P04F0 code - Evap System problem

[quangdog]

The best suggestion I've found so far is to start by understanding the system, then use Forscan to real-time monitor each of the components in the system while driving around trying to get the code to trigger. If you can catch the test as the vehicle runs it, while monitoring each component in Forscan, it should be easy to identify which specific component has failed.

Still - pain in the arse to troubleshoot.

Whelp, I tried this. I reset the CEL on Tuesday, then hooked up a laptop and every time I drove the truck since then I did it with Forscan running and making pretty graphs of what the EVAP system components were doing. I was able to capture the EVAP tests running, but I'm having trouble making good sense of the results. The PIDs I was able to plot don't always make a lot of sense, and everything is pretty cryptic. Also, Forscan is pretty limited with how much it lets you zoom out and read through the results. Here are a few screenshots - First, here's a list of the PIDs I graphed, though this does not:

And here is the Oscilloscope graph of these pids for a drive which detected a problem and turned on the CEL:

Apologies that it's pretty tough to read (click on it to zoom in) - I may try to see if I can get a better capture by hooking up to an external display that offers a higher resolution.

Does anyone have enough experience troubleshooting this sort of thing in Forscan to be able to point me to which component may be my culprit? I mean - I can clearly see the test running, clearly see pressures changing, but I'm not sure which phase of the test caused it to fail, and which pressure reading was out of spec.

I saved all my drive oscilliscope data, and would be happy to share it with anyone who may be interested in troubleshooting further with me.

Thanks!

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[airline tech]

I dug into the manual some, and if you just isolate down to that specific code.
It appears to be a simple repair.

When is test:

Note: Since this code (P04F0)) is not a Leak Code, then this tells me that this Pinpoint Test is not commanding the Evap Canister Vent to (Close)
Note: The Canister Vent is Normally (Open) unless commanded closed for Leak Check Monitor.

So, this code only ties to this specific (Failure)
and
You are only opening the (Purge Valve)
You are monitoring the FTP - Voltage Change (Difference) Between

Purge Valve - Closed (Normal) (FPT - Voltage) = (No Vacuum on the system)
Open - (Commanded Open) = (Vacuum Applied by Intake Vacuum)


From a Evap System Test - with a scan tool
Use this and see if the (In-Test) matches what you see in Forscan

Monitor FTP - PID (Voltage) - Engine Running (Idle - Normal PID Spec = 2.65 Volts) Approx
Command the Evap Purge Valve (Open-100%)
Monitor PTP - PID (Voltage) - Did it Drop Below 1.5 Volts

Yes - Go to Step 1
No - Go to Step 2

Step 1:

Check for restrictions or contamination.
- Canister Vent Valve
- Canister Vent Valve (Filter)
- Evap Canister

Concern - Yes ( Repair as Nessary)
No - (Go to Step 2)

Step 2:

Remove and Check Evap Ejector - (Connections for Blockage at hoses and intake ports)
Concern - Yes - (Repair)
No - (Replace - Ejector)


Now with Ford Service Manuals being typical (Confusing)
If you are using the Pinpoint Test - It tells you to Check and or Replace (Ejector) -- OK ???

Now try to find - Replace in the Manual (WTH) - No location found.
Go to Decryption & Ops (Below)

It mentions what it does, but does tell you, if it is a separate part or integral part of the purge valve (GRR)

So, with a little research, and the pinpoint test not being specific to the Ranger, it covers other models such as the F-150, I find that on the F-150 the Ejector is a separate part, the Ranger includes it (integral) to the Purge Valve

Evaporative Emission (EVAP) Canister Vent Valve

The EVAP canister vent valve (located in the EVAP canister dust box) is part of the enhanced EVAP system controlled by the PCM. During the EVAP leak check monitor, the EVAP canister vent valve seals the EVAP canister from the atmospheric pressure. This allows the EVAP purge valve to achieve the target vacuum in the fuel tank during the EVAP leak check monitor.

Evaporative Emission (EVAP) Check Valve

The EVAP check valve is used on turbocharged engines to prevent boost pressure from forcing open the EVAP purge valve and entering the EVAP system. The valve is open under normal engine vacuum. The valve closes during boost conditions to prevent the fuel tank from being pressurized and hydrocarbons forced out of the EVAP system into the atmosphere through the EVAP canister vent valve. When the engine is OFF, or at atmospheric pressure, the EVAP check valve is in an indeterminate state. The EVAP check valve is an integral part of the EVAP purge valve assembly.

Evaporative Emission (EVAP) Ejector

The EVAP ejector is used on turbocharged engines to create a vacuum in the EVAP purge line from the EVAP purge valve to the intake air system. During boost conditions, boost pressure flows through a venturi inside the EVAP ejector creating a vacuum in the EVAP purge line to the intake air inlet to the turbocharger. When the second EVAP check valve is open, the purge vapor is drawn through the EVAP ejector into the intake air tube, through the turbocharger and charge air cooler, to the intake manifold.

Evaporative Emission (EVAP) Purge Valve

The EVAP purge valve (located near the engine) is part of the enhanced EVAP system controlled by the PCM. This valve controls the flow of vapors (purging) from the EVAP canister to the intake manifold during various engine operating modes. The EVAP purge valve is a normally closed valve. The PCM outputs a duty cycle between 0% and 100% to control the EVAP purge valve.

Evaporative Emission (EVAP) Vapor Blocking Valve

The EVAP vapor blocking valve is a normally open valve, electrically closed by the PCM., to isolate the fuel tank from the rest of the EVAP system. The EVAP vapor blocking valve will automatically open to relieve excess pressure or vacuum, in the fuel tank, if the pressure or vacuum reaches a maximum calibrated value.

