1994 Ford F150 5.0 auto w/E4OD 4x4
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Not sure if it is a PCM issue or not.
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Abridged version of problem at end
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Driving fine, I was coming to a stop sign and it stalled. If would not crank.(I had a similar issue not long ago with the pip sensor. I replace the dizzy and it has work fine for 2 months.) I tried to crank it a few times and it finally turned over running rough. It went into limp mode. I was able to get it home. I tried to start it again and the fuel pump kept running instead of a few second prime. It did this on front and back fuel tank. I tried to pull codes with my scanner, it would not pull a code at all. I ran some errands with the wife and came back about 3 hours later. It started fine runs fine and the fuel pumps are working correctly. I tried to pull the codes and it comes back as PASS or 111.
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Doing some research it points to the PCM. What do you guys think? Can the PCM be intermittent ? I went to advance auto parts and they said i can get one in 24 hours for $165. Before I go buying a part I wanted to see what you guys thought.
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1. car started fine
2. Stalled at stop sign
3. would not crank
4. pushed out of road
5. Tried to crank it a few times it finally turned over and ran rough (limp mode)
6. got it home
7. tried to pull a code, scanner would not pull any codes
8. fuel pump constantly running
9. left to run errands for 3 hours
10. came home, it started right up like nothing happened
11. ran codes everything clear 111
12. fuel pump works normally now
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HELP????

 

I would start with your dizzy if that was the last thing you changed before all of this.

 

I get a sense of "crank" and "turn over" being used to say something they do not really mean.

Does the starter engage and rotate the engine's crankshaft when you turn the key? That would be the usual meaning of crank and turn over.

Does the engine fire and continue to run after the starter has been engaged? Desireable outcome, but this is not what is typically meant by crank and turn over. More accurately, this is described by saying the engine is running, although the engine may be running well, or not.

At any rate, cranking the engine has nothing to do with the PCM. Cranking circuits are simply the battery, solenoid and starter motor along with the primary cables. Cranking is controlled by a battery circuit from the ignition switch which has been physically engaged with the key.

Of course, all this has to be in the context of our old trucks. Bring new technology with vehicle antitheft systems present in the PCM and you will quickly call me a liar, but that just is not relevant here.

So, please excuse my confusion here, but is what you are saying that your truck is hard to get running because it will crank, but not fire and run, possibly intermittantly?

 

I was advised that one sign of a PCM possibly going bad is the inability to pull codes, reader failing to communicate with the PCM. You may want to pull your PCM and inspect the board for discrepancies. I also thought that abnormal fuel pump behavior could also be attributed to a PCM going bad. Still, you could have an intermittent wiring concern. I am sure someone out there can give you a better answer/advice. Looking forward to hearing about the fix for this topic.

 

I wouldn't waste any more time and inspect the ECU. Mine had interment issues for a couple of years before pulling the ECU and finding a lead corroded off one of the caps. Go pull the ECU and inspect it.

 

Agreed!

Don't waste anymore time on inspecting the PCM.

 

Here are some photos of the PCM. The brown spot is that leaking? Is that my issue?

 

 

The brown spot could be capacitor fluid. It's hard to tell, but it looks like there may be corrosion near the capacitor terminal.

 

Mine looked similar. You can see my pics on post slow start/poor starting. I just replaced my capacitors but haven't tested it in the truck yet.

 

I would say that is a bad capacitor. Replacing it may or may not fix your problem.
That capacitor is the filter for the incoming power.

What numbers does the PCM plug have on it?
In other words is that a rebuilt PCM? I ask this because that is the second photo of a PCM with surface mount capacitor filters I have seen on here in the last month and none in all the years before in this forum.

 

 

I noticed that too about the surface mounted caps.

I wonder what Ford was thinking....

 

Just guessing but maybe that (those) PCM computers were sent off for repair and the repair place just cut off the radial capacitor pins flush with the board. Then took a shortcut and replaced the capacitor(s) with surface mounted capacitor(s) in lieu of sucking out the solder as a short cut.

If this is the case then the brown on the board in the above photos may be from the old capacitors that were on the board before and leaked.

 

Got a couple theories. SMT becomes an economical way to build circuit boards and cost control is the reason any manufacturer makes a change. What is surprising here is that Ford did this so late in the product's life span.

I noticed the ECU in this thread is from 1994 and the one in the other thread that subford mentions is from 1995. OBDII was mandated for 1996 and I believe EECV was the first use of the new protocol for Ford. I recall Ford had some sort of exemption for the 1996 OBS trucks which also carried into 1997 with the F250HD and F350. Exception for California and that is the only reason you see OBDII in these vehicles. Now, I have never seen an OBDII equipped OBS truck in my neck of Canuckistan, but since they do exist, could anyone verify if they are EECIV or EECV? I know the V8 Explorers with the 5.0 were EECV. And sorry for the .

SMT requires a different circuit board than does wire lead components like the capacitors typically seen, so Ford must have engineered a new circuit board in the mid 90's. I'm pretty sure the cost savings alone for using the SMT electrolytic capacitors may not be sufficient to warrant this. Perhaps there was some consideration for developing OBDII within the EECIV platform? I have an EECIV ECU from a 4.6 modular engine that used OBD1 and incorporates MAF and EDIS. I have read somewhere that there is increased processing power in the later EECIV ECU's and perhaps the redesigned board also accommodated this?

Back on track for this thread, changing SMT caps requires some pretty delicate soldering. The components were typically glued to the circuit board and wave soldered. It is possible to change them with more conventional tools, but it requires a steady hand and a good soldering pencil. A temperature controlled station with a fine tip is probably the minimum you should be using here and cleanliness is essential. Remove the flux when you are finished! I repaired electronic equipment from the 70's through Y2K. It has been some time since I have had my hand in this, but I can say that it has been done successfully.