02 S60 STFT & STFT; What do these 2 graphs mean???

[sergio]

.


1
Normally STFT does wobble up and down. Not around 0% but in the negative zone
But sometimes it stays dead stoned, like this time.

2
The LTFT seams always dead at about 12% from the 1st second engine starts to the last when it stops. Whether idling, running, accelerating or decelerating; suddenly or slowly


Can anyone translate / interpret what these particular graphs are trying to tel me?

Please?

Why both show straight lines ???



.

[mrbrian200]

Here's a pretty good explanation of short term vs long term fuel trims:

http://www.easterncatalytic.com/educati ... ostic-tool

Thought not mentioned in the article, in my experience a malfunctioning electronic throttle body can throw fuel trims out of whack as well. But you'll want to first look for air leaks/loose hose connections, then, the list of items they talk about under 'running too lean' toward the end of the article to correct a positive LTFT you are seeing that is probably the greater concern over what STFT is showing at any given moment.