Mazda RX-7 On-Vehicle Adjustments: idle speed, ignition timing and more

Mazda RX7 1993-1995 FD3S

ENGINE MECHANICAL

Before performing any on-vehicle adjustments to fuel or ignition systems, ensure engine mechanical condition is okay.

IGNITION TIMING

Before adjusting ignition timing, warm engine to normal operating temperature. Turn off all accessories. Place transmission in Neutral (MT) or Park (AT). Ensure idle speed is correct. If ignition timing is not within specification, loosen distributor or crankshaft position sensor lock bolt. Rotate distributor or crankshaft position sensor until timing marks are aligned. Tighten lock bolt.

1. Connect Diagnostic Tester (49-B019-9A0) to data link connector. Set SYSTEM SELECT to position 1 and TEST SWITCH to SELF-TEST, or connect jumper wire between data link connector terminals TEN and GND. See Fig. 1 .
2. If ignition timing is not within specifications, see appropriate articles:

• H - TESTS W/O CODES
• G - TESTS W/CODES

Disconnect diagnostic tester or jumper wire from data link connector.

Fig. 1: Identifying Data Link Connector Terminals

Fig. 2: Locating Ignition Timing Marks (Typical)

IGNITION TIMING SPECIFICATIONS (Degrees BTDC @ RPM)

• Leading, Connect jumper wire between terminals TEN and GRD of data link connector.
  • MT: 5 @ 720
  • AT: 5 @ 720
• Trailing, Connect jumper wire between terminals TEN and GRD of data link connector.
  • MT: 20 @ 720
  • AT: 20 @ 720

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IDLE SPEED AND MIXTURE

Idle mixture is not adjustable. If idle mixture is incorrect, see Fig. 1 . If ignition timing is not within specifications, see appropriate articles:

• H - TESTS W/O CODES
• G - TESTS W/CODES

1. With engine cold, ensure roller near screw "B" is centered on fast idle cam. See Fig. 3 . Warm engine to operating temperature. At 130-149°F (55-65°C), wax rod should extend fully and fast idle cam should separate from roller. If wax rod does not operate as described, replace wax rod or adjust separation point.
2. Turn screw "B" until separation point is as described in step 1). See Fig. 4 . To adjust fast idle cam opening, turn screw "A". U sing screw "A", align points on fast idle cam with roller at corresponding temperature.

FAST IDLE CAM OPENING SPECIFICATIONS

• A: -5 (-20) °F (°C)
• B: 32 (0) °F (°C)
• C: 77 (25) °F (°C)
• D: 140 (60) °F (°C)

Fig. 3: Checking Fast Idle Cam Separation



Fig. 4: Adjusting Fast Idle Cam Opening

DASHPOT

Before adjusting dashpot, warm engine to normal operating temperature. Turn off all accessories. Place transmission in Neutral (MT) or Park (AT).

Operate engine at 4000 RPM. Slowly decrease engine RPM until throttle lever contacts dashpot. If engine RPM is not as specified when throttle lever contacts dashpot, loosen lock nut and adjust dashpot as necessary. Tighten lock nut.

• RX7 1993-1995: 2600-3000 RPM

IDLE SPEED

Before adjusting idle speed, warm engine to normal operating temperature. Turn off all accessories. Place transmission in Neutral (MT) or Park (AT). Throttle adjusting screw is preset and if adjusted, will adversely affect engine performance.

1. Connect Diagnostic Tester (49-B019-9A0) to data link connector. Set SYSTEM SELECT to position 1 and TEST SWITCH to SELF-TEST, or connect jumper wire between data link connector terminals TEN and GND. See Fig. 1 .
2. Connect tachometer to data link connector terminal IG (-). If idle speed is not within specification, rotate air adjusting screw on throttle body. See Fig. 5. If idle speed is too high with air adjusting screw closed, loosen lock nut and turn throttle adjusting screw. Disconnect diagnostic tester or jumper wire from data link connector.

Fig. 5: Adjusting Idle Speed

IDLE SPEED SPECIFICATIONS

• RX7 1993-1995
• M/T RPM: 720
• A/T RPM: 720

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THROTTLE POSITION (TP) SENSOR

Throttle adjusting screw is preset and if adjusted, will adversely affect engine performance.

THROTTLE POSITION (TP) SENSOR VOLTAGE INSPECTION AND ADJUSTMENT

1. Turn ignition switch to OFF position. Connect Harness Adapter (49-T018-902) and Signal Monitor (49-9200-162A) to ECM/PCM. See Fig. 6 . Set signal monitor to specified ECM/PCM terminal. Turn ignition switch to ON position.
2. Manually rotate throttle linkage and check voltage readings. If voltage is not as specified, close throttle. Loosen TP sensor screws. Rotate TP sensor until voltage indicates as specified. Tighten TP sensor screws. Turn ignition switch to OFF position and disconnect test equipment. Reconnect ECM/PCM connector.

TP SENSOR VOLTAGE

• Wire Color To Ground
  • Green/Red (3F)
    • Closed Throttle Volts: .75-1.25
    • WOT Volts: 0.1-0.7
  • Black/Green (3G)
    • Closed Throttle Volts: 4.8-5.0
    • WOT Volts: 4.2-4.6

Fig. 6: Checking TP Sensor Voltage Signal



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Mazda RX7 1993-1995 FD3S

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