MECHANIC: A Ford Fiasco · 2:12am Oct 27th, 2022
No, that's not Ford's new model.
It is the third vehicle for this customer I’ve worked on. One of his others is also the subject of a blog post, which I just now realized.*
But first, you know what to do! Grab a drink and kick back, we’re going on an adventure together!
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*His third vehicle could be, too, if catastrophic structural rust was worth blogging about. Also the other blog post isn't published yet, so it's not linked.
The vehicle in question is a 2011 Ford E250 extended cargo van with an automatic transmission and a two-valve 5.4L engine. It’s here because it runs rough on startup and sometimes stalls. Usually once it gets past that, if you feather the throttle, it clears up and runs fine. The check engine light is on, as are several others (ABS, Traction Control, TPMS, and the wrench light).
This thing arrived back in early August, and while I have a few blogs about vehicles from further back than that which I haven’t finished or published yet, this particular van is still at the shop, although as of today it's officially repaired.
I’m mentioning this because I didn’t bother to keep track of everything in the process.
I’m also not the first mechanic to look at it and try to address this particular problem. But I’m the one who fixed it, and a few other problems it acquired along the way.
The van was first given to our new tech, the one who quit while I was off at Everfree Northwest. He pulled the codes on it, and discovered that one of the codes was a P0340, a camshaft position sensor performance code. It also had a axle ratio/tire size mismatch code, VIN mismatch codes in various modules, and its original PCM sitting on the front seat. The center console had an empty box which had once contained a camshaft position sensor.
We’re not the first ones to have looked at this thing.
But.
It’s a nice softball for our new tech. We don’t know how good he is at diagnosis.
It turns out, he’s not great, and it also doesn’t matter because he’s gone. But we’re getting ahead of ourselves here.
Now, I won’t bore you with getting too technical about how cam sensors work. Basically, you’ve got a reluctor of some sort—usually a metal thing with teeth, or raised spots on a cam gear or maybe a magnet, and whenever something passes that sensor, it sends some kind of pulse to the PCM, which uses it to determine the speed of camshaft rotation. The faster the cam rotates, the faster the pulses come.
The computer knows what a good signal should look like (for example, it might expect to see a 0v-5v square wave), and it can also compare to the crankshaft position sensor. Since the crank and cam are connected by a chain, their rotational speeds ought to match with only slight variation. If it saw that the crank was spinning at 1000 rpm and the cam was spinning at 10 rpm [the cam should spin half as fast as the crank], it would know something was wrong, and then it would use other sensors and logic to figure out which sensor was lying.
When it does, it’ll flag a code (in this case, P0340) and go into failure management mode, where it uses other sensors to determine the engine’s rotational speed. Certain other codes will be blocked; it can’t test for them if it can’t keep track of cam and crank correlation. If it had variable cam timing (this engine doesn’t), that would stop working.
I’m not even working on this van, and I already know why it’s behaving like it is. It probably wants to control some engine stuff based off the cam sensor, and that goes badly, and then it figures out the cam sensor isn’t working right, flags the code, and then ignores what that sensor tells it.
And, assuming that the other shop followed a good diagnostic process, this should be a softball. There’s only one component they haven’t inspected or replaced, right? The wires between the cam sensor and the PCM.
Our new guy goes down that diagnostic path, figures out that a wire is broken, and runs a new wire.
In a perfect world, we’d pull apart the loom and inspect all the wires in it. Maybe one’s rubbed through and not transmitting a signal any more, and a bunch more have broken insulation and corrosion. But it’s a van, it’s hard to get to things, and the loom goes everywhere and it takes a while to get it off the engine and into a spot where it could be inspected.
So he splices in a new wire to take the place of the (presumably) broken one, hooks it up, and that doesn’t fix it. That does nothing at all.*
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*That did do something, but it would be two months before the something it did was discovered.
And with that it becomes my baby.
I find out that this van has been diagnosed for this problem before but hasn’t been fixed. We try a new cam sensor—it’s possible the one that was previously installed happened to be bad (it wasn’t). I’m a bit suspicious of the PCM in it; the VIN mismatch codes and the axle ratio/tire size code suggest it wasn't programmed correctly, that it was a pre-programed unit.
Going onto Identifix, I do some searching and find out that Ford changed the cam gear in 2008 (or so). The old design had only one trigger for the cam sensor, the newer design had eight (I think; it was certainly more than one). If an older model cylinder head, camshaft, or engine were installed, it would not generate a signal that the PCM would understand.
