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Discussion Starter #42 (Edited)
It is the ICM that needs to be Black and not the PIP sensor.
You have said the the fuel pumps were running in some of the post above are you saying that the fuel pumps run all the time the key is in the run position with the engine not running?
If yes then yes you do have a bad PCM.
Subford, let me respond and try to summarize:
I don't think fuel pumps are running all the time but I certainly hear them build pressure at startup and I have pressure tested at the rail, both key on and running, as well as power braking to simulate load and pressure was nominal. All this with MAF disconnected. After driving truck for 10-15 minutes, I can replug in MAF and no change. But if I turn off the engine and try to restart, it dies immediately.

Basic problem is that truck died while driving and engine now dies immediately after strong start. No response to throttle as it dies. I happened to disconnect MAF and engine started and ran - it runs poorly at idle but pulls fairly well under power. Replaced MAF, same result. Codes were only for Bank 2 sensor 1 lean and of course for low flow at MAF (disconnected). With MAF plugged in , I can't get it to run long enough for testing. During dozens of starts and stops, it threw one code (P0320 if i recall correctly) that indicated PIP and you mentioned your experience indicated to replace even after one code - thus I'm sourcing a motorcraft new distributor.

I have replaced TPS, fuel filter (which was relatively clean), both upstream O2 sensors, and the fuel pressure regulator. I have two fuel tanks and while running with MAF disconnected, I can switch tanks with no change in performance.

My theory is that a air\fuel related sensor is failing at start and killing engine by either shutting off fuel or air - I'm guessing fuel given zero throttle response as it dies. I suppose it could also be spark but it happen too fast to tell. I'm unable to get it to run long enough to generate a code. I'm assuming engine goes in to limp mode with MAF disconnected and thus I'm able to start and drive - albeit with poor performance.

I removed and inspected the 1 yr old replacement PCM - no blown or leaking capacitors, but some minimal evidence of water intrusion on the bottom\outside of the PCM casing. No evidence on the inside. The PCM was replaced a year ago for a CEL (Bank2 Sensor 1 lean code) and the CEL returned not too long afterwards.

I've sprayed all injectors while running to check for leaks with no change in RPM. I also watched fuel pressure over a period of 15 minutes with key on and pressure remained constant.

I've used compressed air to clean out the inside of the distributor with no change. The rotor and cap were replaced in the last couple of years and show minimal wear.

Any suggestions on how to test to identify the fault?
 

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The only thing I can think of at the moment is I heard of a similar case a few years ago and the problem was the PSOM. It was giving an over speed while the truck standing still and the PCM was shutting the engine off at start up.
You can try unplugging the PSOM and see what happens. This will make the transmission shift hard but we want to see how the engine runs with it unplugged.

This was mentioned above. Look over the Ignition switch and its plug as it can also cause a similar problems to your case. We are not talking about the tumbler but the switch down low on top of the column.

Also check the voltage coming from the TPS. It should be 0.90 to 1.0 volts at closed throttle and around 4.8 volts at WOT. It is best to check with an analog VOM so you can watch the needle move smooth with no jerks as you open the throttle.
 

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Discussion Starter #44
The only thing I can think of at the moment is I heard of a similar case a few years ago and the problem was the PSOM. It was giving an over speed while the truck standing still and the PCM was shutting the engine off at start up.
You can try unplugging the PSOM and see what happens. This will make the transmission shift hard but we want to see how the engine runs with it unplugged.

This was mentioned above. Look over the Ignition switch and its plug as it can also cause a similar problems to your case. We are not talking about the tumbler but the switch down low on top of the column.

Also check the voltage coming from the TPS. It should be 0.90 to 1.0 volts at closed throttle and around 4.8 volts at WOT. It is best to check with an analog VOM so you can watch the needle move smooth with no jerks as you open the throttle.
Thank you. I wasn't sure what the PSOM was but looked it up.

I went ahead and replaced the ignition switch and tumbler as I had already picked up spares. No change in start\die problem.

I will test the TPS voltage, but I will also check my running tests via Torque or Forscan as I believe I have recorded live data that showed TPS voltage while running with MAF unplugged. I'll check with an analog VOM in the daylight tomorrow.
 

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Discussion Starter #45
subford, I checked the TPS voltage, and engaged a Ford specialist to help with confirming ground connections and voltages across a variety of points. All good.

Using a SnapOn scanner as well as a full diagnostics machine, we found the PCM thought that the truck was at 4000ft elevation and would not accept any flash programming (hope I"m quoting him correctly). Bank 2 was maximum lean versus Bank 1 was maximum rich with all 3 O2 sensors performing and responding.

So our working assumption is fried PCM, despite no evidence of damage when I inspected several days ago. I've got one on order from Flagship One and will update upon arrival and further testing.
 

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subford, I checked the TPS voltage, and engaged a Ford specialist to help with confirming ground connections and voltages across a variety of points. All good.

