Engine Controls - Adjustments Subaru Legacy BC/BJ/BF

ENGINE MECHANICAL

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

VALVE CLEARANCE

Note. All 1.8L, 2.2L and 2.7L engines are equipped with hydraulic lash adjusters. No adjustment is required.

Justy

1. Place cylinder to be adjusted to top dead center position of compression stroke. Insert thickness gauge between valve and valve rocker arm, and check valve clearance. Adjust valves when engine is cold. Use Valve Clearance Adjuster (498767000) and adjust to specification. See «3-CYLINDER VALVE CLEARANCE SPECIFICATIONS»(/subaru/legacy/bcbjbf-1989-1994/remont/adjustments/#engine-controls-adjustments) table.
2. After adjustment, rotate crankshaft several turns and recheck valve clearance.

3-CYLINDER VALVE CLEARANCE SPECIFICATIONS

1. Warm engine to normal operating temperature. Place transmission in Neutral and turn off all accessories. Disconnect test mode and read memory connectors. (Scheme 1)
2. Start engine and check ignition timing. If necessary, loosen distributor hold-down bolt and adjust ignition timing by rotating distributor. Reconnect test mode and read memory connectors.

3-CYLINDER IGNITION TIMING

Scheme 1

Loyale & XT

1. Ensure engine is at normal operating temperature and idle speed is correct. Place transaxle in Neutral (M/T), or Park (A/T).
2. Ensure throttle valve is closed and throttle position sensor is correctly adjusted. Connect 2 test mode connectors together. (Scheme 2)- (Scheme 4).
3. Check ignition timing. If necessary, adjust ignition timing by loosening distributor hold-down bolt and rotating distributor. Disconnect 2 test mode connectors. See 4-CYLINDER IGNITION TIMING table.

Scheme 2

Scheme 3

Note. When checking timing, the CHECK ENGINE warning light will illuminate. This is not an indication of problem. Ignition timing cannot be set if idle contacts in TPS are open and test mode connector is not plugged in.

Legacy

1. Ensure engine is at normal operating temperature and idle speed is correct. Place transaxle in Neutral (M/T), or Park (A/T). Attach timing light to No. 1 spark plug wire.
2. Check timing mark located on crankshaft pulley. If timing is not as specified in «4-CYLINDER IGNITION TIMING»(/subaru/legacy/bcbjbf-1989-1994/remont/adjustments/#engine-controls-adjustments) table, check self-diagnostic system for trouble code(s) and repair as necessary. See G - TESTS W/ CODES article in the ENGINE PERFORMANCE Section.

4-CYLINDER IGNITION TIMING

Scheme 4

1. Ensure engine is at normal operating temperature and idle speed is correct. Place transaxle in Neutral (M/T) or Park (A/T).
2. Ensure throttle valve is closed and throttle position sensor is correctly adjusted. Plug in 2 test mode connector wires. (Scheme 4)
3. Check ignition timing. Timing marks are on crankshaft pulley. If necessary, adjust ignition timing by loosening distributor hold-down bolt and rotating distributor.

Note. When checking timing, the CHECK ENGINE warning light will come on; this is not an indication of problem. Ignition timing cannot be set if idle contacts in TPS are open and test mode connector is not plugged in.

6-CYLINDER IGNITION TIMING

IDLE SPEED & MIXTURE

Note. Mixture adjustment is NOT a part of normal tune-up procedure and should not be performed unless mixture control unit is replaced, or vehicle fails emissions testing. Idle mixture is electronically controlled on fuel injected models; adjustments are not necessary.

COLD (FAST) IDLE

Note. Fast idle on TBI engines is controlled by air control valve. On PFI engines, fast idle is controlled by auxiliary air valve. Adjustment is not necessary on either system.

Justy (Carbureted)

Fast idle is adjusted by measuring throttle valve opening. Measure clearance between throttle valve and bore of carburetor. On M/T models, clearance should be .030" (.77 mm). On A/T models, clearance should be .034" (.86 mm).

Justy (PFI) & XT

1. While slowly returning throttle valve from fully open position, read engine RPM when dashpot lever comes in contact with dashpot.
2. On Justy, ensure engine speed is 2200-2400 RPM when dashpot lever contacts dashpot. On XT, ensure engine speed is 2800-3400 RPM when dashpot lever contacts dashpot.
3. If engine speed is not to specification, loosen lock nut and turn adjusting screw to obtain correct adjustment.

