Explorer Sport - Random misfire P0300 and P0316

[FutureRider]

Hey folks, you all have been a great help over last few years. Time for my first question/post...

2015 Explorer Sport with ~56K miles. Back at the 53K mark injector #2 stuck open; P302 misfire, P0087 and P00C6 fuel rail pressure low, flashing MIL, etc. Drove about 2 mi to safety (and my go-to repair shop). Injector was replaced and all's been fine for several thousand miles until a couple weeks ago when it started hesitating, loss of power, etc., then threw a P300 random misfire and, later, P0316 misfire at startup. Cleared the codes and cycled through a couple of fill-ups since then, in case it was bad gas, and it has repeated intermittently. I know the injector failure can cause downstream issues with the O2 sensors and Cats, but the run time was minimal in that condition. Anyway, it's acting up again now (P0300 and P0316) and I'm debating taking it in tomorrow to see what they come up with. If not for Thanksgiving week and 3 kids running around, I might try some things myself.

I'm using an OBDLink MX+ and have the current codes (as above) and the freeze frame data. One weird thing I noticed while watching the O2 sensors as the engine is running: Bank 2 sensor 1 voltage seems normal (0.2 to 0.9V) but the Bank 1 sensor 1 is steady at 0.0V. I could be looking at the wrong data, but could it have been damaged by the high fuel flow during the injector failure and finally gave up the ghost? I'll add that I chose not to have the shop change the plugs while they were in there for the injector; seemed a little premature at the time, but maybe a bad call? Whatever it is is random and somewhat intermittent.

I know there's a laundry list of parts and procedures that can be associated with these codes, so thanks in advance for any thoughts or ideas.

 

[peterk9]

Welcome to the Forum.
Hopefully, someone will have some ideas. It does seem a little early for plugs.
FYI, Misfire codes on 5 Star tune

Peter

 

[FutureRider]

Update: Took it to my go-to shop, where it's been since the day before Thanksgiving and they are, in a word, stumped. They've tried a lot of things and say this is one for the books; not plugs, not coils, not O2 sensors, not EGR valve, not injectors, not hi-pressure fuel pump, not fuel, not cats.

What started as an intermittent problem has been getting more consistent and somewhat worse, now with a couple additional specific cylinder misfire codes on both banks (but nothing else). They have a specialty diagnostic guy coming in Tuesday, and if he can't figure it out it's off to a local dealership for a Wednesday morning appointment and a service manager who coincidentally used to work at the place where the truck is now. I would have taken in there first if the powertrain warranty wasn't expired (years only, still under 60K miles!).

All in all makes me glad I didn't start trying stuff myself, I guess. I'll be sure to let you all know how it turns out in case it can help anyone else.

-- Matt

 

[mguy13sport]

Sounds like a faulty fuel pump maybe. Possibly a faulty high pressure pump? Does it ever stabilize if you just leave it idling? does it want to shutoff if given a lot of throttle?

The HPFP is located on the front valve cover. It's pretty loud if you pull the rubber cover off it. You should hear that thing ticking like crazy if its running properly. Very easy to replace if it is bad. The low pressure pump is located inside the gas tank so much different ball game.

With the OBDLink MX+ and ForScan or Torque, you can monitor the fuel rail pressure via PID sensor. At idle it should be at least 200+ psi. If you add your vehicle profile to Torque, it will auto import the available Ford PIDs (prefixed with [FORD]) for you

 

[FutureRider]

Sounds like a faulty fuel pump maybe. Possibly a faulty high pressure pump? Does it ever stabilize if you just leave it idling? does it want to shutoff if given a lot of throttle?

The HPFP is located on the front valve cover. It's pretty loud if you pull the rubber cover off it. You should hear that thing ticking like crazy if its running properly. Very easy to replace if it is bad. The low pressure pump is located inside the gas tank so much different ball game.

With the OBDLink MX+ and ForScan or Torque, you can monitor the fuel rail pressure via PID sensor. At idle it should be at least 200+ psi. If you add your vehicle profile to Torque, it will auto import the available Ford PIDs (prefixed with [FORD]) for you

Final update:

First, belated thanks for the reply, mguy13sport! The HPFP did play a part in the end.

My shop narrowed things down to a failed cat, which lo and behold was still under the 8/80 emissions warranty. The vehicle was flatbedded to the dealer in early December, where it was discovered that the cat had come apart and taken out the rest of the exhaust system. All still under warranty, but when the new system arrived, just before Christmas, it was damaged... and on nationwide backorder. So the waiting began. Thankfully the dealer provided me with a free loaner, a 2021 Explorer XLT, which was fantastic to have despite my 8-year-old daughter accurately noting that it was "really underpowered."

Unfortunately, the story doesn't end there. After the exhaust system was replaced, the misfiring continued and, in fact, got worse, becoming completely undrivable with injector flow worse the further down the fuel rail you went (2 at full blast, 2 not so much, 2 not at all). Apparently the HPFP was coming apart and sending bits of itself downstream, requiring replacement of the entire HP system. This situation was, of course, NOT under warranty, but I got the vehicle back last week after 3.5 months and it runs like a beast again. I'm sure looking forward to going back to just routine maintenance and tires.

 

[3RVRSSteve]

Greetings all,
I haven't searched too hard here yet but I found one thread with the same codes and no posted resolution. In the stock Explorer forum there's another thread where the OP said the HPFP was the issue behind both these codes.
I've a BDX hand held that won't log so I have limited info to work with. I replaced the plugs with Autolites gapped at .029 and cleaned both map sensors. I've put 93 in the tank and added Royal purple +3 Octane booster. I've cleaned both MAP sensors. I actually noticed improvements in drivability after cleaning the one on the upper intake but the surging and stumbling remain. Plugs and octane booster helped a lot initially because when I first drove it after the tune it was horribly bad.
Driving the car, light to mid throttle it's surging and missing. Feels like it's ready to go great then cuts and stumbles.
80k on this 2019 Sport. No catch can but I do have one. I haven't installed it yet.
I'm looking for advice on what to do first. Tempted to replace the HPFP but $400 just to see if it fixes the issue doesn't seem wise.
TIA

 

[peterk9]

Welcome to the Forum Steve.
Your post was moved to this thread on the same codes.
You mentioned that you have a 5 Star 93 tune but I don't know if that has a bearing on the codes.

Peter