why would it be worst below operating temperature ?

 

everything is srunk down becuase of the motor being cold

 

It is a completely normal thing...

When cold the EBPV... (EXHAUST BACK PRESSURE VALVE) closes and helps to build back pressure and heat. This warms the motor quicker.

The PCM uses oil temps, pressure and air temp to control this valve, as well as the back pressure sensor.

If anyone of these is on the fritz it can cause the EBPV to open and close when there is no reason or after it should not be.

But for the most part it sounds as if there trucks are running normal. Let them warm up to temp before driving and the "symptom" should go away.

 

this is new to me. i would like to hear more.

 

What part?

It could be a bad/dirty IPR, but I doubt it as its effecting both trucks...

As well, check every diesel website out there every year about this time... this same type of question/concern comes up...



Its part of the cold weather package, Ford should have done a better job edgicating people...LOL