Originally Posted by r-clar
What are your sht and LNG fuel trims. They are very important for lean code diagnosis. Ideally both should be about 0%. Usuall long term will be + or minus a few percent and shrt term will be floating around zero. A vacuum leak is usually indicated by fuel trims being high at idle and relatively normal at steady cruise. Any leak after the mass airflow sensor is an unmetered leak.
Freeze frame data for the P0174:
STFT 1: 9.4
LTFT 1: 24.2
STFT 2: 21.9
LTFT 2: 25.0
I noticed at an idle, STFT 2 is cycling almost twice as fast as STFT 1. IOW, #1 may take 3 seconds to from high to low back to high, but #2 may take 1.75 seconds.
I have not looked at Trims while at a steady cruise. I'll do that tomorrow after I build the engine support for the Freestar.
Busy, busy month.