Engine control weirdness.

raydav

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2001 E350 cutaway

Last weekend we went to the Hot Rod Reunion. It takes place mostly at Fomosa drag strip, but the Friday evening event is in Bakersfield. Bakersfield is about 150 miles from home.

Friday evening, we were in Bakersfield, had made a few stops, and were heading for the evening event. I leaned on it up an on ramp, it started to pull, and then went to mush. It felt like I lost half the engine, and I had a check engine light.

We limped to the event, found a good street light at the back of a parking light. I shut off the engine, plugged in the laptop, cleared the fault log, and started the engine to get a fresh fault list. The engine ran normal, and there was no check engine light. So I shut of the engine and ran an engine off check, them started and ran an engine on check. Both checked OK.

So I figured a computer glitch which a reboot fixed. I put it in reverse, it backed OK. I put it in drive, and the engine stopped. I did that three times.

I swapped the power train controller and all was well. We drove out to Fomosa, moved the vehicle several times, and on Sunday headed home. We got up the mountains fine, and just past the top, on level ground, had a repeat of Friday evening.

I remembered Friday evening, was concerned that something was blowing power train controllers, and was afraid that if I stopped it might not move forward. So we limped about fifty miles to a Pilot Station.

I parked, shut off, and restarted. It ran OK and no check engine light. It also moved forward OK. I recalled from Friday evening when I cleared the fault log there was a vague "injector fault noted". So I swapped the injector driver. We then drove the fifty miles home without incident.

Does this sound familiar to anyone?
 

79jasper

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Never clear the codes without checking them to get a "clean slate."
I would bet you have a issue with the UVCH.

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raydav

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Never clear the codes without checking them to get a "clean slate."
I would bet you have a issue with the UVCH.

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I am not looking at codes. The fault log is text. And the clear button is on the same page, so I would always see what I was clearing.

As for UVCH, been there. That is why a couple years ago I reworked that area including safety wiring the under cover connector.
 

raydav

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That's typically the UVCH.
You already tried swapping the pcm and idm. That leaves wiring.
Let me get you a test diagram.
http://www.gbreman.com/articles/?p=242

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Reread the original post. It faulted, shutting off and restarting made the engine OK, but it would not move forward. I swapped the PCM, is was OK, for a while. It faulted again, shutting off and restarting made the engine OK, and it would move forward. It seemed OK but I swapped the IDM because there had been an IDM fault logged - that entry did not identify the fault. There has been no further issue.

There are four injectors on each bank. An intermittent under the cover is not going to break and make all four together. And shutting off the engine and restarting is not going to fix an under cover issue.

The only problems that are fixed by rebooting the computer are computer problems. Is there some "feature" that if the PCM has or detects a certain condition, and you attempt to drive forward, it shuts off the engine?

The currently installed PCM and IDM on-board test clean. The PCM I replaced has a keep alive error. I have seen that before but I have never lost half the engine before. An IDM I previously replaced and the IDM I just replaced on the road both report #3 low. Note, not 1,3,5,7, just 3. And I shut down the diagnostic program while I changed units. But I still think that is a huge coincidence.

I have lost one injector due to an under cover intermittent that became a permanent open. It ran a little rough and I had an engine light. But I could still keep up with traffic.

And the schematic shows a two piece connector. So, I see a connector on the outside, but was unaware there is another connector on the inside.
 

79jasper

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Reread the original post. It faulted, shutting off and restarting made the engine OK, but it would not move forward. I swapped the PCM, is was OK, for a while. It faulted again, shutting off and restarting made the engine OK, and it would move forward. It seemed OK but I swapped the IDM because there had been an IDM fault logged - that entry did not identify the fault. There has been no further issue.

There are four injectors on each bank. An intermittent under the cover is not going to break and make all four together. And shutting off the engine and restarting is not going to fix an under cover issue.

WRONG Only takes one injector to shut down a hole bank. Typically a short to ground. Which could be from wiring, or a bad injector solenoid.

The only problems that are fixed by rebooting the computer are computer problems. Is there some "feature" that if the PCM has or detects a certain condition, and you attempt to drive forward, it shuts off the engine?

No.

The currently installed PCM and IDM on-board test clean. The PCM I replaced has a keep alive error. I have seen that before but I have never lost half the engine before. An IDM I previously replaced and the IDM I just replaced on the road both report #3 low. Note, not 1,3,5,7, just 3. And I shut down the diagnostic program while I changed units. But I still think that is a huge coincidence.

I have lost one injector due to an under cover intermittent that became a permanent open. It ran a little rough and I had an engine light. But I could still keep up with traffic.

That's losing a injector. Doesn't mean it shut that bank down.

And the schematic shows a two piece connector. So, I see a connector on the outside, but was unaware there is another connector on the inside.



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snicklas

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I'm not saying that's exactly what this is, but I have seen shorts to ground be long enough to trigger the computer and shut it what ever it's controlling down. Power cycle and everything works until it shorts again. Sometimes it's from a vibration, and the stop and start moves the short enough to not short......
 

raydav

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I'm not saying that's exactly what this is, but I have seen shorts to ground be long enough to trigger the computer and shut it what ever it's controlling down. Power cycle and everything works until it shorts again. Sometimes it's from a vibration, and the stop and start moves the short enough to not short......

The wiring in the PCM area is very busy. But I will have a look. It will have to wait till after SEMA next week.
 

OLDBULL8

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It is a very common thing for the harness that lays on top of the valve cover on the drivers side to wear thru the insulation causing wires to short out, that can be intermittent or solid.
Sounds to me that's where your problem is, put a piece of something under the harness that will insulate it from the cover, see if that fixes the problem. The bare wires can touch each other also, the engine vibration can make shorts come and go.
 
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raydav

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It is a very common thing for the harness that lays on top of the valve cover on the drivers side to wear thru the insulation causing wires to short out, that can be intermittent or solid.
Sounds to me that's where your problem is, put a piece of something under the harness that will insulate it from the cover, see if that fixes the problem. The bare wires can touch each other also, the engine vibration can make shorts come and go.

A couple years ago, while on the road, I had one passenger side injector go intermittent then open because of the underside connector. The schematic shows a two piece connector, I could see a connector on the outside, spent time on that not knowing about the inside connector. A Ford dealer fixed it well enough to get me home. It is a van, so working that area is no fun.

After I got home I removed the engine harness, un-bundled it, and added an eight inch pigtail to the valve cover wires, and re-bundled it different than Ford had it. I can now pull the valve cover sections of the harness out the front.

And I safety wired the the under cover connector. No I didn't stick quarters in the connectors. But I did insert a piece of unclad printed circuit board material.
https://photos.app.goo.gl/Eu0UUbTdh9Snhnh53
 
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