Operation CHARM: Car repair manuals for everyone.
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 Bank 1

Display. shows counts from 0 to 255 and percentage from -100% to 99%. The normal position for the short term fuel trim is 128 counts or 0%. A count greater than 128 or a percentage greater than 0% indicates that time is being added to the injector pulse width, increasing the amount of fuel to the engine to compensate for a lean condition sensed by the bank 1 (rear) HO2S. A count less than 128 or less than 0% indicates time is being subtracted from the injector pulse width reducing the amount of fuel to the engine to compensate for a rich condition sensed at the bank 1 (rear) HO2S.