Originally Posted by
Thatwhite5.0
The problem I started the thread on ended up being a faulty brand new Motorcraft plug. Since I did a few things at once, I figured the O2's are brand new Motorcrafts, they got installed an never checked again. If you're having this problem on one side of the motor, definitely swap left and right or try new O2's, I bought some $50 o2 sensors to throw on and my datalogs instantly changed. There are a lot of suggestions in this thread for rich stft.
Also since I'm posting a more recent, since this thread was started, I've went through three sets of o2 sensors due to condensation during very cold ambient temperatures. The o2 has a heated element that gets very hot. If any moisture splashes or hits this element, it will shatter, and will need replaced.
Just to name a few, my bad O2 sensor symptoms were
rich in one bank
which also lead to rich in both banks
idle would be richen as much as -30%
MAF/Fuel trims not taking the adjustments
random misfires
WOT lambda read .69 and .71 in one bank
Fuel source - Open Loop Fault
Fuel Source - Injector Cut
MAF Period would reach as high as 1000us
When adjusting fuel trims based on datalog results, the fuel trims would be out of order.