Fuel Tank Pressure (FTP) Sensor

The in-tank FTP sensor or the inline FTP sensor measures the fuel tank pressure.

Fuel Vapor Vent Valve (FVVV)

The FVVV is a PCM controlled solenoid that isolates the fuel tank from the rest of the EVAP system. The PCM opens the FVVV during refueling to allow the flow of vapors from the fuel tank to the EVAP canister. The FVVV will automatically open to relieve excess pressure if the fuel tank pressure reaches a maximum mechanical relief threshold value.


My thoughts:

Hopefully, this helps

So, I will say if you only have (P04F0) Code, and no way to properly test without a scan tool.
Then the most likely failed part is the Evap Canister Purge Valve since it incorporates the check valve and ejector
So, if you were to shotgun any parts at it, this would be my first shot.
as the Canister (VENT) is always open (Normally)
If there was any blockage there you would experience issues with fueling the truck.
Pump constantly tripping off when you are not full (yet) - The Check in (Step 1)

This may be a hard part to find, as I cannot locate any part number for it, I only find the Vent Solenoid. Not the Purge Valve.
You may have to get part number off the part itself and then start a search.

 

[quangdog]

HOLY CRAP. I owe you a case of your favorite libations. Or a few pizzas, at least - your choice.

Tomorrow I will start digging for an Evap Canister Purge Valve, and let you know what I find. I've looked through multiple diagrams for this system, and in typical Ford fashion they don't bother putting part numbers on the diagrams. If I'm reading this diagram right, the ECPV hangs off of (or is very near) the intake manifold:

After a brief search, all I can find is 9U5Z9F945C, which is the solenoid you already found that hangs off the EVAP Canister (16 in the diagram above), and is not the right part.

I'll let you know what I find.

THANK YOU!

 

[airline tech]

Here is the location: Note the Oil Fill Location as Ref

Replacement - By the manual has you replace the whole assembly (Tubing Included)

I suspect the reason being that any blockage or leak in the tubing will show the purge valve as failed.

I would check for power at Pin 2 of the connector: If you can see it (Green Wire)
It should have power with key on

The other wire (Broen/White) is the PCM control ground.

Then I would check the valve itself (Ohm) Meter - Between the pins should have continuity.

This valve typically fails open / closed and not electrically.
It is more inside the valve itself; you may be able to spray some (MAF) cleaner inside to free up any debris causing it to stick.

With it being you do not have any Leak codes; I think you have a valve that won't open or clogged or blockage in the tubing between the valve and vapor canister.

This is where a scan tool would be helpful, as when you command the purge valve open you should hear a click at the valve and if you have the tube off the valve coming from the vapor canister - you will have vacuum on the nipple (on the valve)

Just from the diagram, I cannot tell what tubes feed what

 

[quangdog]

Here is the location: Note the Oil Fill Location as Ref

Replacement - By the manual has you replace the whole assembly (Tubing Included)

I suspect the reason being that any blockage or leak in the tubing will show the purge valve as failed.

I would check for power at Pin 2 of the connector: If you can see it (Green Wire)
It should have power with key on

The other wire (Broen/White) is the PCM control ground.

Then I would check the valve itself (Ohm) Meter - Between the pins should have continuity.

This valve typically fails open / closed and not electrically.
It is more inside the valve itself; you may be able to spray some (MAF) cleaner inside to free up any debris causing it to stick.

With it being you do not have any Leak codes; I think you have a valve that won't open or clogged or blockage in the tubing between the valve and vapor canister.

This is where a scan tool would be helpful, as when you command the purge valve open you should hear a click at the valve and if you have the tube off the valve coming from the vapor canister - you will have vacuum on the nipple (on the valve)

Just from the diagram, I cannot tell what tubes feed what

Thank you again! I'm serious - you PM me where to send it, and a case of whatever you like to drink is on the way to you.

Is that part number KB3Z9D289B? Sure looks like it from what I've found online. I'm planning to go inspect things on the truck later this afternoon.

 

[airline tech]

Yes, KB3Z9D289B is the correct part number

That Helps
The tube on the back - beside the elect connector is the feed from the Vapor Canister

The Front Left - I think is the Check Valve
The Front Right - I think is the Ejector

Whichever one runs to the Turbo will be the Ejector

Hard to tell for sure but may be reversed.

 

[quangdog]

Yes, KB3Z9D289B is the correct part number

That Helps
The tube on the back - beside the elect connector is the feed from the Vapor Canister

The Front Left - I think is the Check Valve
The Front Right - I think is the Ejector

Whichever one runs to the Turbo will be the Ejector

Hard to tell for sure but may be reversed.

Whelp, this is a bit embarrassing. When a CEL light comes on, I've been so conditioned to just pull out the code scanner and start researching the codes I find, that I had not bothered actually opening my hood until today:



Since this video, I did reset the check engine codes, and went for about an hour long drive while monitoring the EVAP system PIDs again. The code has not returned, though to be fair, I did not happen to see any EVAP testing actually happen during this specific drive. I'll continue to monitor it for the next week or so, and if the code comes back I'll go ahead and replace this hose harness - it's entirely likely that debris has been able to work its way through that hose up to the purge valve itself, so the valve may still in fact be bad.

I'll come back with any updates if the CEL comes back, etc.

Thank you again!

 

[airline tech]

Good Find, I would say that was it

 

[quangdog]

Good Find, I would say that was it

I just wanted to circle back to this thread to report that the check engine light has not returned since reconnecting that hose.

i’m keeping my fingers crossed that the root cause of the problem has been found and fixed.

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