Engine/Transmission (1994 - 1998) 2000 rpm no load stumble

[tmassey]

Hey there, i dont post here very often but you guys have helped me out a great deal so far and im hoping you can once again.



when the truck is cold it has a stumble (miss) right at 2000 rpm (in neutral and creeping up in rpm), and after it warms up it for the most part goes away if i creep up in the rpm but if i just throw a rev it has the same bad miss, any ideas? I just finished replacing all the fuel lines, removing fuel heater, and readjusted the gov arm. two or three months age i had the timing bumped to 15. 5* any help in what direction would be great, thanks in advance.

 

[JoeBioDiesel]

Hi TM,

Any time I've seen a 12V miss at higher revs when cold it was either

1) the timing slippped-most common

2) An injector or two had a crummy spray pattern-less common



I would advise you to stop revving it when it was cold, unles there's a reason you have to do it. I don't think I'd try to fix an injector problem unless it was huffing a little black smoke when it wasn't supposed to be.



Joe

 

[tmassey]

just jow common is it for the timing to slip?, the injectors have about 180,000mi on them now, should i look into a new set. this thing does smoke like a train but i figured it was because of the stock turbo and the 14cm housing (lag). when i say its missing when cold i mean around 140-160*, just under operating temp

 

[Vaughn MacKenzie]

tmassey it's pretty normal for a 12-valve to do that within a minute or two of starting, especially in cold weather, but shouldn't do that for much longer than that or if the weather is fairly warm.
It sounds like you covered your bases on the fuel system, but are you confident there are no air leaks? Did you service the prefilter?
Fuel Pre-Filter Cleaning on Ram/Cummins

When you say it smokes a lot, is it white, blue or black? Does it smoke if you roll into the throttle easier and let the turbo keep up?

Vaughn

But I agree with Joe, don't free-rev it that high