Haltech F10 - Manual (Page 50)

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steady load running. Attempting to smooth out engine transients before the fuel maps have
been optimised for steady state running may become confusing. The six throttle response bars
should be adjusted by trial and error to give optimum throttle response in each rev range.
Generally, you may not need much above 3000 rpm, but could expect much higher values
below 1500 rpm.
Note that throttle response can also be affected by poor manifold design. If you have designed
your own inlet manifold you may find that although the engine runs well at steady load it
leans out if the throttle is opened suddenly. This will occur if the fuel injectors are poorly
positioned and the fuel is wetting down the walls of the inlet manifold rather than remaining
as a mist.
The final parameter on the Throttle Pump page is the Coolant Factor. Generally, when the
engine is cold, accelerator pump values need to be increased slightly. The F10 therefore
applies a coolant correction to the throttle pump in the same way as it does to the base map.
The Coolant Factor may be set with values from 0 to 4. Setting it to 0 will negate all coolant
correction to the throttle pump. The default setting for this parameter is 0.5.
6.2 Zero Throttle Map
One problem that often occurs with performance engines is rough idling. The manifold
design, cam characteristics, etc. can cause instability in the air flow. This makes fuel metering
difficult. In particular, the M ap sensor often cannot correctly read the manifold pressure, as it
is either non existent, weak, or pulsing too much. In many cases though, once the engine has
some speed, the manifold pressure signal is useable.
The best method of mapping the engine is using the manifold pressure as the load. If in this
configuration idling is causing a problem, the Zero Throttle M ap should be tried. This M ap
maps the fuel delivery at zero throttle below 2000 rpm. There are a few requirements that
need to be met before you can use this M ap. Firstly, your throttle position sensor must be
calibrated properly. Secondly, the M ap relies on there being a consistent air flow at zero
throttle for a given engine speed. That means that devices such as idle speed motors that vary
the air flow at zero throttle will not allow the Zero Throttle M ap to operate correctly.
6.3 Full Throttle Map
The manifold and throttle body design can also cause problems tuning at full throttle on
normally aspirated engines. In some cases, the manifold pressure can reach close to
atmospheric pressure before full throttle is reached. This means that bars close to the full load
bar on the Fuel M aps can interfere with the full load bar due to the interpolation between the
two bars.
If you are experiencing difficulties maintaining air-fuel ratio at full throttle, it may be
necessary to use the Full Throttle M ap to set the full throttle mixtures. The Full Throttle M ap
is activated above the value set in the Full Throttle Threshold in the Fuel Set-up, and has one
programmable bar every 500 rpm up to 16000 rpm.