Using a SnapOn scanner as well as a full diagnostics machine, we found the PCM thought that the truck was at 4000ft elevation and would not accept any flash programming (hope I"m quoting him correctly). Bank 2 was maximum lean versus Bank 1 was maximum rich with all 3 O2 sensors performing and responding.

So our working assumption is fried PCM, despite no evidence of damage when I inspected several days ago. I've got one on order from Flagship One and will update upon arrival and further testing.
If it won't accept any flash programming, that is a problem. Did your Ford specialist tell you what calibration was in the PCM at the moment? It should have been a readout on his scanner.

On these trucks with a MAF sensor, there is no pressure sensor (unlike the non-California Speed Density trucks, and so the Barometric pressure is inferred from the MAF readings. So the notion that the PCM thinks the truck is at 4000ft, just means that the MAF reading is bad, but not bad enough to set a MAF code when the MAF is plugged in. It won't be any less frustrating for you, but your PCM might not be be the cause of the problem (even though you should have one which you can reflash. So I hope you can return the new PCM if it doesn't make any difference.

I'm now suspecting your previous PCM might not be as good as it should have been, (and may not have been the correct calibration for your truck), or there may be a wiring issue between the MAF sensor and the PSM, and also possibly between the PCM and the OBD2 socket (as that could stop the PCM from reflashing.

Did you and your specialist run the MAF test that I posted a link to, the one with the multimeter on the MAF pins?
 

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Discussion Starter #50
I wasn't in the shop for part of the time and missed some of the process. I had replaced the MAF at the start of this process and then had put the original back in given my results. He opened the original, as well as tested voltage, and found that it was dirty (I got a C- in MAF cleaning) but checked out OK. We ultimately put the new one back in since I couldn't return it. No change. He did trace the wiring for the MAF and checked both voltage and grounds, as well as voltage and grounds for the PCM and TPS. All checked out but there was one volt reading that I wasn't familiar with that he noted was lower than normal - I'm waiting on the PCM from Flagship One and headed back to his shop when it arrives - I'll update on what he was referring to.

While I was away, he attempted to flash the PCM, he noted it thought it was at 4K ft., but would not accept programming. I don't know if that was inferred from the readings by the Snapon tool or if he made a mistake.

I had noted that the PCM ground wire, connected to the inner fender well above the ICM, was positioned in such a way that it made a perfect water conduit for rain - which I observed running down the wire, into the plastic harness cover and into the PCM harness connector and then dripping out of the bottom of the PCM connector. I re-positioned it, used a blow dryer on the PCM connector and looked for evidence of corrosion but found none. That still freaks me out but I found nothing.

The original PCM was replaced a year ago, in response to a persistent CEL from IIRC a Bank 2 lean code. We also replaced and re-installed both upstream O2 sensors. I spent a small fortune on the mechanic at that time who spent hours with a test light. The truck ultimately ran fine with the new PCM and smogged but the CEL came back a few months later. Since it still ran fairly well ( i ignored mileage), I left it alone and turned up the radio. It's entirely possible the current PCM was flashed wrong for my truck\location\California requirements, but I would have thought that it would have failed smog if that were the case. That level of understanding is above my pay grade.

When the new PCM arrives, I'll remove the current and re-check wiring as well as note the lettering on the unit and respond back. I doubt it is returnable.

I did watch the video but did not have a chance to execute the testing as my friend had offered a couple of hours of diagnosis. mpaton it was a great instructional video, so I will circle back and do the testing with the original MAF installed this weekend but the rubber will meet the road when the PCM arrives and is installed.

I have no doubt this isn't over and there is at least one other issue contributing to the start\die issue. My wife reminded me that the truck has died twice in the last couple of years and not restarted until having sat for 20-30 minutes - which points me back to the distributor and ICM and CPS as secondary issues.
 

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I have no doubt this isn't over and there is at least one other issue contributing to the start\die issue. My wife reminded me that the truck has died twice in the last couple of years and not restarted until having sat for 20-30 minutes - which points me back to the distributor and ICM and CPS as secondary issues.
Yes, you've had quite a struggle with this one, and it's still not over. I don't know if you've sent the old PCM back yet, but if your specialist can read the code out of it, I may be able to tell you if it's the correct one. Same for the new one. And it may be that the new one has some labels on it.
Like this one from ebay,

https://www.ebay.com/itm/AS-IS-1996-FORD-F250-F350-460-7-5L-E40D-ECM-F6TF-12A650-BSA-ECU-PCM-AS-IS/183676975904?hash=item2ac4003b20:g:x6kAAOSwwfFcNoIO

This has the code BCC0 The ebay one is an EEC-IV, but the label arrangement is the same.

Your symptoms of dying and staying dead or 20 minutes also match an overheating fuel pump.
 

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Also if the calibration sticker is still there, it could be useful, it will tell you what PCM was in it when new.

