So.

I have had many 7.3's. And know all the randomness little problems they have from the factory.

This ex has me a little stumped though. I bought it about a year ago with some random issues. It would randomly die while driving. While driving it would start to shudder violently and then lose power and die. Had codes for IDM not talking to CPU. Replaced IDM and CPS along with fuel filter, also dropped fuel tank and did in tank mods. And it ran great since.

So my new issues is that while driving to visit family this thanksgiving on the way up. It's a 200 mile trip and I was about 1/3 of the way there at 530am while one cruise control it did that shudder for maybe only 1 or 2 seconds then ran fine again. No speed loss at all and still on cruise. It was violent enough to wake my wife up and she say oh no is it doing it again? So I took it off cruise and drove the old fashion way. It seemed fine and then about 30 min later it did the exact same thing again for just 1 or 2 seconds, this happened 3 more times the rest of the trip. About every half hour. Made it to where we were going fine.

So for the return trip I was thinking of how to solve the problem, and before we left I though about when this happened more severely when I first got it. Both times I was using cruise control. So for the return trip I didn't use the cruise control at all. It ran like a champ with not a single hick up.

My question is I know the cruise uses the computer to keep the EX at a constant speed. Is there maybe something in the CPU that when using the cruise mode is screwed up? Causing this random issue?

Thanks

It's a 2000. 4x4. 7.3 psd limited with 208000 miles

 

Did you notice when it shuttered? Was it when going downhill? This might be better over in the 7.3 forum rather than here.

Here is something that might be related to your issues:

99' 7.3 powerstroke pulsing at very light throttle in cruise only, starting hard morn - Diesel Forum - TheDieselStop.com

 

Moved to the 7.3L PSD forum.

Stewart

 

It usually happens going up a light grade in cruise.

I think I'm going to look into rebuilding the FPR because it has 208k on the little spring and possibly could be stuck open. But want to check fuel pressure first. What would be the simplest way to do this? I know there are two ports on the back of the fuel bowl so does anyone have a cheap simple set up for this?

 

I've seen bucking at light throttle with loose injectors. I read that thread where the Throttle Position Sensor is suspect, and where the problem was solved by cleaning the IDM pins and re-applying dielectric grease to the connector. I also suspect a partially-clogged injector nozzle can cause bucking at light throttle, but I have nothing solid to back that up.

 

What confuses me is that it seems very random. I'd think that with a clogged injector and loose injector it would happen more often. Normal day to day driving including some short highway it completely fine. Seem like after a long distance of driving at high way is when it becomes and issue. Almost like being fuel starved from trying to accelerate up a hill. And if you override the cruise and hit the go pedal it just gets worse. If you let the truck slow down and limp up the hill it will make it as long as it's not super step or long.

Also I have replaced the IDM 1500k ago and cleaned and re dielectric greased connector.

 

Ah... you may be describing aerated oil. I have that, and it's a nuisance - but one I may have to live with for a while. A possible cure is to pull the engine and redo the seals and replace the pickup tube in your oil pan. I know my truck misbehaves a little and sounds a bit odd after long hauls. One glance at the dipstick shows a lot of bubbles, but it's no real harm as far as I'm aware. Fresh oil is less likely to do this, and thicker oil even less - but I use 5-40 oil in the winter, so I'm stuck with it.

 

Sounds a lot more like low fuel pressure than aerated oil to me.

 

I won't disagree. I know I have good FP (or so the gauge says) when I experience it with Stinky.

 

I had a similar problem with my van, the truck would drive for for many miles on cruise, them for no apparent reason the cruse would cause the engine to stumble then recover. It took a while to figure out during daylight hours, but I was getting a "Brake" light on the dash when the cruise would act up. I did some checking and found that the momentary contact switch on the parking brake arm was not making a solid contact when in the released or non parking position. I did a slight adjustment of the switch contact mechanism and have no problems since. Might want to check yours out.
Nick