Guys,

I have noticed as of lately when the air temp seems to be below 20 or so that I get a shudder or stumble. It does not seem to be there when at 30 or warmer
I have just changed the fuel filter thinking that it might be a small gelling issue as a couple of weeks ago we had some single and below digit temps...

Any ideas?

Pete

Your not nearly cold enough to worry about fuel gelling on you. Describe this 'shudder or stumble' is it all the time, under load, during cold start???

tdg,

It happens with the motor warm, I let the truck run 10 min or so before leaving from work.. leave at 1am most nights... under load after 5 min or so.. and continues for a bit...

IT does it randomly, but every couple of min or so... almost like a studdard .. if It was a gas motor I would say missing ... but just not sure on this case.. and also only happens when cold out side... not motor cold

Pete

What year model truck is this? Have you ever replaced the pump/injectors/glowplugs/supply pump etc? Do you get any white smoke when it happens? It only happens under load after the engine is warm? Does it always eventually clear up when coolant temps get high enough?

TDG,

98 6.5, pump was replaced spring or so last year. 1/2 of the glowplugs were done, have not had time to get to pass side as of yet, lift pump was done at same time with injection pump
as far as some, just about the only time I notice it is around midnight or 1 am when I am leaving work, so I can say there is any smoke.

I do not notice the issue when the outside temp is above 30 or so
Pete

TDG,

Drove home tonight, same route as normal, temp outside was 30 or so.. no noticable studdard on engine. same speed, nothing different.

Any ideas?

Does it fire right up for you on all 8 when its below 30? That would pretty much rule out glowplugs. Next would be injectors... I've seen trucks with TDC offset set with the pump too far retarded, causing a slight hesitation during rev and acceleration. All you need is a scanner to see where yours is right now, your '98 will have no trouble relearning, it will learn itself as soon as you get to engine temp.