Engine Controls - Adjustments - Efi Isuzu Amigo I

ENGINE MECHANICAL

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

2.6L 4-Cylinder

1. Valves should be adjusted every 15,000 miles. With engine cold, remove rocker cover. Check torque of rocker arm shaft bracket nuts. Tighten rocker arm shaft bracket nuts to 16 ft. lbs. (22. N.m) on all models except Rodeo.
2. On Rodeo, adjust bracket nuts No. 1-8 to 16 ft. lbs. (22. N.m) and No. 9-10 to 6 ft. lbs. (8. N.m). Position No. 1 piston at TDC of compression stroke. Check valve clearance between the rocker arm and the valve stem. Refer to the «VALVE ADJUSTMENT SEQUENCE (2.6L)»(/isuzu/amigo/i-1989-1994/remont/adjustments/#engine-controls-adjustments-efi) and «VALVE CLEARANCE ADJUSTMENT (2.6L)»(/isuzu/amigo/i-1989-1994/remont/adjustments/#engine-controls-adjustments-efi) tables. VALVE ADJUSTMENT SEQUENCE (2.6L) Piston @ TDC Adjust Intake Valves: Adjust Exhaust Valves: 1 1 & 2 1 & 3 4 3 & 4 2 & 4
3. To adjust remaining valves, turn crankshaft 360 degrees (one full turn) until No. 4 piston is at TDC of compression stroke. Check valve clearance. See «VALVE CLEARANCE ADJUSTMENT (2.6L)»(/isuzu/amigo/i-1989-1994/remont/adjustments/#engine-controls-adjustments-efi) table. Replace rocker cover gasket (if necessary) and reinstall rocker cover.

VALVE CLEARANCE ADJUSTMENT (2.6L)

Trooper (2.8L), Pickup (3.1L) & Rodeo (3.1L)

Note. 2.8L and 3.1L engines are equipped with adjustable hydraulic lifters. Follow adjustment procedures carefully.

1. Remove rocker covers. Position No. 1 cylinder at TDC of compression stroke, aligning vibration damper reference mark with "O" mark on timing cover tab.
2. Check valve adjustment on intake valves of cylinders No. 1, 5 and 6, and exhaust valves on cylinders No. 1, 2 and 3. To adjust each valve, back off adjusting nut until lash (free play) can be felt at push rod by rotating push rod between fingers.
3. Tighten adjusting nut to zero lash. Zero lash can be determined by rotating push rod and simultaneously tightening adjusting nut. Zero lash is when push rod stops rotating. Tighten adjusting nut an additional 1 1/2 turns from zero lash.
4. Rotate crankshaft one revolution (360 degrees) and realign timing marks. No. 4 cylinder is now at TDC position. Adjust intake valves on cylinders No. 2, 3 and 4, and exhaust valves on cylinders No. 4, 5 and 6. Replace rocker cover gaskets (if necessary) and reinstall rocker covers.

VALVE CLEARANCE ADJUSTMENT (2.8L & 3.1L)

1. With transmission in Neutral or Park, start engine and warm to normal operating temperature. Turn engine and all accessories off. Connect tachometer. Connect timing light to No. 1 spark plug wire.
2. Disconnect and plug fuel vapor canister purge hose and EGR vacuum hose. Start engine and ensure idle is 900 RPM. Adjust idle as required. Check ignition timing. See «IGNITION TIMING»(/isuzu/amigo/i-1989-1994/remont/adjustments/#engine-controls-adjustments-efi) specification table.
3. If adjustment is required, loosen distributor hold-down bolt and turn distributor until timing is within specification. Tighten distributor hold-down bolt and recheck timing. Adjust idle speed as required.

Trooper (2.8L); Pickup & Rodeo (3.1L)

1. With transmission in Neutral or Park, start engine and warm to normal operating temperature. Ensure CHECK ENGINE light is off. Turn engine and all accessories off.
2. Disconnect distributor set timing connector to put Electronic Spark Timing (EST) in by-pass mode. The White set timing connector has 2 Black/White wires and is located under center console tray between front seats on Trooper (inside left side cover near driver's left foot on Rodeo and Pickup). DO NOT disconnect 4-wire connector at distributor.
3. Connect timing light to No. 1 spark plug wire. Start engine. Set ignition timing to specification. See «IGNITION TIMING»(/isuzu/amigo/i-1989-1994/remont/adjustments/#engine-controls-adjustments-efi) specification table. Reconnect timing connector.
4. Clear ECM trouble codes by removing ECM fuse or disconnecting battery for 30 seconds. Trouble codes can also be cleared by disconnecting vehicle battery. However, other memory functions (clock, radio, etc.), will need to be reset.

IGNITION TIMING (Degrees BTDC@RPM)

1. Check idle speed with engine at normal operating temperature and throttle fully closed. Turn off all accessories.
2. Ensure transmission is in Neutral or Park. Disconnect fuel pressure regulator vacuum switching valve harness connector, located on right fender panel, at rear of battery. Disconnect and plug fuel vapor canister purge and EGR vacuum hoses.
3. Start engine and ensure idle speed is within specification. See «IDLE SPEED SPECIFICATIONS»(/isuzu/amigo/i-1989-1994/remont/adjustments/#engine-controls-adjustments-efi) table. If idle speed is not within specification, adjust idle speed adjusting screw on throttle body. (Scheme 6)

Scheme 6

Note. On 2.8L and 3.1L engines, curb idle speed is computer controlled and cannot be adjusted. Minimum idle speed is adjustable, but should only be adjusted when installing a new Idle Air Control (IAC) valve or when replacing throttle body assembly. Original equipment throttle bodies are pre-adjusted and sealed at the factory.