If you go the the back side of the driver's door, there are 2 decals on the back edge, just above the throat of the lock. The uper one is about 3" wide by 2.5" high and has the VIN on it, and axle data and more.

Immediately below it, and a little to the left is a decal that is about 2" wide and 7/8" high, and on the top left of the decal it says CALIBRATION and in the bottom left it has a code, similar to 6-98Q which is what's on my 460 Cali spec truck. If you find it, post it.
 

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Discussion Starter #53 (Edited)
Yes, you've had quite a struggle with this one, and it's still not over. I don't know if you've sent the old PCM back yet, but if your specialist can read the code out of it, I may be able to tell you if it's the correct one. Same for the new one. And it may be that the new one has some labels on it.
Like this one from ebay,

https://www.ebay.com/itm/AS-IS-1996-FORD-F250-F350-460-7-5L-E40D-ECM-F6TF-12A650-BSA-ECU-PCM-AS-IS/183676975904?hash=item2ac4003b20:g:x6kAAOSwwfFcNoIO

This has the code BCC0 The ebay one is an EEC-IV, but the label arrangement is the same.

Your symptoms of dying and staying dead or 20 minutes also match an overheating fuel pump.
This current PCM was purchased and programmed by CarId and I mailed my original back for core. I've ordered a remanufactured one from Flagship One and they have screwed around for 8 days, telling me the first one they programmed failed testing and it will be another "few days". Called yesterday and got more vague answers on when it will ship.

My NAPA source says they have one in their warehouse in Los Angeles and can flash it and have it here in two days. The coding on my PCM is ML1-441 and that matches up to my VIN as best I can tell. I'm going to try to cancel Flagship One today and order through NAPA with the expectation that I can try it and return it if necessary.

I hear you on the fuel pump, but I have dual tanks thus two pumps. The start\die symptom is consistent after switching between tanks AND fuel pressure is solid when engine running without MAF with no hesitation under any throttle. I think that eliminates fuel pump failure as the current issue but agree with you that the occasional die and no start could be fuel pump failure. I'm sure I'll fix one thing and then find one or two more. Good news is I've already replaced a bunch of other parts so maybe that will stave off future failures:wink:.

Progress......
 

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Any PCM that's going to work on your truck would have to say ML-441, but that isn't the whole story. That number is just the hardware that's inside the PCM, and says little about the software that's flashed into it.

Does your truck still have the calibration sticker I mentioned in post #52 ?

And on fuel pumps, I'm absolutely NOT saying replace any fuel pumps. I just don't think the symptoms point definitively to PIP sensor and away from Fuel pumps.
 

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Discussion Starter #55
Also if the calibration sticker is still there, it could be useful, it will tell you what PCM was in it when new.

If you go the the back side of the driver's door, there are 2 decals on the back edge, just above the throat of the lock. The uper one is about 3" wide by 2.5" high and has the VIN on it, and axle data and more.

Immediately below it, and a little to the left is a decal that is about 2" wide and 7/8" high, and on the top left of the decal it says CALIBRATION and in the bottom left it has a code, similar to 6-98Q which is what's on my 460 Cali spec truck. If you find it, post it.
Got it. Calibration (or Etalonnage as they say in Canadian French apparently!) is 6-98Q-R10 F6AE-6E061-BYD
 

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OK, well that's a bit interesting, as that's the same code as mine, and my truck is a 97 model year. My information had been that the 96MY California trucks had a thermactor air pump, and the 97 MY didn't, with an idler pulley in its place so they didn't have to spec a new belt.

Either way, the software "Catch Code" that would have been on the truck when new would have been "FEZ2", which was superseded by "FEZ3". So you ought to be getting a FEZ3 in your new PCM. Assuming it's a 4WD
 

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Discussion Starter #58
OK, well that's a bit interesting, as that's the same code as mine, and my truck is a 97 model year. My information had been that the 96MY California trucks had a thermactor air pump, and the 97 MY didn't, with an idler pulley in its place so they didn't have to spec a new belt.

Either way, the software "Catch Code" that would have been on the truck when new would have been "FEZ2", which was superseded by "FEZ3". So you ought to be getting a FEZ3 in your new PCM.
Can you take a picture of where the idler pulley is and I'll confirm if I have a thermactor air pump. I have no records from the previous owner so no clue if any changes of this type were made. If I recall, you indicated that the FEZ2 would be imprinted in big letters on the PCM? If so, when I get the new one and pull the existing out, I'll check and post to confirm.
 

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The thermactor or idler pulley would be on the passenger side of the engine directly below the alternator, driven by the same belt.
 

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Discussion Starter #60
The thermactor or idler pulley would be on the passenger side of the engine directly below the alternator, driven by the same belt.
Looks like I have an idler pulley and not a thermactor pump. I attached a couple of photos - it's pouring rain so forgive the quality.
 

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