I just completed a Glow Plug replacement on the 136k '02. No real snags or discoveries (aside from those %$#@&!! rear VC bolts). However....

Once I got everything buttoned back up (after VC off running and checks), I got the CheckEngineLight/rough idle when I started it up. Forscan check showed Cyls 4&8 as "High to Low Side Open". I wiggled the cabling around and that didnt do anything. Note I was very careful on the wiring, did the $0.25 mod (x2), bench checked the VC wiring harness for "ohmage" and power (both GP and Inj), so somewhat surprised when this presented. Note also that a Forscan check before I got started showed the usual Cyl 3&8 Contribution Test error (Cyl 3 actually went away after the work I did). So nothing happening with #4 or #8 beforehand. No probs on the 42-pin.

I also checked the armature spacing on all injectors (in place, I did not pull the injectors out). Surprisingly the 0.004" shim passed easily through 4 of them, 2 were tighter but could pass it through, and #4 and #8 were the tightest with the 0.004 (pass along one side but not the other), but very easy with the 0.002". No shimming was conducted, but I did drill out the plates for better draining).

Opened the VC up again and everything checked out. Unplugged #4 and plugged it back in again (purposely not doing #8), started it up, and Forscan'd. Only #4 showed the "High to Low Side Open" error, and #8's error went away (but still the CCT thing on 8). Also, the CheckEngineLight/rough idle went away. All codes cleared before I do a forscan run. The solenoids on driver's side are all snugged down per torque spec and check out, including #4.

With everything installed, GPs ohm out 2.6-2.9 from the 9 pin, and the injectors ohm out at 2.8-3.0 at the 42-pin. #4 specifically @ 2.9 ohms.

Did a PID run for awhile to see if anything jumps off the page. Attached are IDLE and 1200 RPM runs, as excel files. I am not seeing anything.

Quick rip of codes:

(OK) [10:04:25.982] KOEO Injector Electrical Self Test has been started
(WARN) [10:04:41.347] Test completed, found DTCs: P1274 (Cylinder 4 High to Low Side Open)
(OK) [10:05:04.259] Key On Engine Off On Demand Self-Test has been started
(WARN) [10:05:07.375] Test completed, found DTCs: P1274
(OK) [10:05:24.868] Key On Engine Off On Demand Self-Test has been started
(WARN) [10:05:27.986] Test completed, found DTCs: P1274
(OK) [10:05:56.029] KOER Switch Self Test has been started
(WARN) [10:06:13.545] Test completed, found DTCs: P1536 (parking brake), P0704 (clutch switch)
(OK) [10:06:29.440] KOER Cylinder Contribution Self Test has been started
(WARN) [10:07:32.719] Test completed, found DTCs: P0284 (good old Cyl#8)
(OK) [10:08:09.355] KOER Glow Plug Monitoring Self Test has been started
(OK) [10:08:16.108] Test completed successfully, no errors found
(OK) [10:08:30.477] Key On Engine Running On Demand Self-Test has been started
(WARN) [10:09:50.063] Test completed, found DTCs: P0542 (AIH unplugged)

I have a new UVCH harness (from RiffRaff!) I will fetch and try that out. Since the harnesses checked out on the bench, I didnt bother grabbing them out of storage.

I believe I have checked all the usual characters. That #8 High to Low Side Open code went away (after I opened the cover) is puzzling, and could be telling me something? Were these just ghost codes?

Anyone have some thoughts on this?

Thanks!

 

I think you are headed in the right direction getting the UVCH ready for install. Are you working with original valve cover gaskets and harness? It may just be aging and disturbing them to change the glow plugs made it upset

 

^^^^^
Agreed with the above thoughts.

If you went into the heads/ removed the Valve covers that is...List of things to do.
Valve cover gaskets if more that a few years old.
Under valve harness's, again if more than a few years old.
Rockers re torqued to spec.... every time. Even if done last year it is always a good check.
Injector hold downs.... every time. Even if done last year it is always a good check.

Also I would suggest stripping several inches of the engine side harness and visually as well as with fingers check for any damage. Be sure to use good foil and get the shields good when you re-wrap the harnesses.

And yes, trust Riffraff for OEM only parts..

 

After further troubleshooting, an update...

Continuity check on new/spare UCV harness - everything OK

Swapped out wiring harness - still have the #4 P1274

Pulled off solenoid and re-installed. Same code. I did not think this was going to change anything.

Checked continuity across the solenoid contacts - everything ok.

