MR2 Turbo Aquamist Installation: Wiring

Overview	Water Pump	Water Line	Parts List

Find a suitable location on the front firewall inside the cargo compartment or near the front fuse box to attach the relay supplied with the Aquamist kit. When you have found a suitable location for the relay, drill a hole and use the supplied self-tapping screw to secure the relay in place. Find a bolt near where the pump harness enters the cargo compartment near the right headlight and cut the heavy green wire on the harness so that it will just reach the bolt. If there is not enough wire left over from what you cut off to reach from the same bolt to the relay, find a length of similar gauge wire that does reach. Crimp and solder an eyelet connector of a suitable size to both the green wire from the pump harness and the other wire that reaches to the relay and ground it to the chassis with the bolt. Crimp and solder a spade connector to the other end of the wire and slide it onto the terminal labeled 85 on the relay.

Run the heavy gauge red wire of the pump harness to the relay and cut the wire leaving just enough length to reach the terminal labeled 87 on the relay. Crimp and solder a spade connector to the end of the red wire and slide it on the 87 terminal. If there is not enough of the red wire left to run from the relay to the positive battery terminal, find a length of similar gauge wire that does reach. Crimp and solder a spade connector onto one end of the wire and slide it onto the terminal labeled 30 on the relay. Solder and shrink wrap one of the wires on the fuse holder supplied with the Aquamist kit to the other end of the wire. Crimp and solder a suitable eyelet connector onto the other fuse holder wire and attach it to the positive battery terminal.

Unbolt the metal panel that holds the front fuse box firmly against the side of the front cargo area and detach the bottom cover from the fuse box (there are plastic tabs inside the fuse box that hold the cover--you don't need to yank too hard--be patient). Inside, locate one of the black-orange wires that run to the various relays. Carefully cut one of these and solder and shrink wrap it back together attaching the wire that you cut off from the wiring harness when you were installing the Aquamist pump. This wire will now be energized when the ignition switch is turned to "ON." Reassemble the fuse box and reattach it back in its original location being careful to run the new wire down through the stock wire bundle. Measure out how much wire you need to reach the relay and cut off any excess. Crimp and solder a spade connector to the wire and slide it onto the terminal labeled 86 on the relay.

Solder and shrink wrap the thin wire on the Aquamist pump harness to the wire that runs back to the engine bay. This wire will control the Aquamist pump. While the wire is pulled to ground, the pump will not run. If the wire is allowed to float or is pulled to positive voltage, the Aquamist pump will run. In my particular installation, I use a general-purpose output on my EMS to run the pump whenever the pressure in the intake manifold rises above a present amount. In most installations, you will use the pressure switch supplied in the Aquamist kit to control the pump.

The pressure switch supplied with the Aquamist kit needs to be installed near the intake manifold on the rear firewall between the engine bay and the trunk. Open the trunk and pull back the trunk liner. Find a suitable location for the pressure switch near the plastic connector labeled "DIAGNOSIS" and drill an appropriate hole for the pressure sensor bracket. Bolt the bracket in place with the supplied hardware. Cut the hose going from the intake manifold to the turbo pressure sensor (the little black box next to the plastic connector labeled "DIAGNOSIS"). Using a 6mm tee, connect the hose back together and use a short piece of 6mm hose to connect the tee to the Aquamist pressure sensor. There are two terminals on the pressure sensor. Connect one terminal to chassis ground using a short piece of wire with a spade terminal crimped and soldered on one end and an eyelet connector on the other end grounded to the chassis on a suitable bolt. Route the wire coming from the front of the car to the pressure sensor. Crimp and solder a spade connector to the wire and slide it on the second pressure sensor terminal. Put the trunk liner back in place. Put the plastic cover and the spare tire back in the front cargo compartment.

Reconnect the battery terminals to the battery. Put the 15 amp fuse provided with the Aquamist kit into the fuse holder. Turn the ignition key to "ON." Prime the system by pulling off one of the terminals from the pressure sensor for 3 to 5 seconds until you hear water spraying into the intercooler pipe. Do not allow too much water to spray, or it will be hard to start the engine.

The pressure sensor is adjusted at the factory to run the Aquamist pump whenever the manifold pressure reaches and exceeds 10 psig. There is an adjustment on the sensor that allows you to raise or lower this point. Adjustments to this and to boost, fuel and timing should be done carefully and by an experienced individual to prevent engine damage. Be sure to check the fluid reservoir level regularly to prevent damage to the engine or the Aquamist pump from running dry.