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Re: 04 F150 5.4 runs lean at idle
Posted to Technical Discussion Forum on 1/17/2025

IF ST & LT fuel trims are very high at idle but go down toward 0 under load, then I would be looking for a vacuum leak.

What does MAF read in g/sec at hot idle? I usually expect to see around 1.0 g/sec per liter engine displacement at around 650RPM. Low read... Login to read more.