© 2005-2016 Nira Control AB 103
Preparations before Adjusting the VE
Try to remove the boost pressure completely in order to keep MAP to 100
kPa or less. If you do this you can enter 1.0 in the Lambda Table without
risking engine damage if you avoid full load conditions for extended periods.
For the area of the Lambda Table where the MAP exceeds 140 kPa it’s
advisable to use a lambda of 0.9 or less in order to cool the intake air with
extra fuel and avoid engine damage.
Access to a VE table
Sometimes it’s possible to get a VE table directly from the engine
manufacturer. This makes fuel calibration a much simpler task since NIRA i7x
calculates the amount of fuel to inject based on the VE table. Note that if
camshafts have been changed, the intake has been modified, the exhaust
backpressure has changed or other changes have been made, then the VE
has also changed. If you use one of the VE tables that come with NIRA rk, the
engine will still run, even if the table needs to be adjusted.
VE Calibration when Running the Engine
Start the engine and check that the values from the various enrichment
functions look reasonable. E.g. Choke Enrichment and Acceleration
Enrichment should show reasonable values.
Once the engine has reached normal operating temp, adjust VE such that the
idle is stable and as smooth as possible. Also adjust the lambda table such
that the air fuel mixture is richer at idle.
Then, with the transmission in neutral, slowly rev the engine up to 5 000 - 6
000 rpm in order to find any points in the Volumetric Efficiency Table which
are off. Once you’re satisfied with this step, you can put load on the engine.
In order to find the correct fuel calibration for the engine, you will use both
the VE table and Ignition Table. Hit the F12 key to show both tables
simultaneously.
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