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III. Installing the Nitrous Purge

With the fuel supply line connected (rear) we can get the nitrous feed and purge line hooked up. Here we are installing the purge adapter fitting, supplied with the ZEX purge kit. We'll attach a separate -3AN braided line from the elbow fitting to the purge solenoid.

We mounted the purge solenoid right behind the radiator support so that the oulet line can be directed outside the vehicle. The braided line from the adapter elbow is connected to the inlet port on the solenoid.

The nitrous purge exits through the supplied hardline. The optional LED illumination module is mounted to the end of the hardline as mocked up here. Where you choose to mount the purge is a matter of taste and how you want to show it off.

We found a suitable and relatively inconspicuous place under the front bumper to located the purge exit and LED. When the nitrous line is purged the LED will light up the exiting gas cloud - hopefully to the ammusement of spectators.

Wiring the purge solenoid and LED is quite simple and does not involve any wiring to the management unit or rest of the system. Ground either one of the wires from the solenoid along with the black wire from the LED module. Using a bullet connector, splice together the other lead from the solenoid with the red lead from the LED as shown.

The ZEX kit comes with plenty of 18ga. wire to get everything routed where you want. Run a length of wire from the purge solenoid hot wire, through the firewall, and up to one of the terminals on the supplied push-button purge switch. Connect the other terminal to a 12V source (the solenoid will draw 10amps) using the inline fuse included in the kit.
IV. Wiring the System

The beauty of the ZEX system is in the simplified wiring. You only need to deal with three wires, and one of them is ground. The red will route to the main system activation switch. The white is the wide-open throttle trigger.

The white lead from the nitrous management unit needs to connect to the signal wire on the throttle position sensor (TPS). We checked the Ford Fuel Injection book by Probst to figure out the green wire on the sensor plug carries the TPS signal.

Using the "t-tap" connector we spliced the white wire from the ZEX unit into the green TPS signal wire.

We can verifiy the correct wire from the throttle positon sensor by checking voltage (key on). With the throttle closed the voltage will be just under 1V. The voltage should rise up to 4.5V as the throttle is opened to maximum. The other two wires in the sensor will read constant voltage.

The hot leads for the management unit and the purge solenoid are routed along the valve cover and throug the firewall to the switches.

Connect the red lead from the nitrous management unit to the un-fused lead from the toggle switch. The fused side connects to a 12V source (key-on ideally.) The system will draw 10 amps so tap into a suitable supply.
V. Programming the Activation Switch

Once the system is wired up we can program the activation switch that is built into the ZEX nitrous mangement unit. It's important to perform this step with the nitrous bottle valve shut.

With the key-on (engine does not need to be running) toggle on the nitrous arming switch.

Press and release the programming switch on the nitrous mangement unit. The indicator bulb will turn to solid red, indicating the activation swtich is in "learn" mode.

After releasing the programming switch move the throttle to wide-open position and hold for 10 seconds then release. Go back to the nitrous management unit, the LED should be flashing red to green to off indicating it has learned the TPS voltage curve.

Turn the activation toggle switch off and then on again. The LED on the management unit should be steady green. Without opening the bottle you can test for proper function of the activation switch by pressing the pedal to the floor and listening for the solenoids to click.

The final step, once you have completed the wiring, is to open the valve on the nitrous bottle and check the system for leaks. A 10lb nitrous bottle usually costs between $3 and $5 a pound to fill, and will last about 8 1/4 mile passes before you need to refill. Operate the nitrous at 900-1000 psi for best results. If you need to bring the pressure up place the bottle in the car and turn the heater on. Never apply a torch or flame heat to the bottle.
   

 

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A couple taps of the purge switch and the nitrous line is cleared of any air and ready to be fired. The blue LED illuminates the nitrous purge cloud and serves as a visible warning to any would be competition.
 

We took the car to the track for some quick testing with the nitrous. We limited the nitrous jetting to 75 horsepower because we did not yet have the chip reburned for the new mass air meter and felt the engine was running slightly leaner than we'd like.

Track Results
  60 ft.
ET
MPH
N/A 1.65
11.87
116
Nitrous 75HP 1.71
11.42
119
Nitrous 75HP 1.66
11.38
120

Our best ET naturally aspirated was 11.87 on a mediocare 60ft. of 1.65 seconds (worn out ET Drags slicks.) After warming the bottle in the cab of a friends truck with the heater blowing we obtained a bottle pressure of 850psi and made a couple of passes. We saw a gain of about 5 tenths and 4 mph. There should be close to a full second with a 100 horsepower shot and bottle pressure closer to 950psi. We'll be back to the track shortly for more testing once our chip arrives.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Contacts:

ZEX
3418 Democrat Road
Memphis, TN 38118
1-888-817-1008
www.zex.com

Professional Mass Air Systems

720 Terminal Rd
Lansing, MI 48906
517-327-3900
www.massairsystems.com