So I am driving the ol Cummins hard today rowing through the gears and I shift into 4th and get on the throttle hard shortley after shifting the engine sounds loud/bad like it is lugging. I let off he throttle and sound goes away but if I accelerate hard(only when hard) at about 1600rpm or less the sound is there again. Hard sound to describe but it sounds like the truck is lugging/bogging. If it were a gas job i'd say it had to much timing and was pre-detonating. Only really notice it in 4th and under 3/4 to full throttle. Boost is aprox 26-35 psi and egt is about 1050 and climbing through 4th. Any ideas.

 

From your sign i would say that your boost is to hi and is surgeing at low rpm........or if it is, a ping or vary miled knock it could be the timinng

Could have the wire fallen off or came lose on the KSB(Allows the timing to advance when cold!)?

Have you bump the time up at all?

 

I have not done any advance on the timing. If the KSB wire is one of the 2 wires i can see on the injection pump then no as they are both still on. I do still have the baby h1c which probably should not be running at 30+psi. Would this turbo surge because I am spinning faster then it was designed for? I thought surge was the turbo producing more boost then then the engine could use, there fore forcing the air back into the turbo. Are you saying I am making to much boost at too low an RPM?

 

the wire on the lower side of the pump next to the timing cover

Yes