decreased. Increase the idle jet 4 to 6 pulses higher when the engine is lean. The lambda should
now read on the rich side. Too rich will also cause the engine to lose RPM’s or the vacuum bar to
move to the right. Increase the mixture to see where is the furthest point to the right on the lambda
bar to determine the sensor maximum. Always tune to stay below this maximum value. If you don’t
see movement on the bar it means you are over the sensor limit and you will only waste fuel and
rob your engine of power. If the lambda does not react as explained it may be damaged or not
wired correctly. See lambda wiring in the manual.
Now you need to get a setting for the main jet to get a baseline fuel setting under normal load
conditions. Firstly set the main jet to a value where you can drive with the vehicle. Zero the
vacuum map in the middle so that no compensation is taking effect. Go on the open road and
cruise at 120 km/h. Try to get a flat road where you can have a constant supply of fuel to the
engine. Also aim to have the Map sensor value in the middle of the graph on the vacuum map.
Adjust the main jet slider for enrichment of 0.45V on the lambda slider bar. If the engine works
hard like for an elevated 4x4, you may not reach 120km/h under half load.
If you already have a pre loaded map, your vehicle should be running fine. You still need to adjust
the main jet because fuel pressure and air resistance between vehicles differ causing a custom
setting for each. Leave the compensation as it is and only adjust the main jet as above. If the main
jet is adjusted, you may need to correct the idle jet afterwards, as it uses the main jet value in its
calculations. For turbo cars you may need to work on different loading to get the desired setting. If
you started with a small main jet setting, your vacuum graph will tend to sit above the zero line.
When you finished tuning the ECU, the vacuum graph should sit around the zero line.
During full load conditions, always stay just below the maximum mixture on the lambda slider. If
you are on it you will not see if you are over it. Do not go lean at any stage, as this may damage
your engine. Setting full load maps always monitor the lambda sensor and the moment you go
lean, back off the throttle and adjust the maps and try again. During normal cruising, stay in the
changeover region, 0.45 volt or 14.7. Light cruising may go left in the lean mixture. Do not worry
as there is too little heat to destroy the valves. Remember that a lean mixture will lose power more
rapidly that a rich mixture. So you can use this feature for normal cruising to check if you are in the
ball park with fuel. By pressing the page up or down button, the slider will jump by 10 each time.
When driving, you can page down to see if you are not too rich on the mixture. Leaning the fuel
out by 10 to 20 should be felt by losing power. The lambda should also go lean if it is not already
lean. Remember the value of the slider and always come back to it. Rather adjust the dots on the
graph in that region.
For turbo cars ensure that your mix is on the rich side at WOT. Also ensure that timing is below
24°BTDC. Now follow the steps setting up your ECU.
9.4.1 Setting the Main Jet
Go on the open road and cruise in top gear around 120Km/h. Look for a flat road where cruising
can be consistent without hills or overtaking. Your total vacuum range can be divided into two and
use this setting if you are on a Dino. Drag the slider up or down to increase or decrease fuel till the
desired air/fuel mixture is obtained. Normally around 14.7 or 0.45Volt on the lambda slide bar.
Now memorize this setting as it is handy to use the main jet for tuning. Always come back to this
setting as the rest of your tuning is calculated around this baseline fuel setting.
9.4.2 Setting the Idle Jet
Stop the car and let it idle in park or neutral. Ensure the graph around the vacuum bar is flat.
Adjust 2 dots on each side at the same level. They may be at around 10% above the zero level
since idling requires a richer mixture. Adjust the Idle jet to get the desired mixture. If the lambda
indicates a lean mixture make it richer by increasing the value. The mixture should be as rich as
WOT mixture. If you step it down 4 to 6 numbers you should be able to see the vacuum bar move
to the right. Too rich a mixture will also cause the bar to move to the right. Lean it out a bit.
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