97 SOHC XLT No Spark - No Start - Does Crank. 6 hour drive then parked overnight. No other issues that show obvious.

[Metalface]

Ok! So here's a wild one.
And before you say it. I am indeed suspecting the Crank Position Sensor first, but haven't gotten to it.
97 XLT SOHC V6 **No timing chain rattle**

We drove 2.5 hours to B from A, screwed around for an hour at A so add that to the driving, and then 2.5 hours back to A.
So we did about ~6 hours of driving. Parked it overnight, came out in the morning to go buy tires (lol) and it cranked but wouldn't start.

First thing I checked was fuel pump stuff:
-Can I hear the pump? (yes, not as much as usual, but definitely yes.)
-Fuel filter? (Replaced less than a year ago and the old one was ok. Was hunting a different issue which wound up being the coil had a crack in it that I couldn't see.)
-Fuel pump fuse? Looked good -- even swapped with another 20A, and still nothing.
-Fuel pump relay? Looked fine, replaced anyway.
Upon initial ON position with key, you can hear the pump start.
I checked the inertia / tip over sensor. Nope, looks fine, no burnt wires, not pressed out. It's totally all good.
Then I checked the fuel rail. Yep fuel. And yep, extra fuel comes out when the key is turned to ON. So we are getting fuel, or enough for it to at least try to cough.

Absolutely no firing of any kind is happening.

Then I checked for spark. No, no spark.
Okay, so why?

Looked into PATS stuff, turns out (says a thread on this forum) 98 and up has the key transponder, we don't even have one.. So it's not that.
No theft light.
Only had a code for a "Small evap P0422" and have had that on and off forever (bad carbon box) but we get fuel to the rail, so..
No flashing theft light. No theft light code. So hmm..

Tried starting in Neutral, nothing there either. Had my neighbor pull the throttle to ignore the TPS and still nothing even in neutral. I had not yet discovered no spark, but that's what I checked next.

Tried unplugging the main computer and plugging it back in. Yeah.

So, now I'm trying to do some mental detective work. Ok, did it behave weird on the drive? Has it been weird at all?
Nope! No weird behavior. Always has had a tiny little misfire that hasn't been out of spec to trigger a code, and that's only at idle. I'm chalking that up to being nasty old injectors among other 25 year old vehicle issues.

So I'd really go as far as to say, we parked it, and it left the chat.
I had initially suspected we got the fuel pump (((or SOMETHING... we will probably find out what...))) really hot and then because we didn't idle after our epic journey, it didn't get a chance to cool itself down. But at this point, if the fuel pump is damaged, I don't care to worry about that yet, because no spark.

So it boils down to now that we have:

-Cranks just fine.
-But.. no spark....
-Did not overheat. 100% certain. Has never overheated.
Also did not fade or shut off or anything!
-Never had timing chain noise or rattle.
-NO theft light.
-No theft light codes or flashing light.
-No PATS system to begin with and our key certainly never had a transponder chip.
-Completely fine running conditions prior to parking overnight. No fading no hesitating no weird idle no loss of power no overheating, nothing.
-No rodent activity and a very well greased frame that pests would hate, parked in a location where rodents wouldn't be interested anyway..
-No tripped inertia sensor.
-Fuel getting to rail.
-Stock Anti-Theft with No Issues for 3+ years that fully functions as from factory with no modifications at all.

And, here's things that have been replaced since we got it at 120 ish K miles (now at a little over 200k) when we were hunting down what was actually a cracked coil / cap:

Replaced sensors and etc that might have to do with something like this:
-MAF sensor
-Intake manifold gasket
-Fuel filter
-Throttle Position Sensor
-Spark plugs (we saw some truly horrible things down there. we won't speak of that.)
-Coil / coil "cap" ****but not spark plug wires.****
-other things I may be forgetting and will edit here if I need to!


So. In my life experience I've learned that heat cycling the living hell out of parts and computers (because I have an IT and electronics background before anything...) is not awesome for them, especially after already existing near a warm engine for 25 years. I really do suspect it to be the Crank Position Sensor. Do we know if it is prone to taking a massive dump after a certain # of miles, or excessive wear?


And, my biggest question..

Why the hell would it be completely fine before parked, and then wouldn't start with no spark in the morning?

Thanks guys! Know that was a lot but especially when it comes to completely out of the blue stuff like this, forensic / detective work helps A LOT and knowing what is and isn't wrong helps narrow it down. I do fully intend to replace this sensor. You'd have to rip my Explorer out of my cold dead hands before I got rid of it or didn't fight to get it back running again. Especially since it's never had issues like this before. Also, chance of it being the coil...? Could replace. Is that likely? I figure it would be "as likely as any other truck" but then I think, maybe there's something we all know here that I haven't been aware of yet.. haha. Ty for any replies and ty for the time and thought spent on my silly little issue.

 

[C420sailor]

Got a code reader? When my CKP sensor **** the bed, it would read 0rpm while cranking. With the new sensor, it was like 150-200 I think.