1. Ensure ignition timing is correct. Ensure vacuum hoses, blow-by hoses, rocker arm cover, oil cap and other components connected to intake system are securely attached.
2. Warm engine and oxygen sensor by operating engine at 2500 RPM for about one minute after engine reaches normal operating temperature. Disconnect and plug canister purge hose at check valve (near intake manifold).
3. Connect the test mode and read memory connectors. (Scheme 1) Place transaxle in Neutral (M/T) or Park (A/T) position. Start engine and use idle speed screw to adjust idle speed to specification. See «3-CYLINDER IDLE SPEED SPECIFICATIONS»(/subaru/legacy/bcbjbf-1989-1994/remont/adjustments/#engine-controls-adjustments) table. Disconnect test mode and read memory connector.

3-CYLINDER IDLE SPEED SPECIFICATIONS

3-CYLINDER IDLE MIXTURE

Note. Idle mixture on fuel injected models is electronically controlled; adjustments are not necessary.

1. Warm engine to operating temperature. Connect dwell meter to Yellow/Red wire of Pink 6-pin check connector located on left inner fender panel. Set dwell meter on 4-cylinder scale and observe needle movement with engine at idle. If needle fluctuates in proper range (mixture solenoid duty cycle is correct), no other action is necessary.
2. If needle fluctuates out of normal range, raise engine speed to 2000-3000 RPM for 2-3 minutes. Return engine to idle and set idle speed. If needle still fluctuates outside range, check spark plugs and ignition timing.
3. If spark plugs and ignition timing are okay, check vacuum hose routing, air cleaner element and carburetor. Adjust idle mixture screw until mixture solenoid duty ratio (at idle) is correct. See «3-CYLINDER MIXTURE SOLENOID DUTY RATIO»(/subaru/legacy/bcbjbf-1989-1994/remont/adjustments/#engine-controls-adjustments) table.

3-CYLINDER MIXTURE SOLENOID DUTY RATIO (1)

Note. If correct duty ratio cannot be obtained, see CARBURETOR in N - REMOVE/INSTALL/OHAUL article in the ENGINE PERFORMANCE Section.

Loyale (PFI) & XT

1. Ensure vacuum hoses, blow-by hoses, rocker arm cover, oil cap and other components connected to intake system are securely attached. Warm engine and oxygen sensor by operating engine at 2500 RPM for one minute after engine reaches normal operating temperature.
2. Plug canister purge hose after disconnecting it from intake manifold. Ensure auxiliary air valve is completely closed. Place transaxle in Neutral (M/T) or Park (A/T) position. To adjust idle speed, rotate idle adjusting screw on throttle body, at base of air induction hose. (Scheme 6) See «IDLE SPEED & CO LEVEL (LOYALE & XT)»(/subaru/legacy/bcbjbf-1989-1994/remont/adjustments/#engine-controls-adjustments) table.

Loyale (TBI)

1. Warm engine to normal operating temperature. Turn engine off. Disconnect electrical connector for air control valve. Start engine.
2. Turn idle adjustment screw and adjust idle speed to 500-600 RPM. (Scheme 5) Reconnect electrical connector for air control valve. Ensure idle speed is within specification. See «IDLE SPEED & CO LEVEL (LOYALE & XT)»(/subaru/legacy/bcbjbf-1989-1994/remont/adjustments/#engine-controls-adjustments) table.

IDLE SPEED & CO LEVEL (LOYALE & XT)

Scheme 5

Scheme 6

1. Ensure air filter is clean, vacuum hoses are properly routed, and timing is correct. Warm engine to operating temperature and attach inductive pick-up tachometer to No. 1 spark plug wire. NOTE: Because spark plugs No. 1 and No. 2 fire simultaneously, some tachometers may register twice the actual engine speed.
2. Check idle speed with all accessories off, then check with all accessories on. If idle speed is not specified in «IDLE SPEED SPECIFICATIONS (LEGACY)»(/subaru/legacy/bcbjbf-1989-1994/remont/adjustments/#engine-controls-adjustments) table, check self-diagnostic system for trouble code(s) and repair as necessary. See G - TESTS W/ CODES article in the ENGINE PERFORMANCE Section.

IDLE SPEED SPECIFICATIONS (LEGACY)

6-CYLINDER IDLE SPEED ADJUSTMENT

Idle speed is electronically controlled; adjustment is not necessary.

6-CYLINDER IDLE SPEED SPECIFICATIONS

Justy (PFI)

1. With ignition off, disconnect Throttle Position Switch (TPS) connector. Using an ohmmeter, measure resistance between terminals No. 2 and 3 with throttle fully closed, then measure with throttle fully open. (Scheme 7) Record reading.
2. Ensure readings are as specified. See «3-CYLINDER THROTTLE POSITION SWITCH RESISTANCE (PFI)»(/subaru/legacy/bcbjbf-1989-1994/remont/adjustments/#engine-controls-adjustments) table. If necessary, loosen attaching screws and rotate TPS until correct resistance is obtained. Replace TPS if resistance cannot be adjusted to specification.