I ask if the problem started when the customer had a new engine installed (it doesn’t look new, but you can’t see much of it since it’s in a van).
He just bought it and doesn’t know anything about its history. I should mention that the van has over 300,000 miles on it (483,000 km), and it’s unlikely but not impossible that a 5.4 would have lasted that long in a work van.
Either way, it’s easy enough to check. If I rotate the engine over two times, the cam gear should rotate once. Someone up top can look through the hole where the cam sensor is mounted (after it’s removed) and count the triggers on the cam gear. If there’s only one, it’s the wrong gear. If there’s more than one, it’s the right gear.
Now, with the engine in the van, getting a clear line of sight into the hole isn’t easy, but that’s why they make mirrors and cameras on a stick (a boroscope). My manager takes position, I lie on the ground and start turning it over, and he says that there is only one trigger.
(I shoulda taken a picture of the cam gear; maybe I’ll post that later for your edification.)
Now we’re gonna skip ahead to last week, when the now-diagnosed van came back in to be repaired. The customer had agreed to replace the camshaft [the old design cam gear is press-fit onto the camshaft; the new design is bolted on, so you have to replace the camshaft in order to replace the cam gear], and since we were digging into an engine with unknown mileage and maintenance, it’d be really stupid to not also replace the timing chain, tensioners, and guides while we were in there.
I won’t bore you with details of the job (if you’ve got a hoist, it’s not bad, with the exception of removing the right side valve cover). When I removed the doghouse (engine cover) in the cab, I noticed that the left side valve cover had a manufacture date on the back—March 2004 (which is before 2008). Confidence in my diagnosis is increasing.
The other valve cover had the emissions sticker on it, covered in grime. It also said that this was a 2004 engine.
Unlikely that it would have gotten two used valve covers off an older engine, but of course I can’t rule that out.
The moment of truth would be when I pulled the front cover. I’d get a good look at that gear, and then I’d know.
It only had one trigger. And I could get the new gear out of its box and compare them side-by-side; they were different, and the new one (the one that Ford says this van should have) had the eight-ish triggers it was supposed to instead of just one.
Spent last Friday putting it all together, fired it up, and while it didn’t have the stumble, it did immediately set a P0340 code.
If you ask any mechanic what they hate the most, it’s either putting together something somebody else took apart, or it’s diagnosing something that’s been misdiagnosed multiple times. I’ve spent far longer than I wanted to since I got back from Everfree Northwest putting together things our former mechanic took apart (and there’s still one more to go, sigh) and now I’ve got this to deal with.
On the plus side, I saw with my own eyes that it had the wrong cam gear in it. That wasn't just a ‘maybe this will fix it’ Hail Mary parts toss, that was a legitimate problem. No matter what else is still wrong with it, it could not have been fixed without replacing the cam gear.
Today I got to dive back into it, while I was waiting for parts for the timing chains I’m doing on a newer F150.
The manger and I had discussed it during the early parts of the week. I thought we should get the Ford tool and reprogram the new PCM, just to be sure that wasn’t the problem. I didn’t think there was much chance it would be, but that could also fix the VIN mismatch codes and the axle ratio/tire size mismatch code. He didn’t want to ask the boss for the IDS.
I also thought that we should replace the connector for the cam sensor. It was missing its rubber weatherproofing, one of its wires had been spliced (the one our former mechanic fixed) and the other one had some insulation stripped off, probably from the previous shop—the one that had installed the PCM—attempting to diagnose it.
We didn’t get a connector.
I pulled the cam sensor, and while it was from NAPA, it had a Ford part number on it. That wasn’t the part number it should have had, and in fact that part number came back to a 2007 or 2008 Ford. The one with a single trigger on the cam gear.
There are different technologies of sensor that pick up the trigger pulse; could this one not make a signal the PCM could recognize? We ordered a new sensor.
I wanted to put the old PCM back in it, but we didn’t have the IDS, so I couldn’t make the vehicle like it (if I installed the old one without security access, the security system wouldn’t let it start).
My manager offhandedly suggested I test the wires; he said that our former tech had said something about a broken wire. I thought to myself, yes, that’s why he spliced in a new one, but what the heck, it’s not hard to check.
One of the easy ways to test the integrity of a small automotive wire is to see if you can light a headlight with it. I don’t remember off the top of my head, but a headlight bulb pulls more than five amps, and a cam sensor doesn’t require (or send back to the PCM) nearly that much amperage (it’s probably milliamps), so if the wires are good enough to light a headlight, they’re also good enough for the sensor to work. You can test any circuit that runs something which draws less than a headlight’s worth of amperage that way, but if it’s a computer controlled circuit, make sure it’s unplugged from the computer before you try (and obviously, the component on the other end of the system).