 

[J_C]

I agree, time to hook up a scan tool capable of live data, OR, if you probe the sensor wires with a multimeter, while cranking you should get a low voltage AC pulse... or maybe it's DC, the wiring diagram shows a plus and minus symbols. If it's more convenient you can measure for that signal at the PCM on pin 21 (dark blue wire, positive) and pin 22 (gray wire, negative).

 

[Josh P]

The check engine light should illuminate while cranking, provided the bulb isn't burned out. Need a multimeter to check for voltage at the coil.

 

[Metalface]

Got a code reader? When my CKP sensor **** the bed, it would read 0rpm while cranking. With the new sensor, it was like 150-200 I think.

Good point! Will check tomorrow. Have to recharge battery spent all day draining it by cranking and testing things.

The check engine light should illuminate while cranking, provided the bulb isn't burned out. Need a multimeter to check for voltage at the coil.

Got it. Will check that too. Fairly sure it was doing that, as it always does, but I will double check.

I agree, time to hook up a scan tool capable of live data, OR, if you probe the sensor wires with a multimeter, while cranking you should get a low voltage AC pulse... or maybe it's DC, the wiring diagram shows a plus and minus symbols. If it's more convenient you can measure for that signal at the PCM on pin 21 (dark blue wire, positive) and pin 22 (gray wire, negative).

Yeah, my tool does live data, just didn't know what to look for. Now that I know it should show 0RPM if it's a cooked sensor (duh.. should've thought of that huh.. lol) then that would be easy to detect. And ok, got it, thank you for directing me to which wires/pins to check!!

Thanks guys, will report back tomorrow morning/afternoon EST lol.

For a new PCM/ECM/Main Computer however we want to call it, is there any obvious common knowledge on reprogramming them / getting them reprogrammed vs the dealership? I don't particularly love the thought of taking it to a dealer if it winds up going from
Crankshaft Position Sensor -> Not the cause of the problem -> ECM Replace -> Needs reprogrammed because the issue was the main computer...
I'm guessing there's a silly little tool that will cure my silly little problem if I need to match the VIN and everything on the new computer if that's what it winds up being. Maybe there's a service? Like I said, would go the dealer route, just reallllly don't want to... lol I'm very green when it comes to dealing with this sort of thing, so any info is appreciated, thanks!!

Edit:
Ok so important question -- is there anything I should know in the way of those particular parts/wires/pins etc being prone to failure? Have we heard of that? I haven't, personally.. Long time lurker of the forum just don't post at all. Any info is golden.
By 200k is this a normal thing to have to deal with? Is there, maybe a ground strap that I need to check or should be looking out for that might deal with this issue not coming back to me? This particular Explorer used to be used to transport jet skis and would have its pretty little ass dunked in the bay on a regular basis. So salt and corrosion is a real concern, I haven't dealt with any of the grounding straps that may just be totally missing underneath... Ask me how I know. Lol

Thanks again everyone I really do appreciate it

 

[J_C]

IMO you are getting ahead of yourself. Check the sensor and go from there.

It is unlikely your PCM is fried but there are services that can take the programming off your existing PCM if it's just some subcircuit and transfer to a compatible replacement.

Anything is prone to failure after 26 years, and as well as checking for the signal getting to the PCM, if it doesn't then you can also check for resistance/continuity from the CKP connector and the connector at the PCM, and check that neither are shorting to chassis ground, though I'm not entirely sure if the negative lead from it is floating from chassis ground or not, wiring diagrams don't make that clear, but there are probably youtube videos on how to check same/similar model year Ford CKP sensor circuits beyond just the sensor itself.

There's a 2nd gen workshop manual linked in this forum as well, also in my sig below which might be useful. There may be some tricks to get it to work in the posts in that forum topic. 1996-2001 ford explorer / mountaineer workshop manual (5567 pages!)

Also, try this: 2nd gen issues? Try this first!

 

[Metalface]

IMO you are getting ahead of yourself. Check the sensor and go from there.

It is unlikely your PCM is fried but there are services that can take the programming off your existing PCM if it's just some subcircuit and transfer to a compatible replacement.

Anything is prone to failure after 26 years, and as well as checking for the signal getting to the PCM, if it doesn't then you can also check for resistance/continuity from the CKP connector and the connector at the PCM, and check that neither are shorting to chassis ground, though I'm not entirely sure if the negative lead from it is floating from chassis ground or not, wiring diagrams don't make that clear, but there are probably youtube videos on how to check same/similar model year Ford CKP sensor circuits beyond just the sensor itself.

There's a 2nd gen workshop manual linked in this forum as well, also in my sig below which might be useful. There may be some tricks to get it to work in the posts in that forum topic. 1996-2001 ford explorer / mountaineer workshop manual (5567 pages!)

Also, try this: 2nd gen issues? Try this first!

Better to know more in advance in case I'm not around!
No, I don't think I'm quite ahead of myself.. to be honest.. All of the threads I have read with my *exact issue, not just issues similar to mine* turned into Crank Pos Sensor, then ECM. So that is what I'm expecting. Prepare for the worst be pleasantly surprised if it goes better than expected. And from the threads I have found, it appears that the route everyone took was once they got to the stage of "uh oh, it's the main computer," they get one and then take it to a dealer. So since unfortunately do not defecate $20 bills, I do have to be vigilant so I am prepared for a potentially costly situation by having to take it to a stealership... lol


The reason I suspect it would be ECM or pos sensor as likely as one another, is everything was totally golden up until a 6-7 hour drive then no time allowed for stuff to cool and then try it the next day to a no start.
In every thread with a failing Position Sensor, they had issues leading up to the failure. I never had a single sign related to this issue, + it was perfectly fine for the 6 hour drive it took before parked. So that makes me equally suspect both, currently.