3-CYLINDER THROTTLE POSITION SWITCH RESISTANCE (PFI)

Scheme 7

4-CYLINDER THROTTLE POSITION SENSOR

Note. All testing procedures are performed with engine at normal operating temperature.

1. With engine off, disconnect TPS connector. Using an ohmmeter, measure resistance between terminals No. 2 and 3. (Scheme 8) Record reading. Measure resistance between terminals No. 2 and 4 with throttle fully closed, then measure with throttle fully open. Record readings. Ensure readings are as specified. See «4-CYLINDER THROTTLE POSITION SENSOR RESISTANCE»(/subaru/legacy/bcbjbf-1989-1994/remont/adjustments/#engine-controls-adjustments) table.
2. If adjustment is necessary, loosen attaching screws. Check continuity by inserting a.028" (0.7 mm) feeler gauge between throttle lever and stopper screw. Continuity should exist. Continuity should not exist when gauge thickness is changed to.035" (0.9 mm). Rotate TPS until correct resistance is obtained. Tighten attaching screws. Replace TPS if resistance cannot be adjusted to specification.

Scheme 8

Loyale (PFI)

1. With engine off, disconnect TPS connector. Using an ohmmeter, measure resistance between terminals No. 1 and 3. (Scheme 9) Record reading. Measure resistance between terminals No. 1 and 2 with throttle fully closed, then measure with throttle fully open. Record readings.
2. Ensure readings are as specified. See «4-CYLINDER THROTTLE POSITION SENSOR RESISTANCE»(/subaru/legacy/bcbjbf-1989-1994/remont/adjustments/#engine-controls-adjustments) table. If necessary, loosen attaching screws and rotate TPS until correct resistance is obtained. Replace TPS if resistance cannot be adjusted to specification.

1. With ignition off, disconnect TPS connector. Using an ohmmeter, measure resistance between terminals "B" and "D". (Scheme 9) Record reading. Measure resistance between terminals "B" and "C" with throttle fully closed, then measure with throttle fully open. Record readings.
2. Ensure readings are as specified. See «4-CYLINDER THROTTLE POSITION SENSOR RESISTANCE»(/subaru/legacy/bcbjbf-1989-1994/remont/adjustments/#engine-controls-adjustments) table. If necessary, loosen attaching screws and rotate TPS until correct resistance is obtained. Replace TPS if resistance cannot be adjusted to specification.

Scheme 9

4-CYLINDER THROTTLE POSITION SENSOR RESISTANCE

XT

1. Disconnect connector from Throttle Position Sensor (TPS). Ensure throttle valve is fully closed. Using ohmmeter, check continuity between Black wire and Blue/White wire at TPS terminals. Continuity should exist.
2. Insert a .021" (.55 mm) feeler gauge between stopper screw of throttle chamber and stopper. Ensure continuity exists between Black wire and Blue/White wire at TPS terminals.
3. Ensure continuity is NOT present when thickness of gauge is changed to .036" (.92 mm). To adjust, loosen screws securing TPS until continuity is as specified. Replace TPS if proper adjustment cannot be made.

6-CYLINDER THROTTLE POSITION SENSOR

Note. All testing procedures are performed with engine at normal operating temperature.

1. Disconnect TPS electrical connector. Insert a .014" (.35 mm) feeler gauge between throttle lever and throttle screw. Connect an ohmmeter between Black wire and Gray wire at TPS terminals. Maximum resistance should be 5000 ohms. Remove feeler gauge.
2. Insert a .030" (.75 mm) feeler gauge between throttle lever and throttle screw. Ohmmeter should indicate infinity. Remove feeler gauge. Connect ohmmeter between Black/White wire and Black wire. Ohmmeter should indicate 3000-7000 ohms.
3. Connect ohmmeter between Green/Black wire and Black wire. With throttle valve closed, ohmmeter should read 4200-15,000 ohms. Open throttle valve to wide open throttle position. Ohmmeter should indicate 100-11,000 ohms.
4. Close throttle valve. With ohmmeter connected to Green/Black wire and Black wire, slowly open throttle. Ohmmeter reading should change smoothly as throttle goes from idle to wide open position.

See also:
• 3-CYLINDER VALVE CLEARANCE SPECIFICATIONS