Haltech E6X Manual DOS Version - Manual (Page 70)

E6X Manual
70
CHAPTER 7 THROTTLE EFFECTS
7.1 Throttle Response
Where the procedures described in the previous chapter tune for constant load running, the
functions outlined in this section will improve the throttle response of your engine.
The manifold pressure sensor used with the E6X is very fast. It can respond much faster than
is required to track any sudden changes in load on your engine. The manifold pressure seen at
the sensor input does not change as quickly, due partly to the length of the connecting pipe.
This can be improved 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 Fuel Maps and Set-up Menu.
Six single bars will appear on the screen. The two bars on the left are used below 1500 rpm.
The two bars in the middle operate between 1500 and 3000 rpm and the two bars on the right
are used above 3000 rpm. These bars set the amount of extra fuel that will be added to the
current fuel value during a sudden change in throttle. This extra fuel is added progressively as
the throttle movement continues.
The increase bars determine how much extra fuel the engine gets when you open the throttle.
Once the throttle movement stops the extra fuel value decays at a rate set by the sustain bars.
This feature is used to allow the engine to catch up to the transient that has occurred and,
consequently, its value will be dependent on manifold design.
The heights of the increase bars and the sustain bars are adjusted using the same keys that are
used for adjusting the fuel curve bars. The left and right arrow keys allow you to move from
one bar to the next.
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 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.