All that being said, I really do feel like of all things it's one or the other, but I'm directly in the middle suspecting both. I *will* do the sensor first, then ECM later.

I have a 71 year old bed ridden lady that needs me to get to her within the next few days, so I'm trying to load up both an ECM and the sensor and be ready to go in case it's gotta be both to fix the issue. This is my only vehicle and until three days ago had never missed a day of service.. So this is major

Personal situations aside, yeah, you roll the dice with any old vehicle that's for sure. 25+ year old plastics and sensors just die, it is what it is.

Yeah, seen that thread about a million times, sometimes I read it just to know more, but unfortunately it doesn't hit this nail too directly on the head. I've tried threads like
This one, among others. Threads like that are pretty good for this particular issue.

So as far as this;

It is unlikely your PCM is fried but there are services that can take the programming off your existing PCM if it's just some subcircuit and transfer to a compatible replacement.

What services? Link? Info pls & ty

links in sig are helpful so ty for those, will be reading up on those.
At any rate tomorrow I'm gonna take on the task of putting in the new sensor and go from there, ty everyone!

Edit: (and of course, I am fingers crossed hoping and praying that it is NOT the ECM.. I also skeptically doubt it, but I can't help but recognize it is entirely possible via others experiences posted here. And of course, also hoping the sensor will magically fix all my problems. But I can't say one way or the other until I recharge the batt and check everything again tomorrow if it seems likely, so for now, I gotta be prepared.)

 

[Josh P]

Be surprised how often it's the square connector in the engine harness.

 

[Metalface]

Be surprised how often it's the square connector in the engine harness.

See that's some stuff I haven't had to ever mess with yet. Will note that for my epic battle tomorrow morning lol and tyvm

 

[J_C]

What services? Link? Info pls & ty

I haven't made a list of them since I've never needed it done, would start with a google search OR start by contacting one of the services that can do the PATS delete (regardless of the fact that you don't have PATS, it shows their ability to read and flash the firmware), for example:

Ford PATS Delete Service 1996 - 2004 EEC V

THIS IS A SERVICE WHERE YOU SEND YOUR ECM TO US Service for deleting PATS from 1996 to 2005 Ford Engine Computer. Diesels may incur an additional charge. If wanting to purchase this service for a Diesel use the following link: Diesel PATS Delete Service PATS stands for Passive Anti-theft System...

www.garretttuning.com

While I still doubt the PCM is the problem, there are also PCM repair services. Lots to look through with a search like this:

Google Search

Personally, I'd use a vehicle finder database for the closest junkyards that have one, try to find as near a match Explorer as possible, a '97 with the SOHC, get the PCM from it, plug it in and see what happens before trying to reprogram it, or get the part # off of it and look for some for sale, ebay if nothing else. If it doesn't have your VIN programmed in, there are worse things if it still works.... you can go from there deciding what to do.

 

[allmyEXes]

If you replace the Crank position sensor connector, make sure that you have your polarity correct. Ask me how I know? The replacement had two black wires so I assumed that it didn't matter which way that the wires went. I had a 50/50 chance of hooking it up correctly the first time. I didn't.
My old one would sometimes work, sometimes not. It hasn't been a problem since I soldered and heat shrinked (shrunk?) in a new one

 

[Metalface]

So!
It was indeed the crankshaft position sensor.

Battery died on day one of troubleshooting from cranking it all afternoon, no surprise there.. Don't know if I explained that in earlier replies, but yeah. Slowed it all down a lot more than I'd prefer, but.

Of course, I got to deal with a sketchy AutoZone. The manager right off the bat tells me "Oh, this is a three year old battery. In my experience, it won't charge." I was like, HUH? So I said, well, good thing I tested it just last week and it was at healthy voltage. So I guess we'll see. I knew damn well I was going to have to come back there to a dead battery.
So that killed a day. Indeed, she was a bullshitter. I took it to the further away Autozone, they charged it, with no problems, and said yep we know about her. She's a problem.
So. Two days later, and a trip later, here I am.

0RPM on cranking, so I replaced the crankshaft position sensor. And off we went :]


Thanks everyone!!! You were all very helpful. I can now continue on Exploring.

 

[allmyEXes]

@metalxface Your welcome. That will be $20-. Just kidding, however for ~ $20- you can become an Elite member. I think that is how much it is? It makes your name light up in red on the forum users list and allows a person to post pictures in about any section. We like pictures . The guys and gals here have helped me more times than I can count on my 2 hands!

 

[C420sailor]

Nice!

This is why having a code reader capable of live data is so key. My truck had an intermittent CKP sensor, and it only threw a crank position code one time…and I think it was only pending, too.

The 0rpm on crank is a smoking gun.