P1151 - 2000 Ex v8

[Kidd7]

To share some data, Bank1:

Bank2:

This is an extreme example on the bad side, it's usually much more intermittent.

 

[Kidd7]

Somewhat of an update:
- Saturday morning ~70 miles round trip no issue (mostly highway)
- Saturday evening ~45 miles round trip mostly country roads again no issue
- Sunday morning ~ 32 miles one way, mostly highway ran great

That trip was to visit a friends church, she sat in the shade for ~2hrs max. Upon startup to leave she ran rough, along the highway you could feel the lose of power. We needed gas so I pickup up some seafoam and added it to the fill up, just in case I have a sticky injector that is actually dumping too much fuel. Start up at the gas station was bad, started fine, but RPMs up & down, I held the RPMs at ~2k for a little while and upon letting off gas she idled fine. The initial drive home from the gas station was a little rough, this was on city streets now, but smoothed out and shortly into the drive she ran just fine.

The wiring manual referenced above is in route. And I'll be looking over the data collected today.

 

[Kidd7]

Looking at the data from the last drive home there is 0 response from the O2 sensor, whatever it was might have just completely crapped out. That'll at least make it easier to troubleshoot. We'll see tomorrow.

 

[Kidd7]

The EVTM arrived last night. For this particular O2 sensor there are no connectors between it and the ECU. The way I interpret the wiring diagrams the signal output of the O2 goes into the ECU on pin 87; power to the O2 comes out of the ECU on pin 91. Pin 91 powers its actually signal return for all 4 O2s as well as a few other sensors, being that the other sensors are working fine I doubt that's the issue, with 1 minor exception: it is possible that the wire from the junction to the O2 is flakey and not any other connections.

I'm going to test the voltage at the TPS, Intake air Temp and the O2. Instead of power I need to test the return path from these sensors to the ECU.

Also, a point of information. Last night the alternator died, not completely but it wasn't supplying enough power to charge. I replaced the alternator, charged the battery overnight and started her this morning. She ran great, over time a roughness in the idle returned and that same O2 sensor became flakey again. The battery was disconnected from the truck while charging so the ECU had plenty of time to fully drain and clear out any bad data.

 

[Kidd7]

Looking through data collected today, here's what I can surmise so far:
- there is a pattern of very flat switching for all 4 O2s at the same times. Flat meaning the exact same Vp-p.
- It's during this time that the short term fuel trim on bank 2 maxes out.
- BK1 fuel trim is affected by this scenario, but to a much less degree

I am currently unsure what this means and am taking a walk to clear my head, any input is much appreciated. I can also share either screen shots or the excel file with the data.

 

[Turdle]

Thinking aloud I want to see inside the pcm

 

[Kidd7]

I opened up the PCM and didn't see any noticeable defects, the board is conformal coated so that makes inspection challenging.

 

[410Fortune]

Change the 02 sensor?
There is indeed a plug at each sensor

They do wear out

 

[Kidd7]

Change the 02 sensor?
- Same symptoms with 2 different O2 sensors

There is indeed a plug at each sensor
- Yes a plug at the side of the tranny for the O2 to plug into; the wiring for this particular O2 goes straight to the PCM plug, not through any other connectors.

 

[Kidd7]

adding some pictures of the torque graphs; Left side is back 2, right is bank 1. From the top: LTFT; STFT; O2S1.
Initial cold start up:
View attachment 7661

Stopped at the store, B2O2S1 is now switching, but Fuel Trims have only slightly changed:
View attachment 7664

These next 2 are sitting at the next stop after coming out to leave.
Initial start after grabbing coffee, notice B2O2S1 is flatlined, STFT2 is maxed out:
View attachment 7666

While still sitting at the coffee shop, rev'd the engine then this:
View attachment 7667

View attachment 7668

And now once I pulled in the driveway:
View attachment 7669

The misfire count is now 72; not sure if this PID is accurate or not. This data just doesn't make much sense to me anymore.

 

[Kidd7]

I pulled the PCM yesterday and inspected the board more thoroughly, no noticeable defects.
This morning I need to move the Ex in order to get my car out of the driveway, it ran pretty good. The O2 in questions began switching, the Fuel trims were near 0 and very similar bank to bank. Now it didn't run long, but I did let it warm up.

Being that this is after the PCM was out for a while, long enough to reset and clear all data. This kind of leads me to think the PCM is problematic.
I did log some data and plan to look it over later today.

 

[410Fortune]

What about an issue in the fuel system?

