Haltech E8 - Manual (Page 90)

Haltech E11/E8 Instruction Manual
bar due to the interpolation between the two bars.
If you are experiencing difficulties maintaining air to fuel ratio at full throttle, it may be necessary to use the
Full Throttle Map to set the full throttle mixtures. The Full Throttle Map 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 15500
rpm.
Figure 94 - Barometric Pressure Correction Map
Throttle Pump Maps
The manifold pressure sensor used with the ECU is very fast. It can respond much faster than is required
to track any sudden changes in load on your engine. However, the manifold pressure seen at the sensor
input may not change as quickly as what is seen by the inlets to the combustion chamber, due partly to
the length of the connecting pipe. This delay can be reduced by keeping the length of vacuum hose
between the inlet manifold and the pressure sensor as short as possible. Even with very short vacuum
hose lengths there may still be a lag between a transient pressure occurring and the pressure reaching
the sensor.
Further, when the throttle is cracked open, the sudden change in pressure forces fuel out of atomisation
and onto the manifold walls, so it fails to enter the combustion chamber properly atomised, and the engine
hesitates. This can be corrected by adjustment of the Throttle Pump parameters.
To overcome any lean out during sudden throttle movement, the Haltech system uses a throttle
accelerator pump function. This function delivers extra fuel during sudden throttle movements. The
Throttle Pump is accessed from the Maps Menu.
The throttle pump values should be set up after the fuel and maps are correctly tuned for steady load
running. Attempting to smooth out engine transients before the fuel maps have been optimised for steady
state running may become confusing. The throttle pumps 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.
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