Originally Posted by
jarrah
hi guys,
last night was tuning a sierra 2015 on dyno had all types of issues first file I wrote on it truck had like 16 deg of timing in it and I would get wat I command then I adjusted the MAF for AFR err and re ran it on dyno when u step on the throttle for wot timing falls on its face to 0 and ramps to 5 degrees. in the log nothing is taking timing out I kept trying for an hour or so with different changes everytime then I went back to stock tune and started again from there timing was good same tune as the one that pulled timing however no it wont go beyond 15 degrees I even tried In minimum spark to set it all to 24 still get only 15 degrees of timing did anyone have this issue is it an operating system problem it happens only with some of the 2015 not all of them 2014 never had this issue,