94 Explorer VIN X V6 runs for a minute and dies

[jadams]

Well I believe it is time to either replace the PCM with a new one or go to the junk yard and test the theory of a bad PCM for 35.00-50.00

I found one locally and the guy wanted $175, I must've sounded desperate or stupid. .... Don't answer that

Have decided to do both. Just ordered one from a salvage yard in Cleveland OH, the ones around here weren't much help except one that suggested car-parts.com a nationwide system of yards. So while I'm waiting for that one I'm going to continue 'playing' with this one. I can get a new from Autozone for $155 or $205 if I choose not to surrender this one for my own amusement/education. Of course I may still have to buy a new one if..........

And you are exactly right testing this part is just a theory, but the probability is now pretty high.

I have found everyones input valuable and you contributed a great deal also, Thanks before I forget. As everyone pointed PCMs rarely go bad, I will find out soon if I am a member of that elite club. I've been working at this thing for 3 weeks, but now that I've been through it (not done yet) I understand the process of troubleshooting a great deal more and how to test components and that I can it correctly.

 

[wyochimneysweep]

at my hourly rate for being at work it would be cheaper by now to replace the pcm then try to repair it

 

[jadams]

Your question about the "response" to heat and then die as it cools / runs is tough because we don't know the exact nature of the "thermal trace".
Heating to a "cosy temp" allows things to work fine. I don't know... lots of possibilities I guess... transistors, IC's to some degree, capacitors maybe, and even resistors... but ultimately, I still feel it is a cracked track / cold solder which is a good "thermal type trouble". As the board or component expands during use, the expansion difference from non-uniformity of heat (ie some areas / components are cool while others are hot ... by large resisters / transistor with heat sinks) puts stress on things. "Uniformly" heating "everything" may result in greater expansion overall such that connection is never lost from the smaller "non-uniform heating areas"

OK here is another idea to help try and sectionalize things. Maybe you can build some form of "air dam" (card board or something) to block the heat / air from say half the board and then try and see if you can find an area that will help a no start condition, turn into a start and run. As you see, I am almost running dry of ideas.... sorry... but my head hasn't given totally up.

PS... those IC's on the side of the case sound like transistor packages and are using the case as a heat sink.... you might want to aim at those specifically and see if that helps.

Since I didn't loose spark, but injector activation didn't that point to CMP or PCM. The PCM directly controls the injectors I thought, but needs input from CKP/ICM and processes that input with the input from the CMP for decision-making on timing and duration of injector pulses.

Thanks for the explanation on the circuit board operation. That clarifies what I should be looking for. I wish there was an availability of a Hi-Res EEC IV schematic. It looks like EECs are a standard/generic format with manufacturers adapting it for their particular needs.

Good suggestion on the air dam. I'll try that next. I think I will first try the;
1) pin/pcb joints and connector to harness area
2) Each side individually, though I think the rapid cooling by removing the bottom of the case indicates the problem may lie there.
3) Try the main board working from the input connector toward the other end of the case.

That sound about right?

 

[94exploroar]

Fuel pump relay

I had the exact same problem. Replaced everything and it ended up being a cold solder in the fuel pump relay. It would heat up and break contact. Cool off and start again and run for a bit... then die. Just try to swap the fuel pump relay with the WOT relay and see what happens.

 

[budwich]

once you were able to "heat to win"... this "exercise" was never about replacing... at least in my mind, it was about "fixing".... If it were me, I ain't got $200 for a board. Having said that, it would be terrible if you get a "replacement" and the problem still existing.... sooooo keep
"playing" and make sure the problem isn't somewhere in the connector which is a "suspect" for "thermal" stuff. Your indicated focuses are pretty good... I would certainly be "smiling" if you can find the "culprit area" and it turns out to be a $1 fix. Time I got... money I don't... and its fun learning... continued good "hunting"... oops stone rolling.

 

[jadams]

once you were able to "heat to win"... this "exercise" was never about replacing... at least in my mind, it was about "fixing".... I ain't got $200 for a board. Having said that, it would be terrible if you get a "replacement" and the problem still existing.... sooooo keep
"playing" and make sure the problem isn't somewhere in the connector which is a "suspect" for "thermal" stuff. Your indicated focuses are pretty good... I would certainly be "smiling" if you can find the "culprit area" and it turns out to be a $1 fix. Time I got... money I don't... and its fun learning... continued good "hunting"... oops stone rolling.

You have summed it up very accurately on all points. Glad you agree with the procedure. It helps to think like a circuit Time I got money I don't. The learning part is enjoyable and of course the challenge. When I was younger I used to rebuild engines, trans, you name it. Then they ruined it all and stuck computers in them.....now where was that stone.....

