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Discussion Starter · #1 ·
-2014 ST3 with FMIC, exhaust, stratified tune, 68,00 miles

-I began to experience misfires near the top of the Rev range, about 40 misfires per pull. These became became very frequent one week ago and threw codes P0088, fuel pressure too high, and P0300, random misfire. No Negative correction or knock was observed on Cobb AP.

-I then replaced spark plugs because I had some new ones sitting around (one step colder, .026 gap) and flashed back to stock tune for safety, misfires remained.

-I now also have P025A- Fuel pump module A control circuit open, and U0109, lost communication with fuel pump control module A

- I'm not driving the car and have ordered a new fuel pressure sensor, I'm hoping that's the issue.

-I attached screenclips of my data log of a small pull, you'll notice huge discrepancies between the actual fuel pressure and the desired just before misfires occur.

datalog screenclip 1.PNG


datalog screenclip 2.PNG


If the sensor doesn't fix the issue, where should I look next? My guess would be high pressure fuel pump, low pressure fuel pump, or possibly injectors? I took it to a shop and a ford dealer and they both suggested to change spark plugs and did not give much concern to the fuel codes, no help at all unfortunately.

Any advice would be greatly appreciated! I'm really concerned, the car has been perfect for 2 years now and I hope this isn't indicative of future issues.

Lastly, would this have anything to do with the fuel purge valve recall? I got the first recall for it done, but I got another recall for it in December stating that they didn't install the correct software the first time around, thanks ford. I have yet to take it in for the second time.

Thanks for your help!
 

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U codes are communication error codes. The one you're having is regarding the low pressure fuel pump model.

Broken or damaged wiring, & Blown fuses are common reasons that a module will not communicate on the CAN BUS.

The module is located near the rear passenger side of the vehicle.

Either the wiring is damaged or corroded, the power is disrupted to the module or your low pressure pump has failed.

I'd start with inspecting the wiring, fuse, & module first.
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Discussion Starter · #3 ·
Thanks for the reply!

I've been looking around to find the best way to access the LPFP module but I can't seem to find an exact location, do you know the best way to go about locating it?
 

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Discussion Starter · #5 ·
Thanks again!

Unfortunately work is extremely busy for me right now and I don't have the time to thoroughly investigate this issue any further, so I'm taking it to a ford master mechanic who specializes in the focus platform. Is there anything you would recommend me to say/do to help make this process go as smoothly as possible?

My plan is this:

Uninstall the Cobb AP from my ST
Place a document in the car when I drop it off that lists the symptoms, CEL's, and fixes I've already tried, the datalog excel numbers from my "scanner", and state that I'm guessing it's an electrical issue, not necessarily a HPFP or LPFP issue.

My concern is that the mechanic "shotguns" parts at it, but that's a risk I have to take when life happens like this. Hopefully that document would help put him on the right track, or maybe he'll just throw it in the trash.

Would you have any other recommendations before I drop it off tonight?
 

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If he's a certified ford master mechanic then he shouldn't be shotgunning parts.
The codes and symptoms should speak for themselves.
 

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If he's a certified ford master mechanic then he shouldn't be shotgunning parts.
The flat rate pay system makes reasonable people do unreasonable things.
 

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Discussion Starter · #8 ·
If he's a certified ford master mechanic then he shouldn't be shotgunning parts.
The codes and symptoms should speak for themselves.
I was told that a faulty sensor caused metal shavings to be released in the fuel system from the HPFP running too hard. The repair bill is 3000 dollars and the mechanic also stated that my accessport "masked the issue" and caused it to get this severe...... In your experience, could this be true? I understand the risks of running a tune but stratified has a great record of reliability.
 

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Just so I'm clear.
A faulty sensor (unspecified) failed or induced a failure of the HPFP (high pressure fuel pump) which resulted in internal mechanical damage ultimately releasing foreign particles (metal shavings) into the system after the pump?

I'm not here to prove or disprove any diagnosis or worked performed however I will do my best to explain some things.

A fuel sensor in this case a pressure sensor is a potentiometer. It receives a VREF (5 VDC) signal from the PCM. A SIGRTN (clean ground), and a the output from the sensor back to the PCM with the information from the sensor (0 - 5 VDC).

You have two fuel pressure sensors. A high pressure which is located on the rail and a low pressure located between the engine and the driver side firewall.

You can only have 3 errors. No response (dead sensor), sensor high (reading above the expected threshold), and low (reading below the expected threshold). All will generate a DTC, no expectations.

The HPFP is controlled by the PCM through a process know as PWM (pulse width modulation). The PCM can rapidly switch the pumps output on and off to meet the desired target pressure. This is referred to a the pumps Duty Cycle. The HPFP is mechanically driven off lobes connected to the end of the exhaust camshaft.

The LPFP is mounted directly inside the fuel tank. It too is PWM controlled to meet demand.

The Accessport reports information generated by the vehicles system. Period.
Yes a tuner can manipulate data to perform a certain way but if any the Accessport relays too much information to the end user. Search around and you will also hear the AP referred to as a Anxiety Port. It would not "mask" anything.

If you were constantly running the high pressure system at maximum all the time then I could see a potential for damage, but it's a mechanical device and everything fails eventually. (Ask either of my wives or any joint on my body)

Without a detailed description of work and parts I really can't comment much further. However that being said the work and parts better include but not limited to:
Replacement of all injectors, sensor, rail, HPFP and a full fuel system flush.

It's an easy out to take whenever you are aware that a tuner is involved. Snap judgments and or previous experience tends to lead many down this path.

Personally I believe your tune is fine.
But what the hell do I know? I'm just a burnt-out old cop LOL!

J
 
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