Engine gurus please

[PowerStroker444]

On Sunday under hard acceleration the truck seemed to miss/hesitate. Yesterday on the way home from work it started idling rough and running rough to about 1300 rpm. It cruises fine. Cps was changed 5k ago. Oil has 3500 miles on it and the fuel filter has 8k on it. All ideas appreciated. No chip or programmer.

Thank you

 

[Dieselmaster]

I wish I could offer more help than just a :shrug:

If you have a spare CPS then that would be the first thing I would try... I have heard of guys that go through them quick...

Did you get any codes??

I would try pulling them to see if anything shows up..

 

[Swany]

I'd change the oil and the fuel filter. You may have some gunk in the fuel filter housing, I usually change mine at 10k but you could have gotten some crappy diesel.

 

[Whit]

Not to familiar with the strokes but I think it is starving for fuel, change the filter and see what happens.

Cheers, Kevin

 

[morepower02]

Aso check the electrical connections on the valve cover gaskets. There is a connector on each one facing the engine valley. The connector is blue and controls the injectors and glow plugs. I found out that my motor would run off of the right side four cylinders when my connector came loose. It was kinda strange seeing the truck half ass running and the pyro that is drilled into the left manifold say 100 degrees while running. Wiggled the connector on the left bank and away we went

 

[PowerStroker444]

Thanks for all the replies. Now it runs fine under acceleration but still rough at idle and shakes until about 1300 rpm. I got no SES light either. I too was thinking about the valve cover connectors. I will change the fuel filter this weekend and check the connectors, too busy this week at work.

Thanks again.

 

[PowerStroker444]

I changed the fuel filter, looked almost new after 8k. Valve cover connections look good too. Still no change. I'm thinking something electrical, I hear no unusual mechanical noises and it runs good after 1300 rpm

 

[PowerStroker444]

Changed the oil and filter with no difference.

 

[morepower02]

Sorry, but I don't know what to check next.

 

[Dieselmaster]

I think its time to check the injectors....

 

[hheynow]

If there is an Autozone near you, I believe they offer free use of scanners. HERE is the complete 1999 diagnostic codes. I'm not familiar with the super duties, but in the 94-97 year models there is a fuel regulator screen which can become clogged which could be your problem. Cleaning it is a possible fix, BUT I'M NOT FAMILIAR WHERE YOURS MAY BE IN THE SUPER DUTIES. My $.02

 

[PowerStroker444]

I don't think it is fuel related because it runs pretty good in the upper rpm range.

 

[PowerStroker444]

If I remove the IPR valve how will I know if it is bad?

 

[RenoF250]

I don't know but it seemed to me that the running rough at idle but good over 1,300 can be caused by a bad throttle pedal. I would agree that it is probably not fuel starvation if it runs fine at higher rpms. I would somewhat suspect the CPS since it is a hall effect sensor and they sometimes have a problem sensing slower speeds when they go bad. They are electrical so miles don't really matter, they go bad when they feal like it.

 

[geonc]

Originally posted by PowerStroker444
On Sunday under hard acceleration the truck seemed to miss/hesitate. Yesterday on the way home from work it started idling rough and running rough to about 1300 rpm. It cruises fine. Cps was changed 5k ago. Oil has 3500 miles on it and the fuel filter has 8k on it. All ideas appreciated. No chip or programmer.

Thank you

What year PSD are you talking about?
A 10 k mod will sometimes give a rough idle.