Haltech HT-186337 Quick Start Manual page 5

SENSORS AND ECU LOCATION
Air Temperature Sensor
An air temperature sensor is a crucial component
used in Volumetric Efficiency (VE) tuning to
compensate for changes in air density caused by
temperature variations.
Cold air, being denser than warm air, requires
more volume of fuel to maintain the same air-fuel
ratio. With this information available, the Nexus
ECU can automatically adjust fuel delivery based
on temperature changes using the signal received
from the air temperature sensor.
Air flow
Intake pipe
Example installation location of the included air temperature sensor
Included in this package is an air temperature sensor (HT-010200), which can be wired
using the factory air temperature sensor wiring or a spare AVI or SPI, along with a signal
ground connection available in the 16-pin Auxiliary connector at the rear of the adapter
box. These sensors are not polarity sensitive, so either pin can be wired to either wire.
While many vehicles include a factory air
temperature sensor, it is often located within the
Mass Air Flow (MAF) sensor assembly or integrated
into the intake air manifold. Typically, performance
applications involve the removal of the MAF sensor
or even changing the entire intake manifold. In such
cases, an air temperature sensor (HT-010200) is
provided as a replacement for the factory sensor.
Mounting the included sensor in the optimal
position is crucial to accurately measure the air
temperature entering the combustion chamber.
Typically, a good location is just before the throttle
body and after a turbocharger/intercooler if using
forced induction. It's essential for the sensor to be
in the moving air stream for rapid response times
and to minimize heat soak effects. Caution must be
exercised when mounting the sensor directly into
the inlet manifold, especially at the rear, as this
may lead to heat soak issues, where the sensor
reads the manifold temperature rather than the air
moving through it.
Once a suitable position is identified, a hole must
be drilled and tapped to accommodate the sensor.
A weld-on bung may also be used if necessary.
It's recommended to remove the air intake pipe
or relevant intake hardware when installing the
sensor to prevent metal shavings from entering the
engine.
Air Temperature Sensor
(M14 x 1.5 thread)
Throttle body
AVI or SPI
Signal ground
8
ECU Internal MAP Sensor (4 Bar)
The basemaps provided with this product will
either utilize the factory MAP sensor, if the vehicle
is equipped with one from the factory, or utilize the
Nexus S3/S2 ECU's Internal MAP sensor. You can
check this in the software settings under Sensors
> Manifold Pressure > Wiring > Input Type to see
which one is being used.
If the ECU internal MAP sensor is selected, a
vacuum hose must be connected from the ECU's
MAP sensor barb to a vacuum port on the engine's
Internal MAP
sensor (4 BAR)
ECU location
The factory Mazda MX-5 NB SE ECU is located under
a protective plate on the passenger side foot well.
Removal of the panel allows the installation of this
Haltech Plug 'N Play product. Below is a generic
illustration for reference.
intake manifold. This onboard sensor is a 4 Bar
MAP sensor capable of reading vacuum and boost
pressures up to 43.5 psi. No user calibration is
necessary for this sensor.
Vacuum port
Intake manifold
Vacuum hose
9