Nothing different on codes after swapping out the harness.

Pulled IDM plug - have continuity across the IDM to 42-pin plug (all cylinders, but this was no surprise).

Now I couldnt get ohm readings from IDM plug to Cyl4 - or any injectors for that matter. As a meter check, I did get readings from 42-pin to each injector. Not sure what that is about. Since everything checks out continuity wise, I am not getting too worked up over that.

When this first presented, the engine idled rough - which is to be expected. From what I understand, if the high to low fault presents, the PCM instructs a minimal flow through the injector and throws the CheckEngineLight (ostensibly to keep it cool while the engine is running).

After I pulled the cover off to re-check - and unplugged and plugged #4 only back in - the code persisted, but the CheckEngineLight went out and the engine idled normally.

One oddity, which I think is telling me something: I inadvertently ran a buzz while the 42-pin was disconnected. The only error? Cyl4 high to low side open.

I want to exhaust all options before I put the cover back on and take it for a spin. Any ideas?

 

"Valve cover gaskets if more that a few years old". Checked them out and they were solid (I do have new spares)

"Under valve harness's, again if more than a few years old." Checked and rechecked these and they passed with flying colors - ohms and power.

"Rockers re torqued to spec.... every time. Even if done last year it is always a good check." Checked these also. No need to tighten anything up.

"Injector hold downs.... every time. Even if done last year it is always a good check." Ditto.

"Also I would suggest stripping several inches of the engine side harness and visually as well as with fingers check for any damage. Be sure to use good foil and get the shields good when you re-wrap the harnesses." I really gave the wiring an extensive check. Everything looks good, nothing even resembling sketchy.

 

I cannot say for sure if they are the original gaskets and harnesses. I was expecting to see a Ford part number on the harness, but nothing. Also, the connector on the gasket simply said it was reuseable and "1826703C1 Rev C". That number shows up as an International part.

Injector 8 is an AE, but not sure if that was from the factory or not. The rest are ADs and the serial numbers suggest they all went in at the same time.

Its 50-50 that covers have not been pulled on this thing. If the AE was put in at the factory, I would say they have never been opened up.

I made something upset. Even swapping out the harness yields the same error.

I am puzzled.

 

Not sure what is going on....

Swap #4 Solenoid with #2. Same code: P1274 (High to Low Side) for #4.

Swap in rebuilt IDM. Different code, P1272 (High to Low Side), now for cylinder 2. This kinda makes sense? The "faulty" #4 solenoid is now on 2.

Also I now have a Bank 1 High to low error and Cylinder 8 High to Low (which presented at first with original IDM along with 4, but went away when I unplugged 4 only). I do not believe it as the engine starts and runs uber smoothly. I would expect the rough idle and check engine light on for that. Nothing doing. Also, ohm check IDM plug to injectors check out @2.9-3.0 on passenger side and 2.8-2.9 drivers side. None of these codes reported are based on actual open or high resistance wiring/connectors.

Restore Solenoids to original location. P1272 (for cylinder 2). WTF? Technically should show as 4 - if the solenoid is what is triggering the code in the first place.

I am starting to convince myself the IDM doesn't wipe out its codes entirely. And the batteries are disconnected at least 15 min while switching things around.

I run the tests multiple times, clearing FORSCAN codes each time.

Lastly, I restored the original IDM (along with the solenoids in the correct place). P1274 for #4. But is it real? This IDM was throwing the P1274 before I changed it. It never picked up the solenoid swap before.

At a minimum I have a solenoid problem, but technically only noticeable when I switch IDMs.

So a couple of questions:

1. Bad or compromised solenoid - is that a thing? I havent seen too much on that.
2. "Ghost" codes - is this a thing?

TLDR: after glow plug replacement, something triggered a #4 and #8 High to Low side fault, the "Malfunction Indicator" light and rough idle. Opening valve cover and unplug/plug #4 cleared #8 but not 4. MIL and rough idle went away. Install new Ford/RiffRaff UCVH - same error. Switching solenoids didnt show up on the original IDM, but was picked up by rebuilt IDM. Swapping solenoids back was not picked up by rebuilt IDM, but may have been by original IDM. Lastly, every &^%$#& wiring type test and inspection yields all is normal. FORSCAN cleared multiple times/batteries disconnected every time changing something.

Lastly, after reading a few threads on here about someone dropping a nut or bolt into the engine, I decided to hedge my bet and made a cardboard prophylactic. Would have been even more needed if I was doing some shimming. See picture.