Engine misfiring until operating temperature reached

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Jan 25, 2012 | 01:27 PM

pditmars

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Trailering

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Engine misfiring until operating temperature reached

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9; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} </style> <![endif]--> My 1997 F350 7.3L Powerstroke (290K miles) has just developed a very predictable hiccup.

In the morning, after a 15-20 degree night, the timing of the wait-to-start light is normal. The temperature gauge is below the cold mark. The truck starts and runs perfectly. The glow plug relay shuts off normally.

I drive it on the level for about 1/4 mile and it all of a sudden it loses power and acts like several of the cylinders are not firing (very, very rough). The check engine light comes on. If I shift into neutral and let off the accelerator it continues very rough on idle, threatening to die, but never quite dying. If I press the accelerator it will very slowly build up RPM. Exhaust looks normal (no clouds of white smoke).

If I hold the speed at about 1500 RPM for about 5 minutes, the temperature gauge will crawl up off the cold mark and just as it does, the engine reverts to running perfectly and the check engine light goes off immediately. Problem does not happen again during driving.

This behavior is 100% repeatable (4 times), and in addition, if the engine is not dead cold (but still below the cold mark), the problem happens anyway, but it takes much less time to fix itself. So...

It seems like a temperature dependent problem affecting the fuel supply, though why it should run perfectly at first, I can't understand.

Some more details:
- It's a completely stock engine.
- It's been cold here at night for a couple months. This is first time this problem has occurred.
- Camshaft position sensor replaced 40K miles ago (Ford Warranty Service)
- Glow plugs and relay replaced 50K miles ago.
- Injectors flushed 15K miles ago.
- Oil/Filter change performed 50 miles ago with SuperTech 15W-40/Fram Filter (same stuff I always use).
- Air filter is clean and filter monitor confirms this
- No obvious contamination in fuel. I drained a bunch...
- Fuel filter has 20K miles on it (I guess I need to change this soon!)
- Don't have a diagnostic tool to check engine codes and I'm a LONG way from any shop.

Does this sound like a problem you have seen? I'd sure appreciate any pointers that you can give me as to where I should look to fix this one.

Pete

Jan 25, 2012 | 01:50 PM

mojoman

Senior User

Joined: Aug 2006

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worn injectors is my guess...at 260K I had similar probs...Rosewood Diesel fixed me right up...but thats just my guess...hth

Jan 25, 2012 | 03:33 PM

bad12jr

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Joined: Dec 2008

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From: Maysville, Kentucky

Plug it up and see what happens. This should get it above the cold mark. Could need injector o rings.

Jan 25, 2012 | 05:27 PM

Action4478

Hotshot

Joined: Aug 2006

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Get the code ... It would help to know what EOT sensor is reporting also

Intermittent CEL could be UVCH

Is the C case full?

Jan 26, 2012 | 05:19 AM

DZL JIM

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Joined: Sep 2003

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From: North East Ohio

Bad/worn injectors would run baldy as soon as it was started. Not work, then not work, then work again.
Got to be another issue going on.
Kind of sounds like loss of HPOil or loss of fuel pressure somehow, once warms up fluid flows and starts to run better. ??

Could also be IDM. I have heard some weird reports with them and temps, not really sure why.

__________________
'96 7.3 F-350 Reg Cab 4x4 - bought new.
'04 6.0 E-350 custom 4x4
'08 6.4 F-550 Reg Cab 6 spd 4x4
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Jan 26, 2012 | 08:23 AM

pditmars

Thread Starter

Trailering

Joined: Jan 2005

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Update (and question on Scan Tools)

Thanks for the replies. I had the same impression as DZL Jim. Gotta be something like HPOil pressure wrong or fuel delivery screwed up after initial diesel in galleries is used up.

The crankcase is full and the HPOil reservoir is too. I left the truck out in the snow last night and swapped fuel tanks to see if the problem gets worse. Assuming it craps out again this morning, I'll try plugging it in tonite. It looks like I can check the EOT with (mostly) an ohmmeter, so I'll do that too. It's a bummer I can only really work on this once a day, but at least I'm still mobile...

I'm willing to spend a few $$$ to get a scan tool, but the Rotunda NGS ($3000?) is out of my league. Can anyone point me at a reasonably-priced option for a scan tool?

Jan 26, 2012 | 08:35 AM

fordpride

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From: Livoina,La

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Mar 17, 2012 | 12:19 PM

pditmars

Thread Starter

Trailering

Joined: Jan 2005

Posts: 20

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Update - Problem resolved

Bought Auto Enginuity from RiffRaff Diesel. Nice program, and I can thoroughly recommend it.Buzz tests on the injectors sounded good, and the cylinder contribution test passed. However I kept seeing a P204 code (among others). Popped a valve cover off of the engine, and lookee here! a burnt out internal connector on the wiring harness. Replaced it and all is good with the world. Talking to people subsequently, I heard that this is a common occurrence on 7.3 Powerstrokes. One mechanic that I greatly respect says that he changes the harness whenever he has to do glow plugs. Sounds like a bit of overkill, but maybe every two glow plug changes (120K on my service schedule) would be an appropriate interval.

Lessons learned.
1) Get a scanner!
2) Don't assume a problem is temperature related, even if it only happens when it's cold out.
3) Consider changing the wiring harness if you're running over 200K on originals.