need knowledge

Do you have the codes?

 

Yep need the exact code to narrow down the control valve or which intake valve actuator is malfunctioning. There is a series of them under your valve cover. One of the actuators can have a bad o-ring or the actuator itself is bad. The codes will reveal which one.

Here's a helpful offsite thread.

http://www.thedieselgarage.com/forums/showthread.php?t=113963

 

You have to go through the proper troubleshooting procedures for your specific codes. Acerts were known for injector harness failures that cause low voltage and low current codes to injector and actuators. Replacing the harness' will be about 8 hours if you've never done them before. They are also known for actuation pressure sensor failures. The valve actuator housings also crack and need to be looked at closely. Cat came out with an updated housing that thicker on the outer 2 stud holes.

The harness issue has caused a lot of misdiagnosed actuators and injectors. How many miles are on them? Are they original? If you have no way to test them (an ohm meter does not work), I'd just replace them now, it's only a matter of time before they fail. I test injector harness' by totally disconnecting everything. I put 12 volts to each wire and measure voltage with LoadPro test leads to put a load on the each wire and look for a voltage drop. They almost always ohm out good when they are bad.