SM4 Manual
by
MRM-Racing
V3.0
31
Best practice in calibrating fuel for the different zones:
The startup zone and the forbidden zone must be estimated.
The overrun deceleration zone can be part autotuned, but most often the lowest KPA
cells must be estimated from the neighbour row with higher KPA.
The full power zone must be manual tuned from the log.
The rest of the zones can be partially autotuned.
The spool up transient power zone and the power transient zone partially need to be
estimated.
Sometimes the static load condition is the worst case, and sometimes it is the dynamic,
(transient), load case. The dangerous zones must be well taken care of that they are
tuned for the worst case.
Manual Tuning
This method is done by operating the engine in each Load/RPM cell and experimenting
until the value in the cell produces the correct A/F ratio according to the target values set
in the Target A/F ratio table.
Manual Tuning with the M (maths) Key on the keyboard
This method is done by using the PC data logger to record the air fuel ratios. Then with
the both the data log and fuel table open the "M" key on the keyboard is pressed. A menu
will pop up and ask what the recorded A/F ratio was When you type in the recorded A/F
ratio and press Enter, the software will compare this value to those set in your Target
table and then calculate the correct value for your Base fuel table and automatically set
(tune) that number in the cell on the table.
To use the PC logger press F8 to start recording and F8 to stop. To display the data log
then press F10. To switch between the data log and fuel table press the Tab key. The
"Q" key closes the data log window.
Step1: With the data log displayed move the curser bar (use Left and Right arrow keys)
to any point in the data log where the ghost box on the fuel table matches a RPM and
Load axis.
Step2: Press the Tab key to switch to the fuel table, move the curser so it is also on the
same RPM and Load site as the ghost box.
Step3: Press the M key, a box will appear, type in the recorded air fuel ratio (and Load if
TPS/Manifold mapping), press Ok. The site in the fuel table will now be tuned. Press the
Tab key to switch back to the data log.
Step4: Go to step1 and select another rpm site.
After you have corrected all sites that match go to the Logger menu and Reset the PC
logger. Then record a new data log and repeat the above process. If you thr/manifold
pressure map the engine at WOT (wide open throttle) and use this method only two WOT
runs using the data logger and math key will tune the engine at full power.
