Hi All!
Just spend the better part of a couple of weeks isolating a real hair-puller. This applies to trucks running OS 12628954, affects LMM's from 2007-2010 (verified)
Condition: Setting 1501 EGR Control to 'Disable' has the following effects which seem to manifest themselves after the engine is warmed up or after a prescribed run-time:
• Injection timing surge
• Turbo pressure and vane surge, both on cruise and acceleration
• Intermittent extremely black smoke on shifts (suspect this is the EGR valve physically opening even though my logs do not show it.)
• Intermittent lag on acceleration
What appears to happen is the turbo and injection timing modes seem to cycle back and forth with some kind of phantom EGR mode, causing the surging and intermittent black smoke.
I have several logs that capture the surging condition if anyone wishes to look at them. Originally I backdated a few trucks to one of my older tunes until I had the time to isolate this. I just finished A-B-A testing on two different trucks. I have only used B1501 recently, most of my LMM tunes disable the EGR with the original methods - setting B1502-1506.
Bottom line - leaving B1501 in stock position 'Enable' will solve a number of phantom problems with LMM tuning.