Lancer412

Update. Had it dyno tuned and all is good. Runs better than it did when it was new. Still say GM's programming was the problem.

I have a 2009 GMC Sierra 1500 with a stock 5.3L and the truck has 211k miles. The engine was replaced with a Jasper engine 1000 miles ago, that has the AFM deleted, and since then I've noticed louder than normal engine noise through the intake while accelerating. Sounds like it has a cold air intake, but its the factory intake and air box. It acts like timing is retarded, yet all is normal on the scanner and no codes generated. I checked the whole intake system for cracks or splits but all is good and sealed. I'm beginning to think it's the programming from GM's latest calibration since I haven't found anything wrong elsewhere. As a tech of 35 years, I'm perplexed and I've even enlisted the help of at least 6 other techs, including the GMC dealer, that just shrug their shoulders after checking it out because they're also perplexed. This is my last resort in an attempt to get to the bottom of this. Any help would be greatly appreciated.