Hi Diesel Doctors! I'm new to the site.... first time posting although I've been reading from the side lines for a couple of months. Very informative site!
I have a friend who has a oo 2500 with Van Aiken chip, 60kkilometers(36kmiles) new lift pump this week and under load the engine seems to pulse as in rocking back and forth . It is very slight but certainly noticable . Any ideas or suggestions?

 

Maybe tranny shudder or injection pump dying. Does it occur with the box off?

 

Yes engine acts the same whether the box is plugged in or not.He's hoping its not the vp44!!!I guess its a trip to the dealer and see whats causing the prob. Thanks

 

Have you tried the APPS reset? I'd try that before I'd do anything else. Look in the tech facts and it should give you the procedure for doing that.