Engine/Transmission (1998.5 - 2002) Engine missing intermittently when cold

[gonehuntingagain]

OK guys, I need some suggestions on what may be wrong. I'll try to include all the info I can think of.



When I start the truck either in the morning or after work in the evening, the engine sounds like it has some sort of an intermittent miss. You can hear the rpm's drop almost like you shut it of then turned it back on again really quick. It accelerates fine and runs good at anything but idle, but when you come to a stop and it goes to idle, the miss starts again.



At this time the check engine light has not come on, and there are no pcm codes set.

Fuel pressure is OK (measured at the VP-44 banjo bolt). Fuel economy has not gone down.

A new crank position sensor was installed in January.



The engine only does this when it is cold, when warmed up it is fine.



I'm starting to wonder if this is the VP-44 going south. I had a new lift pump put on it at 59K miles, which is shortly after I bought the truck, so I don't know how long it was running with low fuel pressure.



Any thoughts on what may be wrong will be greatly appreciated.



Thanks

Alan

 

[2-ND TIME]

missing a cummins?

Could it be an injector not spraying properly when it is cold? Maybe because the internal spring is broken?

 

[gonehuntingagain]

I would think that a broken injector spring would make it run like crap at any speed. Of course I don't know what a malfunctioning injector would be like either... .

 

[2-ND TIME]

Injectors ???

I had mine replace several weeks ago for they pop tested between 2500 and 3800 PSI well below the 4500 - +250 PSI it has run poorly for years. They dribbled or peeed in 1 to 3 nozzles very poor for them I though. With 223KKms Would love to have this thing :{ :{ :{ work with nononono problems for once. :-{}

 

[Elite1]

Originally posted by gonehuntingagain

OK guys, I need some suggestions on what may be wrong. I'll try to include all the info I can think of.



When I start the truck either in the morning or after work in the evening, the engine sounds like it has some sort of an intermittent miss. You can hear the rpm's drop almost like you shut it of then turned it back on again really quick. It accelerates fine and runs good at anything but idle, but when you come to a stop and it goes to idle, the miss starts again.



At this time the check engine light has not come on, and there are no pcm codes set.

Fuel pressure is OK (measured at the VP-44 banjo bolt). Fuel economy has not gone down.

A new crank position sensor was installed in January.



The engine only does this when it is cold, when warmed up it is fine.



I'm starting to wonder if this is the VP-44 going south. I had a new lift pump put on it at 59K miles, which is shortly after I bought the truck, so I don't know how long it was running with low fuel pressure.



Any thoughts on what may be wrong will be greatly appreciated.



Thanks

Alan

That sounds familiar... Last December I was visiting relatives in Colorado, my truck acted the same way you described... once it warmed up for a few minutes it ran fine, only did it first start in the morning. This is a Calif. truck and isn't used to the cold weather. It hasn't had any problems since, but then again it hasn't been in any sub 40 deg. weather since.

 

[gonehuntingagain]

I know it isn't the weather... it's getting warmer! It did not do this at all during the winter, even when below freezing.

 

[gonehuntingagain]

I went and filled up at Chevron 2 days ago, and added some cetane booster/injector cleaner to the tank. So far it looks like the problem has went away. I had fuel from Flying J in the truck for the last few tanks, maybe it wasn't up to par. Wouldn't surprise me since it was . 15 - . 20 cheaper than everywhere else.