7.3L Rough Idle after sitting overnight

[dmpruitt01]

I have a 2000 7.3L PSD, 199,000miles. The truck is hard to start and has rough idle after sitting overnight or more than 6hrs. I can hammer the throttle a time or two and it clears up and idles fine. Also, the truck has a slight miss at light throttle, but goes away when adding throttle. This clears up after driving about 15 mins. I have replaced CPS, ICP, and fuel filter. WHAT'S MY PROBLEM???

[dmpruitt01]

No Codes, No check engine light. Forgot to mention that.

[dmpruitt01]

I have also changed intake air heater relay, glow plug relay, all 8 glow plugs, all glow plugs ohm out good, I'm getting tired and broke with throwing parts at this truck, and I'm getting frustrated! Can't find anything on the forum with this exact problem. Someone told me that it sounds like air getting into the fuel system?? Perhaps injector O-rings?? Someone please help me!!!

[ELSUPERBEASTO44]

DID YOU EVER FIGURE OUT WHAT WAS CAUSING THIS? MINE SOUNDS LIKE IT IS DOING EXACTLY THE SAME THING YOURS IS AND NO ONE SEEMS TO WANT TO HELP ON THIS SITE...

[dusted4eva]

Sounds like water in the fuel or the under valve cover harness.

[dmpruitt01]

Mine turned out to be a "sticky" injector where the previous owner did not change the oil properly. A local diesel mechanic told me to drain about 2.5 quarts of oil out of the truck, and replace it with diesel fuel. Then drive it for 200 miles or so. I have driven only 84 miles now after doing this and the truck has done perfectly ever since about 40 miles. I'm going to drive it another 100 miles or so. The faint "miss" during light throttle is still there, but goes away within about 2-3 mins now, but I think that is a different problem caused by a small fuel leak I found yesterday in the fuel line coming out of the fuel pump.

[greasyF250]

2.5 quarts of diesel in your motor oil ??????? WTF????????????????????????????????????????????? This doesn't sound good. I need to keep an eye on this........................

[dmpruitt01]

I was skeptical at first too, but I was willing to try anything to help get my truck running properly. So far, the truck is running just fine and starts good. The only problem I'm having now is that the fuel "leaks back" after sitting for a long period of time and the fuel pump runs for about 30 seconds before it pumps up. Maybe getting air in the fuel causing the "light miss" still working on that.

[MIG]

I have a 2001 doing the same thing.I have replaced everything under the hood and that annoying miss is still there.It will go away after warm up then comes right back as soon as it cools down.I think it is the under valve cover harness not making a solid connection on the injectors and glow plugs.When i rev up the engine above 1500 rpms all codes go away.The codes i get are 1,3,5,8 glow plugs and injector driver circuit.Now before i had changed the uvc harness i had none of these failures.


So i think the problem lies in the UVC harness i replaced, come to find out it was made in china sold as the Dayco brand.Is this harness crap? I think so im going to order an OEM ford and let you know.I read in one thread that someone had this issue with an aftermarket harness before.

[dmpruitt01]

Originally Posted by MIG

I have a 2001 doing the same thing.I have replaced everything under the hood and that annoying miss is still there.It will go away after warm up then comes right back as soon as it cools down.I think it is the under valve cover harness not making a solid connection on the injectors and glow plugs.When i rev up the engine above 1500 rpms all codes go away.The codes i get are 1,3,5,8 glow plugs and injector driver circuit.Now before i had changed the uvc harness i had none of these failures.


So i think the problem lies in the UVC harness i replaced, come to find out it was made in china sold as the Dayco brand.Is this harness crap? I think so im going to order an OEM ford and let you know.I read in one thread that someone had this issue with an aftermarket harness before.

Let me know what you find out with the UVCH. I haven't replaced mine, but still could be a factor in the miss. Mine doesn't throw any codes or check engine lights, but the miss sounds just like yours.