term fuel trims on both banks came down to almost 0 while driving around town. I drove over a long grade 2 times and noticed the long term fuel trims going up as high as 22%, but never hitting 25%. I will take the van on a long run tomorrow.

I cleared all the DTCs and no pending or permanent codes were present.

While this is an improvement, I am not familiar with the 5.4 engine and do not know what long term fuel trims should be driving up a long steep grade.
 
  #28  
Old 07-15-2019, 04:54 AM
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Someone will or should correct me but LTFT's shouldn't be significantly affected pulling a grade, the STFT's might swing higher to show more fuel is being added to produce more power under throttle.

The LTFT's would be affected if the PCM sees an increase in unmetered air that isn't passed though the MAF.
 
  #29  
Old Yesterday, 12:17 PM
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Long Term ,will learn lean condition over time, A quick current draw and oscillation check with a scope pattern can tell you a lot with out getting the fuel all over the place.
LT ST is like the old GM block learn and integrator

you can do the current draw at the inertia switch,
voltage drop the ground toojust to be sure
 
  #30  
Old Today, 10:29 AM
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I am checking volumetric efficiency on the MAF. I took the van for a test ride last night and had OBD Fusion turned for data collection. Somehow, I did not save the data. Need to try again tonight.
 

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