 

[OldSchoolFord]

Car-parts.com is a great sight for locating parts in nearby bone-yards. When my PCM went bad, I checked the old one after my car was running great on the rebuilt one. I couldn't see anything wrong with it. I was told to look for leaky or swelled capacitors. Use your nose for a burnt or fishy smell. Also, the bad PCM was causing all sorts of weird symptoms, similair to your problem. All you guys have alot of patients! If it was my problem, I would have freaked out along time ago and sent it to the junk-yard!! I feel you have no choise but to replace the PCM at this point. You have done all the testing a shadetree mechanic can do without expensive test equiptment. Just think of what your mechanic or local Ford dealer would charge you to replace the PCM.I have high hopes, I'm keeping my fingers crossed
Chris

 

[budwich]

one more thing that you might try for isolating things. How about only heating the connector on the cable (on my 96 its massive).... anyways.... Get it to a "no start" condition, disconnect the PCM connector / cable. "while away" from the pcm (block it with something), heat up the connector / cable.... plug it back in and see if the thing starts. hopefully it does... repeat test to confirm. That's about it for my "dream testing" last night...

 

[jadams]

.... All you guys have a lot of patients! If it was my problem, I would have freaked out along time ago and sent it to the junk-yard!! I feel you have no choice but to replace the PCM at this point. You have done all the testing a shadetree mechanic can do without expensive test equipment. Just think of what your mechanic or local Ford dealer would charge you to replace the PCM.I have high hopes, I'm keeping my fingers crossed
Chris

Hi Chris

It may have ended up in the junkyard if I hadn't just finished rebuilding the upper engine. And when I cranked it, it started on the first try and purred like a kitten. It helped that I labeled everything and documented each step. If I had taken it to a qualified mechanic or dealer I could not have afforded it, at their shop rates, don't get me wrong they earn it, but I couldn't afford it. As it is my whole investment is a lot less than the cost of the PCM alone from a dealer. Your comment about shadetree mechanics is exactly how this started out, but a couple of people in this forum use the procedures that a qualified mechanic in a good shop uses when diagnosing problems. Good critical thinking skills and as you point out....patience. Not sure which is more important.

Jim

PS. It's kind of the same thing doctors do when treating a patient. Treat the problem not the symptom. Giving someone an aspirin for a headache doesn't help much if they have a brain tumor kind of thing.

 

[doubledflooring]

If you don't mind me asking ... how much did you spend on that PCM you ordered from Cleveland? The only reason I ask is I have a junkyard near me that I called the other day to find out the pricing on it for you ... They told me 35.00 if I pulled it and 50.00 if they did. If you want I'll give you there info and you can call them.

 

[jadams]

one more thing that you might try for isolating things. How about only heating the connector on the cable (on my 96 its massive).... anyways.... Get it to a "no start" condition, disconnect the PCM connector / cable. "while away" from the pcm (block it with something), heat up the connector / cable.... plug it back in and see if the thing starts. hopefully it does... repeat test to confirm. That's about it for my "dream testing" last night...

Problem Identified.....I think

This morning the ambient temperature was 40F and when I started the car it only ran for 30 seconds approx. Tried to restart, no go.

1) Disconnected PCM, heated harness connector, reattached, no start.
2) PCM attached, rotated assembly for access to connector pin / pcb joint.
3) Placed air dam (small piece of wood) where 60 pins are. All of the other components are the other end of the board. Applied heat, it started. Repeated with same results.
4) Removed PCM, took out side, held board up to sun and looked through opposite side assuming this would make a cracked track easier to spot. Found nothing.
5) Inspected pcb/pin joints and saw what appeared rings halfway down on some pins.
6) Placed PCM in freezer hoping the lower temp would bring the suspected flaws into prominence.
7) Back outside for inspection and the suspected areas did like solder failure (is this cold solder) on quite a few more pins.

At this point I don't see the harm in trying to repair them, but there is the issue of the clear film sprayed over them. Also, What is the technique for repairing them, they look delicate? Could I actually be seeing something like the clear film causing the effect I saw. Also found a couple of solder joints that had holes in them and they corresponded to pin 1 (power) and pins 20 and 40 (grounds). Plus there were at least a half a dozen others with the ring lines around them.

What now?

Jim

 

[jadams]

If you don't mind me asking ... how much did you spend on that PCM you ordered from Cleveland? The only reason I ask is I have a junkyard near me that I called the other day to find out the pricing on it for you ... They told me 35.00 if I pulled it and 50.00 if they did. If you want I'll give you there info and you can call them.