Scheme 7

Scheme 8

1. Check minimum idle speed with engine at normal operating temperature, and transmission in Neutral or Park. Turn engine and all accessories off. Connect tachometer to engine.
2. With engine off, install jumper wire between ALDL diagnostic connector terminals "A" and "B". ALDL is located under center console tray and sometimes covered with a plastic cover. (Scheme 7)
3. Turn ignition to ON position, but DO NOT start engine. Wait at least 45 seconds and disconnect Idle Air Control (IAC) valve connector at throttle body. Disconnect timing set connector to put Electronic Spark Timing (EST) in by-pass mode.
4. The White timing set connector has 2 Black/White wires and is located under center console tray between front seats on Trooper (inside left side cover near driver's left foot on Pickup and Rodeo). DO NOT disconnect 4-wire connector at distributor.
5. Start engine and allow system to go into closed loop operation. Check minimum idle speed. Minimum idle speed should be 650-750 RPM. If adjustment is required, go to next step. If adjustment is not required, go to step 7).
6. Minimum idle stop screw is factory sealed. Use an awl to pierce aluminum idle stop screw plug and pry it out. (Scheme 8) Adjust minimum idle speed to specification.
7. Whenever minimum idle speed is adjusted, throttle position changes. Adjust throttle position sensor. See «THROTTLE POSITION SENSOR (TPS) OR THROTTLE VALVE SWITCH (TVS)»(/isuzu/amigo/i-1989-1994/remont/adjustments/#engine-controls-adjustments-efi). With engine off, reconnect timing set connector and remove jumper wire from ALDL diagnostic connector. Reconnect IAC valve connector.

IDLE SPEED SPECIFICATIONS

TROOPER 2.6L (A/T)

Note. Trooper 2.6L A/T models use both a throttle position sensor and throttle valve switch. For information on throttle valve switch, see AMIGO, PICKUP, RODEO & TROOPER 2.6L (M/T).

Throttle Position Sensor (TPS)

1. Turn ignition to ON position. DO NOT start engine. Using Scan tester or equivalent, adjust throttle position sensor (TPS) to 0.42-0.54 volt at idle position. Leaving TPS connector assembled, slide 3-wire water shield off TPS side of connector.
2. Using a voltmeter, backprobe TPS connector. Connect positive voltmeter lead to Red wire and negative lead to Black wire. With throttle lever at idle position, voltmeter reading should read 5 volts on Red wire. If reading is 5 volts, go to next step. If reading is not 5 volts, repair TPS circuit. See appropriate G - TESTS W/ CODES article in the ENGINE PERFORMANCE Section.
3. Backprobing TPS connector, measure voltage at White wire. If voltage is greater than 4 volts, go to next step. If voltage is less than 4 volts, replace TPS.
4. Open throttle lever to Wide Open Throttle (WOT) position. Voltage on White wire should be less than 2 volts. If difference between idle voltage reading and WOT voltage reading is not 3-4 volts, adjust TPS. If TPS will not adjust to specification, replace TPS.

AMIGO, PICKUP, RODEO & TROOPER 2.6L (M/T)

Note. Trooper 2.6L M/T models use only a throttle valve switch. The following information, however, on the throttle valve switch also applies to Trooper 2.6L A/T models, which use both a throttle position sensor and throttle valve switch

Scheme 9

Scheme 10

1. Warm engine to normal operating temperature. Move throttle lever away from throttle stop screw. (Scheme 9) Place a.24" (.60 mm) feeler gauge on top of stop screw. Allow throttle linkage to close on feeler gauge.
2. Disconnect TVS connector. Using an ohmmeter, connect positive lead to TVS terminal "I" and negative lead to TVS terminal "P". (Scheme 10) Ohmmeter should indicate continuity (closed circuit).
3. If ohmmeter does not indicate continuity, loosen TVS adjusting screws. Rotate switch until continuity is attained and tighten adjusting screws. Remove feeler gauge. Reconnect TVS connector.

TPS can be adjusted using a Scan tester or the following procedure

1. Turn ignition off. Disconnect TPS connector. Install 3 jumper wires between TPS and TPS harness connector. Turn ignition to ON position. DO NOT start engine.
2. Using a voltmeter, backprobe TPS connector. Connect negative voltmeter lead to terminal "A" (Black wire) and positive voltmeter lead to terminal "B" (Blue/Red wire). (Scheme 11)

Scheme 11

1. With throttle closed, Scan tester or voltmeter should read 0.42-0.54 volt. If TPS voltage is not within specification, loosen TPS attaching screws and adjust TPS until voltage is within specification.
2. Tighten TPS attaching screws and recheck voltage. If voltage is okay, turn ignition off and reconnect TPS connector.

See also:
• VALVE ADJUSTMENT SEQUENCE (2.6L)