1. The TPS % must be below this value. Set a value small enough to
activate when the throttle is released. If no TPS are installed, uncheck the TPS under active
sensors. Then this feature will only work with the next 2 functions.
2. The vacuum signal must be lower than this value to activate the feature.
Set a value just smaller than neutral idle vacuum at normal temperature.
3. The RPM’s must be higher than this value. Set this value to around 500
RPM higher than idling.
4. There is a dead band implemented in the calculations to prevent hunting. Try to find the best
setting which brings the fuel back the moment the engine goes from negative to positive force
on the drive train. This will prevent jerking when the engine comes to life.
9.4.6 Cold Start Setting
First finish the normal tuning of the engine. The main jet setting will affect this setting as well. For
cold starting and running the engine requires a richer fuel mixture and extra air flow. On certain
engines it may require as much as 50% enrichment on a cold day. Otherwise it will not have
enough power to run.
1. Let the engine cool down overnight. Go to the correction maps. The bar for water temperature
should indicate the outside temperature. If it is out of calibration it is not critical. Normally it is
calibrated to be accurate around working temperature. As long as the sensor follows a
constant graph you can still effectively set up cold starting.
2. Start the engine and decrease the dot on the right hand side of the temperature bar. If you hear
the engine loose RPM or the vacuum signal increase (move to the right), raise the dot with 3%.
Wait till the temperature increase and pass over to the following dot. Do the same here. Keep
on till the engine is on normal operating temperature. At around 60°C the correction map
should be zero if the calibration is correct.
3. A test to see if the mix is correct, is by pressing the accelerator pedal in not too fast, to see if
the engine has a flat spot. If so increase the dot slightly.
4. Remember you may see black smoke but it is normal for a cold engine as it requires a lot of
fuel to run.
5. If the engine has idle control, the ECU will raise the idle set point with 100RPM’s for every 19%
of fuel enrichment. This means that you don’t have to add extra air to raise cold RPM’s.
6. If the engine does not have idle control, you can open a solenoid air valve to the intake by
using one of the GP outputs. This way the engine will idle a bit faster till it reaches a certain
temperature and switch the valve off.
7. The ECU will also lengthen the prime pulse during starting by the same % that the bar is set at.
9.4.7 Air Temperature Compensation
Not all cars or engines have air temp sensors or use this to determine fuel mixture. However is
can be added and used effectively. It is however difficult to tune as you need controlled
environment to do so effectively. When air is cold it is thick and the volume is greater. Thus it
requires more fuel. When hot the opposite happens. If the engine is tuned on a cold, you can save
fuel on a hot day, by leaning out the mix till is correct again. On the other way round, you may run
lean which is dangerous. So to set this you must look at the mix when conditions are changing.
Set the dots on the graph as they change. Do little changes at a time and get to know you lambda
signal very good.
The same happens with timing. The colder the engine the slower the timing must be. So a hot
engine tends to detonate. Here you can retard the timing slightly till detonation disappears.
9.4.8 Battery Voltage Compensation
Battery voltage has an influence on the opening and closing time of the injectors. This will make a
deviation in the fuel quantity especially at high RPM’s. This is also very difficult to adjust. One
advantage is that when cranking the volts will drop quite a lot which make this map ideal to add or
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