Thanks for checking, very much appreciated
They quoted me $50, consistent with what you found, and I just discovered something else this morning. There is a number, prominently displayed, in a couple of places; POX0. This apparently has to do with calibration stuff like this (the # symbol appears to be a separator for commenting):

CLOSED_THROTTLE_SPARK_ADDER 0 # Closed Throttle spark adder (Deg BTDC)
PART_THROTTLE_SPARK_ADDER 0 # Part Throttle spark adder (Deg BTDC)
WOT_SPARK_ADDER 0 # WOT spark adder (Deg BTDC)
PIP 961 # Max PIP period
MAF_VOLTAGE 4.78523 # Max MAF voltage
INJ_DELAY 0 # Global injector delay (crank deg.)
GLOBAL_ACCEL_MULTIPLIER 0.398438 # Global Accel pump multipler
ENGINE_DISPLACEMENT 301.082 # Engine Displacement

plus a bunch of other stuff for timing advance vs RPMs, Fuel ratios for various RPMs. This is apparently what gets programmed into the eprom. Any idea if that really matters as long as the F47F-12A650-DBA is the same. Nobody asked about the POX0, including the dealer.

 

[budwich]

that's great to hear....

to help you a bit see this "picture" / article (picture isn't good but it gives you an idea... and I think from your descriptions... you are there).... http://www.tangible-technology.com/articles/joint_update.html

to fix this, you carefully reheat with a solder iron and you may also add new solder. Cold soldering is caused by improper heating causing the solder to not flow and "stick" properly along with insufficient solder to distribute the heating properly along with unclean / contaminated surfaces / solder points and poor flux. Large connectors / pins going into the boards are a "good source".

Most "DIY plumbers" have these problems with copper pipe work by not cleaning and then not fluxing and heating enough to flow the solder on / into the copper joints. A good joint should look shiny like a mirror while a poor joint will be frosted or discolored.

PS... now the $50 is sounding "good" but maybe not as maybe it bring other operational problems....... but "tiiiimmme is on my side, yes it is". ...

If it were me, my soldering iron would be hot already especially with respect to connector pins as you are not subjecting components to "over heating" if you hold thing too long... although don't burn up the board copper...

 

[jadams]

that's great to hear....

to help you a bit see this "picture" / article (picture isn't good but it gives you an idea... and I think from your descriptions... you are there).... http://www.tangible-technology.com/articles/joint_update.html

to fix this, you carefully reheat with a solder iron and you may also add new solder. Cold soldering is caused by improper heating causing the solder to not flow and "stick" properly along with insufficient solder to distribute the heating properly along with unclean / contaminated surfaces / solder points and poor flux. Large connectors / pins going into the boards are a "good source".

Most "DIY plumbers" have these problems with copper pipe work by not cleaning and then not fluxing and heating enough to flow the solder on / into the copper joints. A good joint should look shiny like a mirror while a poor joint will be frosted or discolored.

PS... now the $50 is sounding "good" but maybe not as maybe it bring other operational problems....... but "tiiiimmme is on my side, yes it is". If it were me, my soldering iron would be hot already...

I agree the $50 is sounding good, but because of the potential for those operational issues I would rather repair this one if possible. Especially with calibration code issue, but maybe that is not much, if any, of an issue.

The candidates I described look like the upper left pin. So I guess the problem is definitely identified? I also discovered some are frosted. I should use a soldering iron not gun? What about solder type? I don't know if I can add new solder because of the clear film also not sure what effect that film is going to have anyway.

Jim

Excuse me while I go plug in my soldering iron.

 

[budwich]

you are going to be an "electronics technician" by the time you are finished. Remember your "needle probe".... well get two straight pin probes (black and red / plus and minus). Set your meter on Ohms... start checking things for continuity pass / thru the troubled area. ... ie stick one end on a good part of the connector (where the pins grab the plug) then visibly trace the track pass the "problem area" to a component point / wire leg, etc... somewhere you might have good access / contact... "stick it" with your other probe. Hopefully, you should see a "short".. ie 0 ohms. If you don't then, this is a good area to focus your "repair effort" on resoldering. Of course, this is bench testing not when it is on your vehicle and powered. From your initial "diagnosis" it sounds like you have a few areas but not too many. Note: I think that the board might be doubled sided ... that is circuit tracks on both sides but I don't know... just what I read.... doesn't mean much but you have to careful do you tracing when you are trying to follow a given track.

