VGT question.

[suprdtydvr]

Does anybody know if the PCM issues a command to cycle the VGT on engine start-up?

Thanks,
JR

 

[blacksnapon]

I think its dependant upon programming level and any "problems" detected. The pcm will cycle the vgt if there was a problem detected in an attempt to find "common ground" or "relearn" the correct strategy.

 

[suprdtydvr]

It is just funny, every now and then I hear something under the hood on start-up. It is mostly after the truck has sat for a few days and it sounds almost like a pop and groan (like the actuator just freed the VGT?). No drivability problems and the truck has never sat for more than a week.

 

[blacksnapon]

It is just funny, every now and then I hear something under the hood on start-up. It is mostly after the truck has sat for a few days and it sounds almost like a pop and groan (like the actuator just freed the VGT?). No drivability problems and the truck has never sat for more than a week.

The "problem".......temporarily stuck vanes. Solution, cycle the vgt to "find" the proper spot to be in.

 

[d-kuzmen]

The newer program will cycle the vanes every so often, not usually on startup, I have heard some trucks with "noisey" vanes in the turbo you could accually hear them moving, what your hearing is probably the vanes un-sticking themselfs, when the truck startst he vgt comes on to set the vanes in there proper position for idle.

 

[m-chan68]

If I'm not mistaken, the most current calibration will cycle VGT full open and full close if it detects extended engine idling.