What in the world is going on with this Explorer - Popping, Weird Idle, and now RSC

[PotatoExplorer]

Hi Explorer folks -

I'm having a problem with this 4th gen Explorer (2008 Limited, 4.6L V8, 4x4). I've cross-posted this on a few other Explorer Facebook pages but with no luck on the diagnosis. I drove around yesterday evening and recently got done with a several hundred-mile trip last week with no major problems. Left the grocery store last night after driving around to a few other places and kept hearing a subtle "popping" noise that at first, I thought was my 9 month old son letting out a really long, slow fart (it wasn't). I can only hear it from the rear end of the interior of the cabin near the factory sub and only seemed to happen while stopped/idling. When the "pops" happened it seemed to also idle roughly with visible rpm changes. I WOT 2 times and could get the "pops" to happen while driving and it actually chirped the tires and lunged a bit midway through during the 2nd short WOT. Any ideas? I'm guessing maybe a fuel pump? It just happened completely out of the blue which is strange... After pulling into the driveway after the 2 WOT, I sat with my foot on the brake. Felt like a lunge or big clank of some sort every 3-15 seconds. Thanks for any input guys.

I don't believe it's from the sub or some sort of interference with the sub. I placed my ear on the speaker grille and the "popping" isn't coming from the cone.
I don't believe it's the rear blend door actuator. I believe if it was a blend door actuator, the sound would be more rhythmic and the sound is definitely louder on the passenger side vs the drivers side rear cargo area. I'm fairly positive the rear blend door actuator is located on the driver side.
I know there's a fuel pump relay module in that back rear location. Not sure if that could give off such a loud sound like this.

I took this video this morning so you all could hear the "popping" sounds. This morning I did get a wrench light that wasn't there last night but didn't have any time to check the codes. Right after turning off this video I got a "SERVICE RSC NOW" warning with that annoying warning chime. I don't know if this could be related or now I have 2 unrelated problems that just popped up together.

 

[ThunderbirdSport]

plugs? coils? test fuel pressure?

Get you a good code reader (not the 20 dollar **** from wally) and see what that tells, as well

(all the cheapo code readers are good for is clearing the codes...they don't really go into any good detail as to WHAT the code is, or from, so much..have an oreilly nearby? they will usually let you pull code(s) in the parking lot for free..bonus..their readers can also scan the PCM for trans codes as well.)

 

[PotatoExplorer]

plugs? coils? test fuel pressure?

Get you a good code reader (not the 20 dollar **** from wally) and see what that tells, as well

(all the cheapo code readers are good for is clearing the codes...they don't really go into any good detail as to WHAT the code is, or from, so much..have an oreilly nearby? they will usually let you pull code(s) in the parking lot for free..bonus..their readers can also scan the PCM for trans codes as well.)

I hope it's not the coils or plugs - Replaced all coils and plugs a little under 25k miles ago (maybe 3-4 years ago). Don't have a fuel pressure tool although I hear they are pretty cheap.
Unfortunately I don't have any orilleys near me. I do have Forscan on my laptop at home. Hoping to be able to hook that up on my lunch break and see what it says.

 

[Explorer_PL]

Forscan should pull all codes. 25k on coils/4 years - I would not rule those out but I never had popping like that when coils or plugs went bad.

 

[PotatoExplorer]

Well, I checked a few things over lunch. Here are a few more observations -

1) The fuel tank pressure went from 17-40 (no idea what the unit is...kpa?).
2) Towards the end it was registering 417 misfires. I'm just now realizing I didn't look for a specific cylinder misfires... or can I even do this? It was saying it was misfiring around 2,100 RPM
3) I could hear the main engine fan cycling for a few seconds on and then a few seconds off. It's never done this before.
4) When I placed it in reverse it would "clunk" really bad. It would do this anytime I would take it out of reverse and back into reverse.

5) I registered these DTC codes for the following:
TCM - None
PCM - U0101-FF
OBDII - U0101-C
APIM - None
OCS - None
4x4M - U1900-2F
ABS - U1900-20
ABS - C1285-20
ABS - B1342-20
RCM - None
IC - B2097-20
IC - U2013-20
IC - U1900-20


6) Looked over all the fluid levels, electrical connections and hoses, all looked good. Quickly popped my head under and checked tone rings in the rear for the RSC issue and visually they looked good.

20200925_125228

20200925_124104
DTC

20200925_125210
Fuel Tank Pressure is the 2nd from the top readout

20200925_123029
Another video


This is like the 5th time using Forscan, so apologies if it looks like I have no idea what I'm doing... because I really have no idea what I'm doing.

 

[Explorer_PL]

If you had the ELM 327 adapter with fast or slow speed switch, you could access mode 6 where it lists every cylinder individually with misfires:

https://rover.ebay.com/rover/1/711-...0001&campid=5574912417&icep_item=143604168387

I believe the normal fuel pressure is 38-40 PSI
When you switch from D to R and it clunks, I am thinking about torque converter or tranny.

 

[PotatoExplorer]

If you had the ELM 327 adapter with fast or slow speed switch, you could access mode 6 where it lists every cylinder individually with misfires:

ELM327 USB 25K80 CH340T OBD2 Diagnostic Cable With Switch for FoCCCus FORScan US | eBay

I believe the normal fuel pressure is 38-40 PSI
When you switch from D to R and it clunks, I am thinking about torque converter or tranny.