 

[jadams]

you are going to be an "electronics technician" by the time you are finished. Remember your "needle probe".... well get two straight pin probes (black and red / plus and minus). Set your meter on Ohms... start checking things for continuity pass / thru the troubled area. ... ie stick one end on a good part of the connector (where the pins grab the plug) then visibly trace the track pass the "problem area" to a component point / wire leg, etc... somewhere you might have good access / contact... "stick it" with your other probe. Hopefully, you should see a "short".. ie 0 ohms. If you don't then, this is a good area to focus your "repair effort" on resoldering. Of course, this is bench testing not when it is on your vehicle and powered. From your initial "diagnosis" it sounds like you have a few areas but not too many. Note: I think that the board might be doubled sided ... that is circuit tracks on both sides but I don't know... just what I read.... doesn't mean much but you have to careful do you tracing when you are trying to follow a given track.

The circuits are double sided. I can't access the ones on top at the pcb/pin joints just the ones on the bottom. But I do know the location of the ones associated with the PIP circuit and the grounds, there are 4 of those, also the ones that are on the CMP/CKP/ICM loop.

Just returned from inspecting PCM after sticking it in the freezer for a much longer time. Many more pcb/pin cold solder areas than I found previously. Then heated it up, just to room temperature, and they were not so obvious. I can't even see them under my shop magnifier I have to use the 8X Lupe.

What about the film covering everything? I have the soldering iron out and ready to go.

 

[budwich]

The "surgery" will involve "gentle scraping" with an blade of some sort... box cutter, that sort of thing. But I would try and do the measuring thing to see if I can find a specific "no continuity" track/area .... it will hopefully cut down the amount of resoldering you have to do. Depending on what the film is... if it is really hard and thin, then the blade will kind of scrape / shave it off... if it is really thick, my "friend" is a dremel but then the "surgery" is up the scale to "brain surgery type" effort cause one "slip" and you may cause a major board / track problem (leave the dremel as the last resort)..... but it is soft /rubbery, then you might have to cut thru it a bit / carefully to expose some copper. Magnifying glass is your friend.

An iron is better than a gun (weller I assume)... because the iron stays hot well a gun turns on (and off with use) and usually has a larger tip. In terms of solder, "standard" lead based ones are used in electronics... they usually don't have an acid core (flux) as this will cause problems in the future... if you can use rosin core ... BUT I have used various ones without issues. Home Depot... Radio Shack... I don't know what you out your way... but if you have some from plumbing... that will work no problem... the paste flux will also work.

The film will probably be a problem but try heating it with the iron and see if it "burns" away or gets "crisp" enough to readily scrape.

 

[jadams]

But I would try and do the measuring thing to see if I can find a specific "no continuity" track/area .... it will hopefully cut down the amount of resoldering you have to do.

I had 24 cold solder out of 60 pcb/pin. I was able to reheat most and get them to flow out. That film is a real problem plus I can't access the top at all. There is about 3/16" between the input pcb/pins connection. I don't know about using a Dremel unless I was using a tiny 3M flap wheel maybe. But some of those circuit tracks are very thin.

By the way, stuck it back in the car and same problem, but again I reheated about half the pcb/pins and only from the bottom. And not completely sure I'm doing this right, 50/50 maybe.

 

[budwich]

don't forget to try and do the continuity measurement stuff from the connector pin to the first component on the track. as for the dremel... the bits that I use are small carving bits... similar to what they use on your teeth for fillings... just lightly buzz stuff "slowly" off. but very carefully. I am disappointed that your 24 out of 60 didn't help.

 

[jadams]

don't forget to try and do the continuity measurement stuff from the connector pin to the first component on the track. as for the dremel... the bits that I use are small carving bits... similar to what they use on your teeth for fillings... just lightly buzz stuff "slowly" off. but very carefully. I am disappointed that your 24 out of 60 didn't help.

Speaking of lightly buzzing, I have the DVOM set to the most sensitive and buzzer icon and I'm readings from .564 to 1.978 Ohms when testing components and when I test a track I get a buzzer. Is this correct? I tested connector pin to the board for continuity and they all checked OK, next step continuity to component?

Since I can't get to the top....

All is not lost I'm going to take some HiRes images and start tracing visually, then do continuity checks on the board. My magnifier is OK for most general work and the 8X Lupe is only good for an area about the size of a 35mm film slide. So I'm going to a macro shoot the front and back and work from that using the schematics I have. However, the EEC IV schematic is kinda poor quality and doesn't show output circuits, like the injectors, so I'm having to trace them and make notations on my jpgs, this is a little on the tedious side. But given the desired results I ffel it will be worth the effort.

As far as the soldering on the pin/pcb connections I have small Dremel attachment I'm going to use to try cleaning the connections better.