Ok, just a quick summary. This is a 1998 F-150 with the 4.6L Vin 6 engine with 235000 mi and auto trans .
Recently my tuck has been stalling at an absolute random pattern. When its hot or cold, driving or parked, while braking or while accelerating and even at steady speeds. No chugging or surging just dies like someone turned off the ignition switch.All electrical power good, turn key off for 3-5 seconds and it starts right back up, sometimes for hours sometimes it stall again in a few minutes.
Other than this it drives like a new truck.
Recent attempts to fix this are:
Fuel pump assembly (pressure was good, just sounded rough)
Fuel tank (inc.. hoses, sensors)
Fuel filter
PCV valve
Egr tube (rotten so may as well)
Crank position sensor
Cam position sensor

This was all done on the last 2 weeks and the problem is still here.

Recent maintenance done about 45-60 days ago.
Plugs
Wires
Pass side coil (it was cracked but functioning fine)
Alternator
Starter


My mechanical ability is extensive, just not on my own cars. I usually over-analyze my own cars so any thoughts or problem solving help would be appreciated.
Scan tool give no codes and live data did not reveal any areas of interest. Although I went old school and ran a prog thru my laptop that gave me mode 6 data and I found two tests failed:

Test ID 41 component id 11 Fail
Egr systems monitor
Upstream hose disconnected

All hoses are tight and leak free, But emissions wouldn't cause a stall..... EGR system fail wouldn't be a stall like this, it would run rough, stumble, then die.... Right?

AND
Test 00 cid 52
Consecutive cylinder events durring active tests.


But apparently not enough to get a fault code, Ever????

 

If you can read Mode 6 data, are you able to acquire cylinder history ? Like say, a misfire count below and above 1000 rpms ?

It could be a few things. A bad connection/ battery/alternator. A hanging EGR valve will kill the engine, but from your description, I don't think that's the problem.
Yea, - your going to have to go thru it.

Bad connection. They will stall without battery power.

Harness connectors , specially at the CPS sensor.

Wiring, open /bad ground. Go thru all grounds, PCM, firewall and interior kick panels. One under pass side cab.

The PCM may be acting up. Really hard to say without going over it.

 

I have tested the EGR, ground connections, positive connections, all sensor harnesses in tact and no corrosion on connections. Only things I can think of would be the coil or PCM, I have the two coil system,Driver side is OE and the passanger side was replaced recently with a Borg Warner. If I remember correctly the ignition control is in these packs not in the PCM right?
How does one identify the PCM as the problem with the issue being so random? While the scantool is connected I drove around for about 40 miles and no sensors showing out of range and when it stalls all data looks as if all is well.
I hate throwing parts at it, but even the dealer wont figure this out,not to say they are stupid, but I have a decent handle on diag.
I have the Ford publications program for the truck and I followed it to a T and all it did was make the wallet much lighter. So Ford would be doing the same but with all the labor on top...


So what is more likely to be bad, the driver side coil or the PCM? Keep in mind it runs, drives ,idles like a brand new truck. Until it stalls that is....

 

A coil pack wouldn't cause a stall, not like you describe. Bad connection IMO. So you checked all big cable grounds ? You check the one on the frame rail behind the tire ? You check the big engine ground under the engine by the starter ? What absolute ground ? That's the matting surfaces , -alternator/engine block ?

Oh wait a minute.. You have MEGA fuses on that model right ? Two 175's I believe. Those are notorious for this type of stall, (intermittent). Yea, I bet its cracked inside. What happens is they crack @ solder ball inside the casing, - you can't see this. These fuses also cannot be bent, not even a little. They break very easily inside. They discontinued this fuse in the 99 models.

BTW- Continuity tests will not necessarily show this fuse as bad when it is indeed bad. That's because of the way go out or break inside.

 

Also, upon restart, - you can only crank these engines for 4 seconds. After 4 seconds the PCM shuts the injectors down.

Keep that in mind when attempting restart.

 

Ill replace those 175A's and check that ground on the frame. Worth a try. When I do have to restart it will not unless I turn key off for a few sec then it fires right up. Also, this does not always happen but I noticed when it stalls at idle in park sometimes after the stall the fuel pump keeps going as if it does not know the engine stalled. It did that with the old pump and the new. But pressure is good, no drops. I am 99% certain that it is ignition related. I hope its not the PCM, that requires a hefty dealer charge for a paramater reset if I am not mistaken. Ill post results after I replace the 175a fuses and remove /clean all grounds again. I thought I got them all but cost nothing to do a second check.

 

Well, ****. After all that it appears that the damn 175A fuses may have been the issue! Makes sense but would have never thought if not for JBREW. Good call dude!
I have 100 miles on and no stalls yet.

 

Hopefully you got it fixed!

 

Yea, those 175's will mess with your head. I've had to go as far as bi-passing them before, temporarily, -in order to determine.

I have a write up I did on them somewhere, can't locate it. Found a pic from it tho, in one of my old gallery's on this site. -



Glad you got it fixed.

 

New Update****
Its stalling again, same as before. But now it will not restart right away. It just turns over without a fire. Fuel at normal pressure. I did unplug the IAC and then it started, so I am replacing the IAC tonight and I will update. When it stalls the fuel pump keeps going until I turn off the key. Whats that all about?

 

Not sure if you changed this but a bad CID sensor can give intermitten starts. A defective one will prevent starts about 50% of the time. check your HDR sensor connection and wire it is located behind the A/C compressor on the side of the front cover.Sometimes the HDR wire will rub on the serpentine belt and wear thru. Also excessive crankshaft endplay can cause no start or shutdown while accelerating as the crank moves to far and the HDR pickup loses contact with the HDR sensor,rare but can happen. Good luck.

 

The camshaft and crankshaft position sensors were replaced in this chase already. Better Idle from it but was not the fix. I just hope its not the ECM, sounds like a PITA to get it programmed.

 

Sorry I was chasing my grandson around the house and didn't take time to read the list of items you already changed. I just threw out some ideas my mistake.

 

Check the battery under load or throw a different one in from another car whatever. If you are momentarly losing sufficent voltage from the battery your PCM/ECM can malfunction and shut you down.

 

Well, new IAC installed, ran it for 20 minutes or so and no stall. Then I turn it off and take the key out, wait 30 seconds and put the key back in at tried to start it. It would not start, and a clicking noise coming from either the relay box, or what I assume is the BCM next to it. Turns over , fuel pump running continuously but no fire. Not the fuel pump as previously covered, along with that shiny new gas tank....... So I take the key out, walk away in absolute frustration to bang something good with a wrench to show something I am the HMIC. Come back 3 minutes later and wah-laa, fires right up and purrs like I just bought it. Ran it for another 15 minutes, turned it off and then tried to start and it wouldn't. This time no clicking noise from front as before, only the fuel pump continuously running until I turned the key off. Waited 45 seconds and it starts up just fine.WTF?
I tested the battery with accy load on and off and no failure with the power sources. I even rotated the relays to see if I had a bad relay, the relays do not seem to be the problem either.
Can someone explain the PATS system to me? I am not certain if I even have factory security or even if it could be an issue like this. It does seem like the ignition has a failure or had been disabled yet it still cranks over (unlike something with a starter disabling system would do) and the fuel pump has ran continuously during some of these " I don't want to start" tantrums this truck has had recently. That seems like a completely different level of WTF for me. Why would the fuel pump run continuously without the engine running and not have a pressure or fuel system related issue?

Any words of encouragement?