Yeah, same ELM 327 adapter I have. I just finished watching a video by Ford Tech Makuloco about the COPs causing interference and causing transmission issues (which several others on this forum have found out and also why I changed mine because of that weird RPM shudder issue several years back) -



I have the U0101 codes... wondering if the COPs are jacking up the transmission and also messing up the ABS. I was in the engine bay not too long ago vacuuming out all the caked up leaves in the plastic cowel. May have jostled some wires but I did just check all those connections on my lunch break and found nothing.

I'm also just waiting for my torque converter to die on my any day... but I've been waiting for close to 5 years now. Looks like I've got more work to do with no time to do it. Already have it scheduled to go into my local mechanic on Monday.

 

[Explorer_PL]

Mine died at 200k

Why did I pull my engine out twice in a month - long story.

Why I pulled my engine out twice in a month - long story. Ok boys and girls. Get ready for a long reading  Somewhere in January at 199 k miles, my engine developed a nasty knock and valve train noise especially at lower rpm, and when stopped at a red light or in traffic. I went to one shop...

www.explorerforum.com

But U1900 and U0101 were caused by coil #4 when I had this problem, since the harness runs close to it and it was causing interference with the signal. There is my post on that somewhere here.

 

[PotatoExplorer]

Mine died at 200k

Why did I pull my engine out twice in a month - long story.

Why I pulled my engine out twice in a month - long story. Ok boys and girls. Get ready for a long reading  Somewhere in January at 199 k miles, my engine developed a nasty knock and valve train noise especially at lower rpm, and when stopped at a red light or in traffic. I went to one shop...

www.explorerforum.com

But U1900 and U0101 were caused by coil #4 when I had this problem, since the harness runs close to it and it was causing interference with the signal. There is my post on that somewhere here.

Oh, I'm very aware of your situation Mr. Explorer_PL. I've read your thread countless times trying to kill my RPM shudder problem. I'm probably going to read it again just for the fun again

I think I might have a few of my old COPs in my garage. I might literally try throwing a new one on #4 since it should only take a minute to do and see what happens. I've got nothing else to lose.

 

[WaltZ]

Its not the fuel pump. When that goes, there's no warning.

Bad coils on cyl 2,4,6, and/or 8 will mess with the electric signals going to the PCM. I changed out my coils 2 years ago for cheap $75 Chinese coils. I'm back to the jet engine sound because the tranny is getting bad signals and now I hear a whistle sound in the speakers when I press the gas and goes away when I let up. Rock Auto just delivered my Motorcrafts yesterday and they're getting installed Sunday.

The Drive -> Reverse clunk in the rear is now back after replacing my differential a few years back with an eBay used diff. I can live with that.

 

[Explorer_PL]

Thanks WaltZ

I thought because of harness position, #3 and 4 are the closest to it, 6 and 8 are on the other side.
For some reason, #8 goes bad most often

 

[WaltZ]

It's the passenger side coils. I have my numbers reversed

 

[zerodevil]

As others have said, ford ran the wiring harness over the top of 3 of 4 of the Ignition coils on the passenger side of the vehicle. Failing, and cheap coils can throw tons of EMF out, and induce voltage onto the wires ran directly over top of them quite easily. It doesn't take much to mess with sensors reading 1-12 volts for info. Failing coils in these areas can cause TONS of random behaviors because these wires are essentially everything the PCM controls.

I'd wager money you can swap coils from driver to pass side and see if your error goes away, if it does, get some motorcraft coils and call her a day

 

[D Hook]

Oh, I'm very aware of your situation Mr. Explorer_PL. I've read your thread countless times trying to kill my RPM shudder problem. I'm probably going to read it again just for the fun again

I think I might have a few of my old COPs in my garage. I might literally try throwing a new one on #4 since it should only take a minute to do and see what happens. I've got nothing else to lose.

Are you using Motorcraft coils?

 

[PotatoExplorer]

WELL WELL WELL! Good news - Problem solved. It ended up being COP on cylinder #4. As others said, I think it was throwing electrical interference into the communication from the TCM to PCM causing the transmission pressures to be all jacked up. I think that's the reason for the huge clunking into reverse. I'm completely guessing here but I think the "popping" sounds may have actually been from the subwoofer (even though I put my head right up to the speaker grille and I'm still fairly certain it was coming more towards the liftgate vs the 2nd row seats), which may have also been receiving some electrical interference. The "popping" was a bit erratic but now in hindsight it was following a similar pattern to every time that cylinder fired. This was causing the rough idle and I assume triggering the "SERVICE RSC NOW" issue.

I swapped out COP #4 with an old Motorcraft COP I had on cylinder #1 when I replaced them all several years ago. As soon as I fired her up, no popping noises, no rough idle, no major clunking shifting into reverse and drive. Took her for a 20 minute test drive pushing her pretty hard. Pulled over a few times to turn off/on and no issues.

I had highly doubted it was the COPs since I serviced them not too long ago with genuine Motorcraft replacements but I guess parts break down... probably more so with COPs on cylinder #4 and #8.

Thanks everyone for the input and helping me tackle this. Now I got to call the shop to cancel my appointment. Probably just saved me an ass ton of money and time. Thank you!

 

[D Hook]

Good job!

 

[Explorer_PL]

Yep, coils .....
you did better than me.

I replaced 2 mechatronic assemblies because of the bad coils. Back few years ago, somehow this was not a common knowledge what a havoc bad coils can create.
Opening the tranny and removing the valve body was not exactly something I do every day, so being an amateur DYI, I was praying that the car starts and actually drives.

It did but It was still kicking and trowing 0101 and 1900.
Then I cam across an article about that harness interference with bad coils, my post is somewhere here also.
Motorcraft coils replaced some aftermarket ones and the errors never came back.