senicalj4579

iTrader: (41)

I noticed on the last 3 gas tank fillups the LTFTs will go anywhere from -10 and about -20. I thought it was just a missreading but it dose it everytime after I fill the tank. Is this common after filling up? Why does it do this?

JS01

iTrader: (10)

The fuel that comes out of the ground is cool, it'll do this until it warms up to ambient.

jbrockwell

iTrader: (2)

For those reading this 6 years later: The basic idea is that the evap system pulls the gas fumes from the fuel tank (charcoal canister) into the intake manifold to be used in combustion. If for some reason too much gas vapor is being pulled into the intake manifold, the fuel injectors won't be able to slow down enough to compensate, causing the car to run rich (negative LTFT's).

This obviously shouldn't normally happen but slight issues with the evap system can cause this. No serious harm is being done.

cheep

Very late to the table...
possible flooding charcoal canister during fill up.