My idea is to plug a headlight bulb in place of the cam sensor, and then access the terminals at the PCM (the harness side) and feed them twelve volts from a fused power source. If the headlight bulb lights, the wires are good. If it doesn’t, they aren’t.
It’s a perfectly cromulent test.
I set it up, send power (and ground) down the wires, and the headlight
doesn’t illuminate.
The PCM in this vehicle has three connectors, labeled (if I remember correctly) C175b, C175e, and C175t. That last one runs the transmission, and as I’m typing this out, I’m wondering if b runs the body and e runs the engine. I don’t think that’s the case, but it might be.
Two of the connectors have fifty or so wires (not all the cavities are populated), and the third has about thirty. With that many different wires, even if you’re using tracers (stripes) on your different colors of wire, there’s going to be some overlap.
Which is a roundabout way of saying that our former mechanic spliced the wrong wire. Remember how early on I said that his splice would cause another problem which wouldn’t become apparent until later on? He cut a wire that feeds the throttle control, so now the throttle was getting a camshaft signal that it didn’t know what to do with.
Removing his ‘repair’ wire and soldering the correct wires into their proper places fixed the P0340, as well as the throttle problem. I pulled the vehicle out front and the manager set out to test drive it . . . then he came back in and asked me about the ABS light and the traction control lights.
The ones we’d known were on due to the PCM being improperly programmed.
I won’t delve into the programming process here, but it had its own twists and turns. However! At the end of the day (not figurative, literally today [or yesterday, depending on which time zone you’re in]), the van did not have an axle ratio/tire diameter or VIN mismatch code, and the ABS and traction control lights were off.
Unrelated to the story, but that ponified version of Flood is amazing and I'm definitely replacing my CD cover with it! (I already have a custom version of Lincoln with Celestia & Luna on the cover!)
I have such confidence in automotive engineering, or at least I will have some degree of confidence when they make a 'low tire pressure' sensor that doesn't promptly go off every fall when the temp gets below 40. My work car and two personal cars are all lit up, and the tire pressure has been examined to a stupid degree. Self-driving cars, hell. I just want one that inflates its own tires until its happy with them.
Based on the book The Reckoning & my personal experiences back in the 1970s, if you've got a still functional pice of Detroit tin with that kind of mileage you can thank Japanese car makers.
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You sure? Because vehicles that do that DO exist. The wheels are just a nightmare to do anything with and all the examples I know are military or similar vehicles... You can find it on some more extreme offroad vehicles too though.
Such fun. At some time I need to finish replacing and rewiring a combine harvester's lights. Something of a hack job... and figure out what's going on with the automatic ground pressure for the grain head that doesn't work. Useful for harvesting soybeans, where the head has to be pressed to the ground... but of course fields aren't parking lots.
The same machine has broken wires and/or sensors for various sections of the thresher. When working correctly, they inform the operator if something isn't working before something gets damaged.
A previous owner had also replaced the breathing cap for the fuel tank with a thread tap jammed into the hole. While it might have been fine for harvesting corn due to it not being very dusty, dust from wheat and soybeans gets down in there. Oh, and we'd lost the fuel cap in the field while doing wheat once, resulting in about fifty gallons of diesel being turned into furnace fuel. A lot of the particles, such as wheat hulls, are too big to get through the valve under the fuel tank that goes to a sediment bulb. Hopefully the bit of window screen backed by a rag will filter the air well enough to last through the rest of harvest, after which point I will be able to fix the breather properly.
The Case 340 Magnum with loosening bolts definitely is messed up-- an unintentional experiment happened where when pulling a stuck truck gently with the drawbar resulted in the transmission bolts loosening again, while the dozer blade was just a front counterweight, unused. I strongly suspect the bolts were not installed correctly, and that the MFD (effectively, four-wheel-drive) is causing the tractor to pull itself apart. The machine will have to be partly disassembled (cab lifted, fuel tanks and lines removed, etc.) to get at all the bolts. I am very tempted to do it myself; a shop manual and stands/carts and assortment of tools will likely be less than the cost of having the dealership do it-- and I am not confident that their mechanics will do a good job, given other pieces of equipment they took apart and reassembled also had bolts loosening up (a skidloader with a rebuilt control valve assembly working loose, and a different one with various hydraulic lines that were loose).
