Engine Controls - Adjustments - Carbureted Isuzu Amigo I

ENGINE MECHANICAL

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

Valve Clearance

1. Valves should be adjusted every 15,000 miles with engine cold. Remove valve cover. Position No. 1 piston on TDC of compression stroke and adjust valves listed in table. Refer to the «VALVE ADJUSTMENT SEQUENCE»(/isuzu/amigo/i-1989-1994/remont/adjustments/#engine-controls-adjustments-carbureted) table. VALVE ADJUSTMENT SEQUENCE Piston On TDC Adjust Intake No. Adjust Exhaust No. 1 1 & 2 1 & 3 4 3 & 4 2 & 4
2. Turn crankshaft one full turn (No. 4 piston on TDC of compression stroke) to adjust remaining valves. Measure valve clearance between rocker arm and valve stem. See VALVE CLEARANCE ADJUSTMENT table.

VALVE CLEARANCE ADJUSTMENT

IGNITION TIMING

1. Check ignition timing with engine at normal operating temperature. Set parking brake. Place transmission in Park (A/T) or Neutral (M/T). Connect tachometer. Connect timing light to No. 1 spark plug wire. Turn off all accessories and A/C (if equipped).
2. Disconnect and plug distributor vacuum advance hose. Disconnect and plug fuel vapor canister purge and EGR vacuum hoses. Start engine. Check ignition timing at specified RPM. See IGNITION TIMING specifications table.
3. If timing is out of adjustment, loosen distributor hold-down bolt and turn distributor in either direction until timing is within specification. After adjustment, retighten distributor hold-down bolt.

IGNITION TIMING (Degrees BTDC @ RPM)

Cold (Fast) Idle

1. Set parking brake. Remove air cleaner, leaving vacuum hoses connected. With engine off, slowly open throttle while pushing choke valve closed. Align fast idle adjusting screw with fast idle cam first step.
2. Connect tachometer. Start engine without touching accelerator or throttle lever. Check fast idle speed. See COLD (FAST) IDLE RPM table. If fast idle is not within specification, carburetor must be removed for adjustment. Refer to TO CARBURETOR in the appropriate N - REMOVE/INSTALL/OHAUL article in this s Section.
3. Ensure choke valve is in fully closed position. Align fast idle adjusting screw with fast idle cam first step. Measure clearance between primary throttle valve and throttle valve chamber wall. (Scheme 1)
4. Clearance should be.048-.058" (1.23-1.48 mm). Primary throttle valve should be at 25 degrees. If measured clearance is not within specified range, adjust clearance by turning fast idle adjusting screw.

COLD (FAST) IDLE RPM

Scheme 1

Idle Speed

1. Check idle speed with engine at normal operating temperature and air cleaner installed. Set parking brake. Connect tachometer. Place transmission in Park (A/T) or Neutral (M/T).
2. Turn off all accessories. DO NOT remove air cleaner. Ensure choke is fully open. Disconnect and plug distributor vacuum advance hose, fuel vapor canister purge hose and EGR vacuum hose.
3. Pinch off the hot idle compensator valve vacuum hose. (Scheme 2) Check engine idle RPM. See «IDLE SPEED SPECIFICATIONS»(/isuzu/amigo/i-1989-1994/remont/adjustments/#engine-controls-adjustments-carbureted) table. If idle RPM is out of adjustment, adjust by turning idle speed adjusting screw in either direction. (Scheme 3)

Scheme 2

Scheme 3

IDLE SPEED SPECIFICATIONS

Scheme 4

Scheme 5

1. Remove carburetor to drill out idle mixture screw plug (if necessary). Cover carburetor intake to prevent metal chips from entering. Mark center of mixture screw plug with a punch. Drill hole in plug and then thread a screw into hole. (Scheme 4) Pull on screw to remove plug. Remove metal chips surrounding idle mixture screw.
2. Lightly seat idle mixture screw. DO NOT overtighten. Back off adjusting screw 1 1/2 turns. Reinstall carburetor (if removed). Check idle speed with engine at normal operating temperature, choke open and air cleaner installed. Set parking brake. Place transmission in Park (A/T) or Neutral (M/T).
3. Turn off all accessories. If vehicle is equipped with power steering, ensure front wheels face straight ahead. Disconnect and plug distributor vacuum hose from carburetor, fuel vapor canister purge hose and EGR vacuum hose. Pinch off hot idle compensator vacuum hose. (Scheme 2)
4. Check idle speed and adjust idle speed screw if RPM is not within specification. See «IDLE SPEED SPECIFICATIONS»(/isuzu/amigo/i-1989-1994/remont/adjustments/#engine-controls-adjustments-carbureted) table. (Scheme 3) Using a dwell meter, connect positive lead to duty monitor connector and negative lead to ground. Duty monitor connector is located on right fender panel, near relay box. (Scheme 5)
5. Set dwell meter to 4-cylinder scale. Use idle mixture screw to set dwell to 36 degrees. After adjustment, reconnect idle set connector. Recheck idle speed and adjust if necessary. Stop engine and insert new idle mixture screw plug.

See also:
• VALVE ADJUSTMENT SEQUENCE