'01 7.3L Rough Idle w/Service Engine Soon light
 

FTE,

I've seen a lot of great help from others on this site, so I thought I'd ask for some myself (first post).

I have an '01 F-350 dually with the 7.3L diesel. Yesterday it gave me the "Service Engine Soon" light and started to run *rough* -- as in low power, lots of shaking, and sounded way off. I'm no expert or mechanic, but it sounded like a misfire. This condition never happened immediately after starting, but only a few seconds/minutes after running (usually when the engine was operating at idle) the conditions came back and wouldn't go away. Well, once or twice it went away briefly and then came back.l

Well, I limped into town and took it to a mechanic and immediately he noticed my fuel filter was way old. I changed it out for a brand new one and then ran 200 miles on the truck and it felt brand new. No issues. So I know that this action at least did something. I also changed the air filter and ran some SeaFoam into the engine. So I know one of these actions (most likely the over-corroded fuel filter) did something good.

Since then, I've had the same problem happen to me twice, but only for very brief periods (not enough time to stick my code-reader into the console!). Once was when I was idling for a long time down a mountain pass in Drive. Light came on for 2 seconds and then went out. I did not notice a change in engine performance. The second was just today from switching from 2nd to Drive and, in idle, gave me the same indications (light and rough idle) for about 5 seconds, and then everything went back to normal.

I'm not sure if what I did was a quick fix for a more serious problem (because it certainly did fix the problem short-term), and I *do not* want this truck to be damaged because of mal-treatment or bad service. I very much appreciate the advice and help that FTE can offer -- it certainly means a lot!

Alex

Welcome to FTE!

Might as well try to pull the codes, if for no other reason than to discover if your code reader works with the truck. Many code readers will not work on 7.3s.

First thing I'd look at is the underside of the wiring harness located over the driver side valve cover. It connects to the 42 pin connector. It can chafe on the valve cover and the bare wires can cause intermittent shorts. Some tape on the wound and a chunk of split heater hose for protection might be all it takes.

The symptoms don't sound like a fuel issue to me. Process of investigating and changing the fuel filter may have moved the 42 pin harness out of harm's way for a while. That said, pulling the fuel filter for a look see is a good idea. If it's gunked up again we have another avenue to explore.

I'm a Seafoam fan in older gas vehicles, but not in a 7.3 diesel. For these I use a good fuel additive like Power Service at every fill up to add lubricity and prevent fuel gelling in winter. No oil additives, since they sometimes do not play nice with HUEI injectors. 6.0 can benefit from oil additives, but the 7.3, no.

get the check engine code and report back for diagnosis, the code should still be stored on the computer

Could also be time to only invest 50 cents "in" it...50 cent mod

Don't know if it would create a Check Engine Light, but you might check the ICP switch on top of engine to right of fuel filter. Pull the connector and check for oil..... if there is any oil in connector get a new OEM ICP. Most of us have agreed that only OEM if its an electrical part.

It wasn't intermittent but the last time that happened to me one of my injectors was unplugged.

Since yours is intermittent it could be the UVCH. If yours are older they might not be the newer style plug. The older style was a hit or miss on whether the connection would stay tight or the plug might walk out causing poor connection. This is fixed by the 50 cent mod as timmyboy76 said.

Welcome aboard.aboard.
You've got good advice from everyone so far.
Please report back when you get it fixed. That helps the next guy out.

The injectors are held open by oil pressure....
If your oil is 'low' and not being picked up, the/some injectors could be slightly closed. (check your oil level)

Also, just by changing your oil and filter will most of the time make the truck run very 'different'.... (better)