He has an unmolested 2004 6.0, When he is in a hard pull his truck starts surging. It also blows blue smoke when it surges. Some time ago he had some injectors replaced at that time it was doing the same thing. My question is are the injectors bad or is something else causing his peoblem. Thanks

 

Need more info...

Mileage? Any codes? What's the boost? Since it's an 04 I'm assuming there is no boost gauge, unless he added one...?

 

Here are a couple of other ideas.

Has your buddy done oil changes on a regular recommended basis?
Did they update his truck to the latest flash?

Trucks built before 1-17-05 that exhibit buck/jerk, hesitation, lack of power, stalling, stumble, black smoke, surging, rolling idle, changes in engine sound at idle or when driving at a steady speed, or with the trouble codes P2263 or P0299, may have an exhaust backpressure sensor signal that is incorrect or erratic. A revised EBP sensor is available if this is found to be the case.
Since many trucks ahave already had the EBP sensor replaced with the current level part, the sensor part number should be inspected. If the part number on the sensor is 1850353 over a number starting with "C1", the sensor does not need to be replaced.

On 2004-2006 engines that exhibit a light surge on light acceleration up to 50 MPH, typically after a cold start, at steady speeds between 1800-2800, or when climbing a grade (towing or not), may have a sticking Variable Geometry Turbo actuator. You would need to replace the VGT actuator and the turbo lube oil line.

 

dont know what he has done but i know that he is going to do,(CUMMINS) thanks for your time