I already told you this in chat.... but I'll write it here! Thanks to behlinla for some of this help and info!!
First, watch trims at idle - you're looking for them to be between -5% to +5% just like Jeff said above. You are looking that they don't go outside of that much during any driving.
If you see the LTFT
much higher than that, then you have a probable vacuum leak. If it's super high (+10 to +25%), especially on both banks, then it's most likely a vacuum leak!
Of course record all that and both banks....
Okay, to test the O2
sensors functioning correctly do this test (thanks behlinla):
Find an empty stretch of road, or somewhere you can do this.... idle for 60 seconds and drive normally around 40mph. We're watching that the O2
sensors are switching correctly. They should be moving from around .1v to around .8v at least every 2 seconds, ideally at least ever second.
Next stop the car, then go ahead and go WOT
all the way through first gear. The trims may drop out to very low numbers for a second, but all 4 O2
sensors should jump up to .9v or so the entire time through WOT
. This means that the correct amount of fuel is being dumped into the motor at WOT
. The duratec really likes to dump a lot of fuel at WOT
. This also shows the O2
sensors are working correctly, the switching is really what you need, but this shows how much fuel you're burning by doing this