Z31 Air Regulator Valve
The Air Regulator Valve is attached to the right side of the intake manifold. This valve is used during cold starts to allow fast idle conditions at startup.
A bimetal element, heater, and rotary shutter are built into the air regulator. When the bimetal temperature is low, the air bypass port is open to allow for fast idle during engine warm-up. As the engine starts and electric current flows through the heater, the bimetal slowly rotates the shutter to close off the bypass port, lowering the idle to normal levels. The air passage remains closed until the engine is stopped and the bimetal cools down.
*WARNING* - Do this modification at your own risk. We Are not responsable for any issues of your own doing.
Common Problems
- High Idle All the time
- Low Idle All of the time
- Vacuum Leak resulting in poor driveability
Troubleshooting
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Disconnect the ECCS 20-pin connector and check voltage between Pin 16 and ground with ignition ON. You should see battery voltage at this point.
- If you do not have battery voltage, check the wiring harness for breaks or corrosion.
- If these tests check out okay, continue to check the air regulator for operation.
- Check for continuity between both pins on the air regulator. If there is no continuity, the air regulator is faulty—replace it.
- Remove the air regulator and visually inspect shutter movement. When the engine is cold, the shutter should be open; when warm, the shutter should close.
- Carefully pry open the shutter to check for smooth movement.
- If any of these tests fail, replace the air regulator.
- Finally, check for any vacuum leaks. The regulator uses an O-ring seal at the manifold and has a vacuum line running to the rear hard lines on the upper plenum. These rubber lines can crack over 30+ years and cause vacuum leaks—replace any lines that show signs of cracking.