1151 is sensor indicates lean
So the pcm will attempt to correct by dumping fuel… when it cannot correct you get a code

Could be low fuel pressure, regulator or vacuum issue, air leaks
Misfires detected usually indicate an issue with an injector

Many 02 sensors same issue
Wiring checks out
PCM no visible issues
Keeps reporting same code

It maybe just lean
On page one anothet truck with this code was solved with a pressure regulator

 

[Kidd7]

I replaced The fuel pump & filter in early Feb; not saying it couldn't start acting up, but....

Could be low fuel pressure, regulator or vacuum issue, air leaks
- wouldn't these cause issues with both banks?
- A stuck injector would be limited to one bank.

On page one another truck with this code was solved with a pressure regulator
- I don't see a fuel pressure regulator listed on rockauto, is there one on the fuel rail or is it on the sending unit in the tank?

This is helping, thank you.

I admittedly may be going down a rabbit hole with the PCM; last week the alternator died, could possibly have been sending dirty power for a while and compromised the PCM. Of course, if this is the case it would be odd to affect only bank2 fueling.

In searching for the thread mentioned above with the regulator fix I found an old thread of mine when I ultimately replaced both front O2s. Strangely the symptoms were the same back then: P0174 v8

In that thread turdle suggested a leaking injector, I wonder if replacing the O2s somehow band aided the symptoms. Now the injector has gotten worse and the symptoms are more prevalent.

It's so frustrating being intermittent like it is; I suppose next step is to use a stethoscope to listen to the injectors to see if one is hanging...

 

[410Fortune]

Check fuel pressure at rail
Listen to injectors
Blurp the throttle and then shut it down. Pull the spark plugs … any wet with fuel?
Check pcv valve, is it seated? Plumbing to it in good shape?
I have seen a leaky egr valve / egr base gasket cause funky readings and misfire on bank one


96-98 return fuel 5.0
Orange injectors
Explorers have two fuel lines to the fuel rail (feed and return) these trucks the pressure regulator is on the fuel rail at engine
These systems run at 36-42 psi

99-01 returnless fuel 5.0
White injectors
Explorers have single fuel line to the fuel rail (feed) these trucks the pressure regulator is in the tank, part of the pump, sender and hanger assembly
(There is a vacuum pulse damper on the fuel rail that many mistake for a regulator)
These systems run at 58-64 psi

The pcm only energizes the fuel pump relay and turns the pump on and off, the pcm has no idea what pressure the system runs at or which rail you have

Resealing the upper intake plenum and injectors is not a terrible job on a 5.0
New quality reman injectors are also not terribly pricey

Hint hint nudge nudge

I find if I have to listen to injectors I mine as well pull them and replace my gaskets, o rings, and possibly injectors… at least bench test the injectors and put them back in after verifying each one is opening and spraying properly. Good chance to Visibly check all wiring and plugs. Inspect all intake vacuum and plumbing, etc rule things out as your possible cause . As a good mechanic we have to rule things out at the cause without spending $$$$

Smoke machine / test can show any gross intake leaks… like around the egr valve

 

[Kidd7]

I have some gaskets & injector "rebuild" parts on order.

I did notice that intake has to come off to get to any of these injectors. Like you said since it's off clean, test & rebuild injectors.

I have a 2000, they are white injectors. 17# correct?

 

[410Fortune]

19#

All 5.0 are 19# per hour fuel delivery rated
Orange are 19lbh at 42 psi
White are 19lbh at 64 psi

Yes upper intake / plenum is removed

You will need big 1-1/4” (I think it’s 1.25) wrench for the egr line
Sometimes the egr line can get stuck and will actually rip so it’s not a bad idea to replace it they are cheap enough

 

[Kidd7]

thanks for the clarification on the injectors, in all my searching I've not seen the flow rate related to pressure. It makes perfect sense.

And just to add: at times when it's running bad burping the throttle seems to level it out, that makes sense with an intermittently sticking injector.

 

[410Fortune]

Smell your oil, any fuel?

If so get that injector and that oil out of there

 

[Kidd7]

Smell your oil, any fuel?

If so get that injector and that oil out of there

No fuel smell on the dipstick.

 

[Kidd7]

I was going to open her up this weekend, but I got sick, then we had a tropical storm roll through and I don't have a garage to work in. Today the weather has cleared up and I'm heading out there shortly to get busy.

The odd/ infuriating/ frustration here, she ran great all weekend. Now looking at the data there was ~1/2 hour of her acting up, but that did not affect drivability like it normally does.

At any rate off to wrench.