I am new to the Gen IV pcms and am working on my first one. Its an 07 Avalanche that has a cam, portwork, headers, cai. Once I got it pretty close so it would start good, rev good and drive good it does some thing a little weird. At an idle in park warmed up, it will have a commanded afr of 13.9 and have a smooth idle, timing is steady, fuel trims at 0, then all the sudden it will turn to a commanded afr of 14.5. Then timing goes erratic with a slight surge, and fuel trims start going negative. Then it goes back to the 13.9 and all is good again. In the past I have only worked on the LS1 pcm and the commanded pretty much stayed at 14.68, I thought the 13.9 was a little rich to be commanding. Other than changing the maf a little and adding air on startup and BAF, the tune is pretty much stock. I should have logged a quicky to show but forgot, I post tune just incase. Thanks for looking!
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