Haltech E8 - Manual (Page 157)

Haltech E11/E8 Instruction Manual
generate a voltage similar to figure E.5 on the positive wire. The amplitude of the signal will vary with the
speed at which the ferrous metal passes the pole piece. At low speeds the signal may only be several
hundred millivolts, but at high speeds it could rise to 20 volts or more. The sudden drop in the signal from
positive to negative seen in figure E.5 corresponds to the metal being directly in line with the sensor. As
can be seen, the signal is not a square wave required by the ECU, and at low speeds the signal amplitude
is too low.
The voltage input of the reluctor adapter must first go to a positive peak, which arms the circuit. When the
signal rises to approximately 70 - 80% of the peak value the reluctor adapter will generate a falling edge,
and when the signal crosses zero volts a rising edge triggers the Haltech ECU. If the wires are reversed
and the signal goes negative first, the Reluctor adapter will generate a pulse but it will NOT trigger the
ECU correctly resulting in incorrect ignition timing.
Standard Trigger
The simplest form of trigger pattern is what we refer to as Standard Trigger. With standard trigger, there is
a synchronising pulse that precedes each ignition event for the engine. For a 4-cylinder engine, the trigger
signal will have 4 pulses with each pulse occurring before the spark event. Typically, this angle will be 65°
to 70° BTDC. Ignition events typically occur at less than 45° BTDC.
The standard trigger pattern can be as simple as one pulse per ignition event on the trigger channel only,
but there are variations on this trigger that allows for varying degrees of engine synchronisation to allow
for more complex fuel and ignition outputs. The 3 variants of standard trigger are as follows:
Standard with No Home signal – This type of signal gives only a single pulse per ignition even on the
trigger channel. This type of trigger signal is suitable for running distributor ignition systems only. With this
information, the ECU only knows when a piston is approaching TDC. It does not know which piston, but
the distributor will distribute spark to the correct cylinder. The only possibility for injection mode is
multipoint injection where all injectors fire at the same time.
Standard with Home on the Crank – This type of signal uses a single pulse per ignition event on the
trigger channel, but supplements this information with a home pulse just before the pulse for cylinder 1
approaches TDC. Since the home signal comes from the crank, there is insufficient information for the
ECU to determine if the crank is at TDC compression, or TDC exhaust. As a result, the most complex
ignition mode that can be used is Wasted-Spark ignition mode where a spark always fires as a piston
approaches TDC of either stroke. The best fuel mode that can be used is “Semi-Sequential” injection
where half of the fuel pulse if fed to the cylinder on the correct cycle of the stroke (i.e. Just before or during
the intake stroke) and half the fuel is injected at the wrong half of the cycle (i.e. During the compression
stroke). Semi-sequential injection has the advantage that at least half of the fuel is injected on the correct
part of the cycle leading to better atomisation than with multipoint. In addition, the fuel is always injected in
the same positions for every cylinder, thus leading to smoother, more even running of the engine.
Standard with Home on the Cam – This type of signal gives a single pulse per ignition event on the trigger
channel, but supplements this information with a home pulse just before the pulse for cylinder 1 as it
approaches TDC of compression. With this information, the ECU knows exactly the position of each
piston and which part of the 4-stroke combustion cycle that it is on. With this information, direct-fire multi-
coil ignition is possible along with Sequential fuel injection.
If the vehicle that you are fitting a Haltech ECU to does not have one of the supported triggers, then
fitment of a Hall effect, standard trigger setup is quite simple and straightforward. Contact Haltech for
Copyright © Haltech 2008 Page: 157
WARNING
An incorrectly wired reluctor will retard ignition timing as RPM increases or
generate multiple triggers. Incorrect wiring of a reluctor trigger can cause major
problems. If you are using a reluctor pickup ensure that they are wired with the
correct polarity .