2014LTZ-Z71

You are not alone - we should have NEVER traded in our 2002 Avalanche....

Our 2014 5.3 was recently repurchased by GM and had this same problem along with a very long list of other issues. We noticed that our truck surged more often when the outside ambient air temperature was over 90-95 degrees and while it was in the drive position with the brake depressed (like at a stoplight). Another thing we noticed is that the outside air temperature digital display on our MyLink screen would always be reading considerably lower than the real outside air temperature while it was having the surging issues. In most cases our air temperature display would be stuck at 88 degrees or lower even though the outside temperature was around 105+ outside. (Just a shot in the dark here) but from what we have seen, we thought it might be some sort of ECM fuel mixture error going on that takes temperature into consideration but the only thing we ever got back from the dealers mechanic was “no codes, can’t fix it”. Top grade 91, 89, and 87 octane premium fuels had no effect on our particular idle surge problem. Close to the end before the buyback the only thing we found that kept it from surging all the time was to run full tanks of E85 in it. While using 89 or 91 octane gas the engine would try to idle at 500 and then drop down to around 250 to 300 then back up (rinse and repeat) but while we were using the E85 it would hardly drop rpm at all while we were idling at stoplights. At least "in our case" the E85 made it bearable. Hope this helped…