evolizzee
Member
Anyone else monitor their long term fuel trims? I seem to have noticed a trend and I’m not sure if it’s typical across the board for the 5.7, or not. When at idle, my LTFTs are 0.0 or close, all the time. However, the faster and faster I cruise down the highway; the 02s “appear” to notice a leaning out condition. 50mph ≈ +5%, 70 ≈ +9%, 90mph ≈ +11%. While in open loop, the ecu seems to be constantly trying to richen things up. I’ve added some flow mods to the engine but I would think the tune would help calibrate the ECU to compensate for those modifications to keep trims as close to 0 as possible during open loop conditions. That is, as long as all mechanical and sensor components are operating nominally. I don’t get concerned with LTFTs that have a deviation less than 10%. But over 10% and I start thinking about looking for a mechanical, electrical, or calibration issue… or adding in a wideband to see what closed loop conditions yield.
