Pickup Nissan 300ZX Z31

1. Ensure ignition timing and idle speed are correct. Turn ignition off. Remove idle CO adjust kit from rear of ECU.
2. Unplug idle CO adjust kit harness connector. Drill and tap a hole in adjusting hole seal plug.
3. Start engine. Warm to operating temperature. Insert CO probe more than 16" into exhaust pipe and check CO reading.
4. Adjust idle CO level by turning variable resistor of CO adjust kit so Green and Red inspection lamps on ECU flash almost simultaneously. Also, check CO level on meter.
5. If lamps flash as specified and CO level is correct, turn off engine. Install new plug in idle CO adjust kit. Replace kit on ECU. Connect all hoses and wiring.
6. If CO level is incorrect, check if output voltage changes while turning adjustment screw. See IDLE CO ADJUST KIT INSPECTION.
7. If output voltage will not change, replace idle CO adjust kit if defective. If output voltage changes (idle CO adjust kit functioning correctly), replace venturi chamber of throttle body.

Scheme 4

1. Variable zone between maximum and minimum level is covered by 22 revolutions of screw of idle CO adjust kit. If screw is outside variable zone, measure voltage between terminal No. 1 and ground with engine running. (Scheme 4)
2. Multiply voltage at terminal No. 1 by.37. This value is the Vco.
3. Measure voltage between terminal No. 2 and ground. If voltage at terminal No. 2 is equal to or more than Vco, turn adjustment screw of variable resistor counterclockwise.
4. If voltage at terminal No. 2 is less than Vco, turn adjustment screw of variable resistor clockwise. Replace unit if it can not be adjusted.

IDLE SPEED SPECIFICATIONS

IDLE CO LEVEL SPECIFICATIONS

Scheme 5

1. Place transmission in Neutral and turn all accessories off. With engine idling, disconnect harness connector at throttle switch on throttle chamber. Using an ohmmeter, ensure continuity exists between terminal Nos. 29 and 30 (18 and 25 for 300ZX) on switch. (Scheme 5) Disconnect auxiliary air valve harness. (Scheme 5): Throttle Valve Switch Location On EFI Models (To Adjust, Loosen Adjusting Screw, Rotate To "ON" Position At Idle Speed)
2. Loosen adjusting screw on switch. Hold engine at speed shown in THROTTLE SWITCH SPEED chart. With ohmmeter leads connected to terminal Nos. 29 and 30 (18 and 25 for 300ZX), turn switch until it is "ON". Tighten adjusting screw. Turn ignition off and remove ohmmeter. Reconnect harness at switch and air valve.

THROTTLE SWITCH SPEED