First of all, great forum here. I've found a wealth of information and performed three free fixes on my truck so far (overhead console trip computer, A/C clutch gap, slip joint grease).

A brief history. Just bought this truck a couple weeks ago. Seems to have been well cared for by the previous owners (Carfax showed two, with no collision incidents). This is my first diesel. Purposefully bought a 7.3 based on previous internet research. Cost was a factor, as well.

Truck specs - 02 F350 DRW 7.3 4x2 Auto, 146k miles, all stock (no chips, intakes, exhaust or other mods). Just put two brand new batteries in it last weekend. Other than that, been trouble free.

Now, maybe I'm being a bit paranoid. This is a new vehicle to me and my first diesel. But I've noticed the engine seems to have just the slightest miss, like one cylinder isn't quite firing as well as the others. It is most prevalent between 1500 and 1700 RPM in any gear. The miss at those RPMs is more pronounced, especially at light throttle. Roll into the throttle and it pulls like a freight train. It also idles relatively smooth.

I'm running right now on a bottle of Diesel Kleen I added to the last partial fill-up (brought it up to just over 1/2 tank and dumped it in, based on their recommendation that a first application could be doubled). Also opened the fuel bowl drain for about 15 seconds earlier just to make sure there wasn't any water in it (seemed to be draining fuel from the get go).

Stopped by O'Reilleys today and had them check for any codes and there were none (not sure if a standard scanner at the auto parts store would show any diesel-specific codes or not, but figured for free, might as well give it a shot).

Any ideas? I plan on putting on an HPOP crossover sometime in the next few weeks. Curious to see what that might do. Until then, I'm open to any suggestions, even if they're something along the lines of "yeah, you're fine, they all do that a bit".

Thanks! And thanks for the wealth of information I've run across here.

 

A slight miss is hard to diagnose across the internet but it sounds like you're on the right track. Is the problem while just cruising in that RPM range, or does it happen if you floor it and speed up through that same range?

Have you changed the oil since you got the truck? What about the fuel filter?

 

Seems to be more at light throttle. I'll see next time I run it up, though usually at heavy throttle, it's running higher RPMs. We do have a pretty steep hill coming up our street. I'll try to pay more attention when climbing that, as it requires a bit more throttle at lower RPMs.

Oil was changed by a reputable local place at 145k when the dealer put it out on the lot, so it just has 1,000 miles on the change. Level checked fine a couple hundred miles after I purchased it. Fuel filter is what was in it. Planning on replacing it at 150k along with next oil change (along with a cooling system, rear axle and tranny flush and fill, as well, just to know that it has been done). Air filter minder is at only about 10%, so it looks like it was well maintained prior to me buying it, or at least well serviced prior to it being put on the lot.

 

IPR would be my guess. My truck did this when you feather the throttle. Injector pressure regulator. Injectors need a constant pressure I believe, and mine was varying by A LOT! . Others might have a better idea, but from what you said and my experience it may be that.

 

Thanks, Mitch. I'll add that onto my list of things to try.