Quote:
Originally Posted by Koa
not true, STFT and even LTFTs will vary above and below 0% if the system is operating as normal to account for variances in fuel quality and atmospheric conditions above what the car was tuned for
all your other advice is sound  |
we have to know what is hes ltft . should ecu try correction fueling maps
it happens to me , one of my DI failure by reduce inject fuel from the DI.
so that will insurance fuel trim.
ok for example.
if the car @ 3000 RPM with 14.7 AFR and 0% LTFT and 20% inj duty each . THAT means 14.7/4 inj = 3.675 AFR each .
if one of inj failure and have 3.0 AFR with same duty and RPM (engine load).
so then the total of AFR is 3.675*3 inj + 3.0*1 inj =14.025
the ECU try correct the fuel by adding fuel to all 4 inj until it stop at 14.7 AFR TOTAL .
SO ECU ADD FUEL BY THIS (14.7 AFR - 14.025 AFR) / 4 inj = 0.16875 AFR insurance each inj
it will be ( 3.675 AFR + 0.16875 AFR ) * 3 + (3.0 + 0.16875 AFR) = 11.53125 + 3.16875 = 14.7 AFR (ecu happy )
but the LTFT will be (0.16875 AFR /3.675 AFR) * 100 = 4.591%
so the LTFT will be +4.591%