With almost every customer conversion, we are asked about the connection
plans for the boost pressure control valve, intake air temperature sensor and a
vacuum plan. So today's blog deals with exactly this topic: How to properly
connect the vacuum lines and the sensors when doing a turbo conversion!
Vacuum lines:
To basically connect the new vacuum lines on the ECU and on the boost
pressure control valve, use two free 4mm vacuum connections on the intake
manifold behind the throttle body (i.e. the side that sits between the throttle
body and the engine). Guide one of the new vacuum hoses through the bulkhead on
the passenger side into the interior and connect it to the control unit's MAP
sensor. You can secure the ends of the vacuum hose to the connections on the
MAP sensor and intake bridge with small zip ties.
The second new vacuum hose on the intake manifold then leads to the boost
pressure control valve at the connection under the electric connector of the
boost pressure control valve. Instead of starting from the intake manifold (if
available on the respective turbo), this can also simply be connected from the
connection to the turbo outlet on the pressure side. This has the advantage that no vacuum line has to
be pulled across the engine bay. So if this vacuum connection is available on
your turbocharger, it can simply be used and the intake manifold can remain
plugged. The vacuum hose can then also be secured on the connections with small
zip ties. Last but not least, a vacuum line between the outlet of the boost
pressure control valve (connector pointing upwards) and the wastegate of the
turbocharger has to be installed. This line can then also be secured with small
zip ties.
Electrical connector
of the boost control valve:
Now we can connect the
boost pressure control valve to the existing wiring harness. Here you always
use the cables of the purge valve in the engine compartment.
MX-5 NA:
Positive supply: white / red
cable of the purge valve
Ground signal: yellow / red cable of the purge valve
MX-5 NB:
Positive supply: white / red cable of the purge valve
Ground signal: green / black cable of the purge valve
MX-5 NBFL:
Positive supply: white / red cable of the purge valve
Ground signal: green / yellow cable of the purge valve
Electrical connector
of the IAT sensor:
Finally, we connect the
intake air temperature sensor to the existing wiring harness. For this purpose,
different sensors are used in the different models, for the cables of which we
use for the new IAT sensor. The cable colors of the MX-5 NA were often swapped,
but we have listed the most frequently used cable colors here. However, it can
happen that the cable colors on your vehicle are different. The pin assignment
is irrelevant here, as the temperature sensor is a simple resistor.
MX-5 NA 1.6L:
Red/green and black wire with additional color (mostly green) of the air flow
meter
MX-5 NA 1.8L:
Red/black and black wire with additional color (mostly blue) of the air flow
meter
MX-5 NB/NBFL:
Use the two cables of the original intake air temperature sensor (on the side
in the air filter box). The original air flow meter is completely omitted here.
You are currently doing a
turbo conversion on your MX-5 and the instructions did help you? Or do you
still have unanswered questions? Just write it in the comments and we'll be
happy to help!
Your SPS Motorsport Team
