SM4 Manual
by
MRM-Racing
V3.0
84
The engine load variable used in this table and others that follow below is a function of
throttle position if throttle position is chosen as the primary input and a function of
manifold absolute pressure if pressure is the primary input.
Values in the table are just numbers and do not relate to anything. Increase values to
richen and decrease to lean.
You can modify directly from taken A/F ratio readings by using Manual Tune or by
correcting via a data logged file under mixture tables.
Also see
Cylinder fuel trims,AUX fuel comps,Charge temp estimate, Baro press estimate,
accelerator pumps warm up/cold start compensations.
See
"M1,Base settings" for Fueling overall multiplier and primary fuelling method.
Main Ignition Timing
Base ignition timing table can be setup as throttle position or manifold pressure mapping
on the Y axis. Set this up under "M2 tables axis setup".
When pressure mapping, the LOAD values relate to absolute manifold pressure in Kpa.
e.g:- LOAD 50% = -50 kpa
LOAD 100% = 0 kpa
LOAD 200% = 100 kpa
Values in the table are actual degrees of ignition timing.
Ignition modifiers can be setup
under "Ignition trims".
Make sure ignition advance,
retard limits are not exceeded. (See "M1,Engine settings")
Overrun ign Timing
Engine speed dependent ignition timing calibration for stable combustion under closed
throttle conditions. The adjustment range is the same as the base ignition timing calibration
table above. The table comprises a single row using the same engine speed calibration
sites as the base fuel delivery table above.
Overrun ignition timing can be used to set the engine ignition timing on deceleration.
Adding values similar to the light load values in the main ignition table can soften the
transition from normal running and deceleration. This also can help engine breaking if all
values are set to 0. Overrun ignition timing can have modifiers under "M2, Ignition trims".
Overrun limits can be set under "ECU limits setup" menu.
Injection angle
Injection angle in crankshaft degrees. Value can be from 0 to 717.Default value = 360
degrees .Change this value to find the optimum injection angle.
Calibration of the actual positioning of the fuel injection pulse within the engine cycle,
dependent upon engine speed and engine load. Calibration may be selected at up to 20
engine speed sites and 5 engine load sites with a resolution of 2.8 crankshaft degrees.
Tune example: With the engine idling, hold down the + or - key to increase or decrease the
end angle value at the idle rpm site in the table. Keep sweeping back and forwards from 0
to 720 deg until you find the point where the engine runs the roughest.
There will be two rough points, pick the roughest and make the value in the table 50 less
then this value. The high rpm settings will need a dyno to find the correct value, but as a
guide make them about 40 less then the idle value.
NOTE
If A/F ratio is changing with different air temperatures, see "Change temp estimate"
