Rookie question. I just returned from a trip towing my 8K lb travel trailer. Changes since last time are Bullydog Tuner with IDP tunes, and 4" turbo back exhaust w/4" downpipe. EGT dropped considerably from previous trips and didn't reach 1300 on a very long steep pull. I was running the IDP Street Tune for under 10K lb towing. Something new happened though that I haven't had happen yet. The turbo seemed to "cough", or that is the best I can describe it. I seemed to do it after I let off the accelerator and RPM dropped (one time slowing down for the guy in front of me), and when I went to accelerate again it seemed to cough and shake and sounded like the turbo was puking or coughing. RPM came up and it went away. Happened a couple times during the long pull up the pass. One time I could feel a hard vibration through my foot on the accelerator and it was a slightly different sound, almost like a backfire or something. Turbo was just cleaned, I'm EGR deleted, Garrett Powermax turbo.

Any ideas? Didn't throw any codes and all temps stayed normal.

 

Is the tune written for a Power Max or stock turbo?

 

Powermax specified

 

Clean the MAP and EBP sensors and tubes that feed those sensors, should help. Use weed whacker line to open the tube and make sure the nipples are clear as well.