Manuals through 2025 now available!
Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.
LEMON is the spiritual successor to CHARM, I recommend you try it!
Link:
lemon-manuals.la or
lemon-manuals.org.ua
(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)
Or, hide this message:
temporarily or
permanently
Short Term FT
The scan tool displays a positive or a negative percentage. The Short Term Fuel Trim
(FT) represents a short-term correction to fuel delivery by the
PCM. The Short Term FT correction is driven by the fuel control
oxygen sensor voltage. When the oxygen sensor voltage remains less than
450 mV the PCM adds fuel and the Short Term FT parameter displays a positive percentage. When the oxygen sensor voltage stays at more than
450 mV the PCM subtracts fuel and the Short Term FT parameter displays a negative percentage. During an extended idle in high ambient temperatures the Evaporative Emission
(EVAP) canister may purge, causing the Short Term FT to read in the negative range. This is a normal condition. Fuel trim values at maximum authority may indicate an excessively rich or lean system.