Then there's the boneheaded thing I did yesterday. The fan shroud was taken loose on a Ford 8000, and some of the radiator bolts removed to try to get an air cooler off to clean chaff and dust out from between them. The truck was still mobile, and needed to be moved out of the way for a different job (brakes on an '05 Expedition). So I thoughtlessly fired up the big truck... whereupon the fan chewed itself up on a conduit with an air line going through the middle of the shroud (?!) and putting a pinhole leak in the radiator. The machine already had the plastic coolant reservoir crack and leak, resulting in overheating... feh.
No more jumping between tasks like that.
I wonder if they could do an SCAUX variation over just a few emergancy variations so that between normal, hi, lo voltage and dead, forward, back current flow they could just use a low wire hard network related to LAN. I mean, if a 32 bit CPU can handle over 30 thousand channels of light and sound in a theme park from a single home computer, youd expect them to have sorted a car out by now?
Hell, a Rocket launch telemetry feed isnt any more complex. After all, it was handled by the same model of computer.
Strangely, it is possible to have a computer powerful enough to do such things, and yet it cant play DOOM,
Since August? That's a long time to have a vehicle at the Mechanics.
Looking at the ponypic with the wall of cables - that's not a recording studio, that's a wall's worth of tech that has a studio sideline.
I have this image of the IDS deep in the jungle, poison blow darts and pressure-sensitive traps protecting it Indiana Jones style. Also fantastic typo for manager (if on purpose).
Yay! for making all the bad lights go away.
This is why I drive old card without much in the way of electronic weirdness.
Incidentally, are you familiar with the Just Rolled In channel on Youtube? You might find it entertaining. Or nightmarish. Depending.
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When I first came across it, I recognized that it was a ponified picture, but couldn't remember why I knew it. It's a fantastic picture, and I love it very much. It wasn't topical for the blog, but I knew I needed to share it.
Maybe 'cause I think about Sweetsong hoboing her way across the US, but I almost got the vibe that the pony in the Flood picture is happily rafting her way down the Mississippi in her improvised boat.
5694735
You could buy a Canadian car that has a snow tire mode (if it's cold and it can't read the tire pressure sensors, it doesn't warn you), or you could buy a HUMVEE or other similar military vehicle that does have self-inflating tires. Some semi trucks apparently have self-inflating systems, too.
5694736
I don't think that's true, although I admit I haven't read the book. I don't know what, if any, Japanese influence was in the Chrysler 5.2 in my Ram or the GM 2.5 in my S-10, both of which got close to 400,000 miles. As far as I know, both engines are original in those trucks. The Chrysler engine dates back to the 60s, and the S-10 engine dates back to the 70s.
There was a lot of influence in what other nations and automakers were doing, of course, and that's not a new thing.
5694864
The company I drive for has self-inflating tires on our trailers. It's fantastic when you have a leak because you can limo to safety. I once had to navigate downtown Phoenix with a leaking tire to get to the terminal. As stressful as it was, it is far better than a blowout on the freeway!
5694761
Heh, one of my upcoming mechanic blog posts involves wiring new rear lights on a Ford dump truck.
It's funny you mention this; I know about all the sensors on cars and what they do, and I've got enough interest in aviation, trains, and boats to know a lot of that technology, but I've never really thought about farm equipment beyond the most obvious stuff.
Can you not get the correct breather cap for it?
Cars and trucks have systems to capture the fuel vapor and reuse it later, with systems getting more sophisticated from the 70s on; I would assume that there are some emissions requirements for farm equipment too, but I don't know if they have closed fuel systems now.
There must be something going on with the bolts loosening. How much of an online community is there for tractors? I can find lots of stuff for cars using our professional resources as well as some online forums for weirder things. If it is a common problem with them, you'd think that there are other people who have figured out solutions (which I suppose could be 'sell it to someone who doesn't know about its problems'). There are ways that airplanes use to tie off bolts that can't be allowed to work loose which might also work on the tractor . . . or might not, since it's a very different use case.
That's a problem with multitasking. I was jumping on and off a timing chain job on a F150 the first half of this week, and there were a few things that got done less optimally 'cause I started an operation, got pulled off the vehicle, and then when I got back to it I forgot where I was. Given that this isn't new for me, I have a few tips and tricks to help keep track of what's been done, what needs to be done, etc., but it's not foolproof.
It is best to avoid it if you can.
