I think you may have nailed it right here. And unplugging the o2 sensors thows the engine into a "dumb" mode that masks it apparently. There must be some kind of program in the ecu that can compare/combine the timing from each bank that gets overlooked with the o2 sensor unplugged.

 

No, that wouldn't make sense, you don't have a misfire, and computer doesn't have a "limp" or "dumb" mode just open loop and closed loop, and with O2 sensor unplugged it would stay in open loop and that would also SET A CODE after 5 to 8 minutes of warm up time
There is no way I know of to disable code setting in a Ford computer

And O2 sensors have TWO parts
The sensor, 2 wires
The HEATER, 2 wires

The heater has key on 12volts and then is Grounded by the computer, so the computer SEES that 12volts passing thru the heater coil with key on, if not it will set an O2 HEATER Code right away
And each O2 heater has its own ground wire back to the computer, so any unplugged O2 should set a code of its own
So each unplugged O2 would set at least ONE code

Open Loop is when the computer runs off factory settings in the computer, like when engine is cold the O2 sensor can't work until they are heated above 600degF, which is why they are "heated O2 sensor", so they will get to 600degF faster
Once the O2s are working the computer changes to Closed Loop, computer then calculates air/fuel mix on the fly, for best MPG and best power, because it has Feedback from the O2 sensors
If you unplug an O2 sensor, computer switches back to Open Loop and uses Factory air/fuel mix tables in memory
And it would set a few codes, like being in Open Loop when it should be in closed loop, and codes for sensors that caused it to switch to open loop

I don't think this is just a mechanical issue

 

Thanks for clearing that up.

I think your right on it not just being a mechanical issue. Someone really did their homework when researching how to “F” the next guy. Regardless of who’s going to be responsible for the cost of the repair it’s going to have to be repaired. I guess when the dealership that I prefer to do the repair has the motor out they can figure that one out too.

Am I the biggest sucker ever to post here? Maybe..It there a contest for the biggest nightmare ranger on this site? I think I can compete.

 

Buying a vehicle is always a roll of the dice, new or used
Used would always be a bigger gamble just because things do wear out

I have bought new vehicles that HAD TO BE taken back to dealer many times in the first few years, recalls and other issues, even towed once or twice when they broke down on the road
"Free" repair doesn't compensate you for the inconvenience and time, most would rather not have any issues, lol

I only buy used now, 3 years old for the wife or kids, these usually have all the recalls done and 3 years is when the Lease returns hit the market so prices tend to be lower.
I like older myself

You would only be a "sucker" if you bought another vehicle from the dealer you got this Ranger from
And in fairness they may not have known there was a problem, which is a good reason NOT to buy from them again, they don't check out the vehicles they sell
And they may have known and didn't care, so not reputable
Neither is your fault so not on you

No, there are worse stories, lol, but this Rangers issues are interesting, so sorry for that

 

Strange new development. New to the board here and found it last saturday but just forgot to post it.

The fact that the truck just wasn’t throwing any codes was eating at me despite being at 2 separate dealerships. I know there are other and seemingly more important issues to look over when there but it was something that I brought up with both of them and neither had gone so far as to take a look at that particular issue and just elected to address the other more (seemingly) simple ones.

So I’m poking around like I like to do and this time I’m in the fuse box under the hood. I notice that there is an empty spot for one of the fuses and decide to look it up in the owners manual. Huh…Wouldn’t you know it..PCM fuse. It’s missing. I don’t have a #15 fuse handy so I throw in a spare #10, start it up and take it for a drive for a few miles and see if it will generate a code for the currently still unplugged b1s1. Yep..I have codes now. Basically o2 sensor and PCM comm codes and that makes sense since the truck was running with the PCM offline. I clear the codes, plug b1s1 back in and head for a drive to see if I get the power cut issue and/or any new codes That may shed light on why some idiot would pull both upstream o2 sensors and the PCM fuse.

Nope humming along just fine. Power cut issue gone and I notice a considerable bump in power past 3k. I drove about 20 miles and strangely I’m happy to see the check engine light pop on. I get home and read codes and all I have now are p0420 and p0430. I guess running it without the PCM and 2 upstream o2 sensors fried the cats? Regardless, this really hammers home that this was intentional and I’ll just leave it at that because I could type some things out now about how feel and all lead to varying jail terms and getting my 15 mins of fame.

Now I’m sorta (well not sorta, definitely) questioning anything either dealership has said to me about their diagnosis since they can’t even determine that the fuse for the PCM was missing. It’s going to take a little bit for me to get it into this guy but I have an appointment in about a week and a half with a very respected local mechanic to give it a once over and give his opinion on it. I’m putting a lot of hope into it but honestly if neither shop was able to identify the PCM fuse issue how good are they at troubleshooting an issue really. And just maybe everything is ok with the timing and cassettes. They were just doing it wrong. I’ll spend the extra couple of hundred if it gets me out of spending $3500. Right now with everything plugged in it runs great, gets great gas mileage and has enough power to get a little tire squeal off the line if you mash it from a dead stop so is the timing really off? Again, I’ll go back to a 2010 with low miles and never had the startup rattle.

Ultimately if all that winds up being bad are the cats (fingers and toes crossed) and that’s what they were trying to hide by doing all this, I don’t care and I’ll be happy to finally be at the bottom of all of it. I live in a state without emissions check so I can address that myself with my welder if I can’t get a good enough quote from a shop on magnaflow universal replacements. Ford pricing for replacement cats is just offensive. I’ll update when I get it back from the local shop.

 

It won't run without the PCM since it controls spark and injectors

But what might have been happening is that the codes couldn't be Stored in memory, PCM Memory has separate fuse, full time power, to retain LTFT and codes with key off

Now the CEL should have come on when driving, but no codes after key off, but maybe Ford has changed that

What was the fuse number in the engine bay box?

 

When I was explaining it to the local mechanic he sort of had the same reaction. It was fuse #39




Edit to add:
Maybe PCM is getting something from fuse #21?

 

Engine shouldn't start with fuse 39 unplugged, from my diagrams that is the PCM's main power fuse, key on power
Fuse 21 is the "Keep alive power" that holds memory

I am using a 2008 4.0l wiring diagram, 2008 owners manual shows the same fuse designations as 2010

So very perplexed

Pull fuse 39 AND 21 and see if engine starts, curious if PCM will pull power from 21 if 39 has no power, like a backup circuit

 

Been a while since I posted status on this but still working on it. Just picked it up from the shop after paying 3500 for all timing chains getting replaced. Runs pretty smooth now with compression back up on 1 3 and 5. I don’t want to deal with it today but tomorrow I’m heading back over to the dealership that sold me the truck to tell them that they are going to replace the catalytic converters on their dime. It’s Minnesota state law that a dealer has to make sure that the emissions system is in working order and I have pictures from when the engine as out that are looking down the neck of both converters and they are empty. So that’s why fuse 39 was missing. Someone was intentionally (in my opinion) trying to hide the hollowed out cats by suppressing the CEL lights and selling to the dealership or the dealership selling to me.

Normally I wouldn’t care about the cats being hollowed out since I live in a state with no emissions checks so this is just me getting them to pay something for ripping me off. After that I’m going to try to reclaim some of my 3500 in small claims too so we’ll see where that goes. I know it’s a long shot but I have a case (and evidence) here where there was deliberate attempt to hide issues on a truck for sale from a dealership.