5694765
The big challenge that faces onboard computers on cars is their operating environment. PCMs are usually under the hood, which means that they have to be able to withstand temperatures of -60F (-51C) to 200F (93C) or maybe more, be able to survive being immersed in water, covered in dust and dirt (so they don't have any external ventilation), be immune to all automotive fluids that they might encounter as well as all automotive chemicals they might encounter, survive shockloads, and work reliably for at least two decades with zero maintenance--and they generally do. My current fleet (that has engine or other computers) was built between 1988 and 2007, and all of them are still rocking most if not all of their original computers (I haven't replaced any on any of my vehicles).
Any system also has to meet SAE standards and fit with the scan tools that the manufacturer currently uses. Most stuff now is laptop-based, but a lot of them are running cloned 90s equipment on the laptop (which means that the GM tool has to install outdated versions of Java on itself in order to work).
I figure at some point we'll have another major update to scan tools but I don't know when it'll happen. For now, they're still using the interface that was developed in the 90s and future-proofed to a surprisingly good degree. Some of the infotainment modules on cars use USB now.
5694774
It is. Between waiting for parts and waiting for an available mechanic, that's kind of how it goes.
Just today, I finished a Jeep that's been waiting for over a month for a part. We've got one in our lot that's been there since April and it waiting for an engine computer that nobody has.
Heh, you're right, it totally is.
The typo isn't intentional, but I'll leave it 'cause I'm also amused. We don't have to fight traps to get the IDS, but what usually happens is we ask for it, it eventually shows up, and five minutes later the boss asks if we're done with it, 'cause they really need it back. Same goes for practically every other tool. The downside of this is that it's really frustrating when I know we've got a tool to make a job easier, but for whatever reason we can't get it.
There's still a couple that the owner doesn't care to fix, but the majority of them are gone. Soon enough, the van will be gone, too.
5694867
Basically, The Reckoning (Halberstam) makes the point that Detroit used the concept that cars were updated every year & should fall apart so people would have to buy a new one. Ideally, the biggest one possible with as many options as possible.
The Japanese realized that you could make a cheap car, sell a lot & make a living that way.
Not any specific features, just the idea that you shouldn't have to buy a new car every year.
5694834
Even if you think you're escaping electronic weirdness, you probably aren't. Unless your cars are really, really old (and some of the older stuff had their own electronic weirdness). Even with non-computerized cars, splicing the wrong wire will not fix the problem the car has.
Legit, modern cars tend to be more reliable than older cars (since computers tend to be more robust and adaptable than strictly mechanical stuff); I don't tend to write blog posts about cars that aren't broken, since A: we don't get them at the shop, and B: that's a boring blog post.
Yes, I am, and I've seen a few cars that would fit in that channel. Just a couple weeks ago I drove an Escape into the shop that had a broken frame . . . at least I was driving it in to fix the frame. As you'd expect, it didn't drive well.
5694873 So tempted to write a story where the mechanic is attempting an unauthorized repair on a 2050 John Deere much like a bomb disposal technician works their way through trembler switches and poisoned needles-- Urk!
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Shhh...! Do not give them any ideas!
(Though I imaging that would make for a fun Applejack + Daring Do story)
5694900
Do it!
Maybe a unicorn, working with the Earth Pony who owns the tractor?
5695292
Heh, I imagine it ending when Daring Do gets to the PCM, pulls it out of the vehicle and tucks it in her saddlebag . . . at which point Applejack realizes that she might be good at getting forbidden artifacts, but she's not a great mechanic.
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Definitely. When I have the time, I'll pull it off the parts machine. Farm equipment tends to lag behind automotive emissions, and this machine was built in the early 80s.
It's been hit-and-miss, mostly the latter, for online things. Mostly what I tend to get in searches are shady suppliers of shop manuals.
I've seen various ways to lock nuts and bolts down, such as folding a tab of metal over the head. Given these are 12-point bolt heads rather than six or four, that's not much of an option. I'm also very leery of adding lock washers or such, and shorten the length of bolt in the threaded half. I'm hoping that disassembly, cleaning of the holes, and use of a modest thread locker all the way around will take care of the problem.
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The one farmer I know decently well has an small farm and a lot of old equipment (that's how I know him; they've still got a bunch of horse-powered stuff which has been 'modernized' to be pulled with a tractor). I do know it lags behind, I'm just curious what the new stuff's got.
It would seem like there would be communities of enthusiasts, but perhaps not. I can say that there are some difficulties with finding good forums even for common stuff--I was looking up torque specs for a Ford when our internet was down, and found a couple sites that quoted what were obviously incorrect specs. A good thread locker might be your solution; you could also paint a stripe on the bolts so you can see more easily if they're starting to turn.
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Good advice, thanks!